Question: I think the bearings in my engine are worn out or damaged? Are they worth replacing?

Answer: Yes and No. Sounds like we are waffling around on this one doesn't it? Well it comes down to HOW you replace them.

Consider this:

1) KNOWLEDGE and TOOLS. To actually replace the bearings in your existing crankcase you have to take them out. We recommend replacing front and rear bearings at the same time because it would be unusual to find one worn out and the other in good shape. To get them out you have to know what you are doing and most importantly to put new bearings in you have to be careful not to damage them during installation. Removing and installing bearings requires some knowledge and a few small special tools to do the job right. In our experience most modelers have some difficulty with this and often damage the new bearings.

2) WORK/EFFORT/TIME. Do you have the time? It takes about 30-60 minutes to do a good job IF you have the tools and knowledge to change bearings effectively.

3) COSTS. The cost of two bearings can vary widely from engine to engine and source to source. The price for a front/rear set of bearings for the VMAX 46PRO and 52PRO is about $20 as of 20050228. This may have increased since then. You may be able to run around town and find them cheaper at a bearing house if you can get the size you need but with gas and automobile depreciation the way it is today you can't drive far even to get bearings for free!

Question: So what to do when you have neither the knowledge, the tools, the time or money to burn? Is there another way short of dumping the engine?

Answer: Yes there is! Swap out the crankcase complete with bearings. Once you've got the engine taken apart to the point where you can actually remove the bearings you are way ahead of the game if you just replace the entire crankcase and bearing set with brand new components. As of 20050228, the price for the crankcase with bearings already installed for the VMAX 46PRO and 52PRO was just $5 more than  the cost of the bearings by themselves. So for a few bucks more you can do less work, have a much better chance of a satisfactory outcome and get the job done quickly so you can get back to flying!

Conclusion: On a VMAX engine we recommend changing the crankcase and bearings for a few dollars more than just changing the bearings themselves.

Question: I think the piston and sleeve in my engine is worn out or damaged. Are they worth replacing?

Answer: Well it comes down to cost and HOW you replace them.

Consider this:

1) KNOWLEDGE and TOOLS. To actually replace the piston and sleeve you have to disassemble your engine in order to take them out. We recommend replacing the piston and sleeve together in any ABC engine and in many cases it is prudent to so in a ringed engine as well. The conrod and wrist pin and wrist pin retainer should also be replaced at the same time. To get these parts out of your crankcase you have to know what you are doing and most importantly to put the new components in you have to be careful not to damage them during installation and you must align the ports correctly. Removing and installing pistons and sleeves requires some knowledge and a few small special tools to do the job right. In our experience most modelers have some difficulty with this and may damage the sleeve and/or conrod bottom end.

2) WORK/EFFORT/TIME. Do you have the time? It takes about 30-60 minutes to do a good job IF you have the tools and knowledge to change these components effectively.

3) COSTS. The cost of a piston, sleeve, conrod, wrist pin and retainer can vary widely from engine to engine and source to source. They are the most precise parts in the engine and in no case are they cheap. The price for a piston, sleeve, conrod and wrist pin set for the VMAX 46PRO and 52PRO is about $40 as of 20050228. This may have increased since then.

Question: So what to do when you have neither the knowledge, the tools, the time or money to burn? Is there another way short of dumping the engine?

Answer: Yes there is! If your carburetor and muffler are working well... ask us for a "short block". A short block is the entire engine ready to go except for carburetor, carburetor cinch bolt,  muffler, muffler screws, prop nut and washer.  Just remove your prop nut, washer, carb, muffler and retaining bolts for both, re-install them on the short block and you are ready to go with just about an entirely brand new engine! As of 20050228, the price for a short block for the VMAX 46PRO and 52PRO was just $5-10 more than  the cost of the piston, sleeve, conrod, wrist pin and retainer set. So for a few bucks more you can do less work, have a much better chance of a satisfactory outcome and get the job done quickly so you can get back to flying!

Conclusion: On a VMAX engine we recommend going with a short block replacement rather than changing the piston and sleeve. It will cost just a few dollars more than the parts but has an almost 100% chance of producing a satisfactory outcome with much much less work.

Question: What is After Run Oil and Why Use It?

Answer: After Run Oil helps to prevent rust from forming in your engine. Rust is a major cause of engine and bearing failure.

Better Answer: Section 7 of the Owners Manual for VMAX Engines outlines the correct procedure for Care and Maintenance of Your Engine and the use of After Run oil. If you have misplaced the Owners Manual it can be downloaded from our support section at www.richmondrc.com/vma/supportdir.htm

Please review the following information about Rust:

Question: Why is Rust a problem in Glow Engines: How can it be prevented?

Answer: Rust reduces the power and life of your engine. To inhibit the formation of rust remove all methanol from your engine and use After Run Oil after each day of flying.

Better Answer: Glow fuel consists primarily of methanol, lubricant and nitromethane. Methanol attracts water vapour. This water vapour condenses into water  inside your engine which in turn will cause rust to form on the steel parts of your engine such as the crankshaft and bearings.

Rust does two things, it erodes and pits the smooth surfaces of the crankshaft and bearings and it flakes off as a gritty abrasive when the engine is operated next. The erosion of the surfaces reduces RPM and increases heat and load on the surfaces. The loose rust that flakes off as a gritty abrasive induces wear on all the moving parts including the piston and sleeve. The end result is that RUST reduces performance (RPM and power) and reduces the life of the engine and leads to premature component failure. Bearings are particularly susceptible to failure caused by Rust. Crankshaft front bearing leakage and in particular crankshaft to conrod pin failure are also common problems caused by rust.

There are two simple things you can do to inhibit the formation of rust in your engine:

1) Avoid leaving methanol in your engine.

When you stop using your VMAX engine for the day, run the engine dry by pinching the fuel line feeding the carburetor and let the engine run out of fuel. This will burn up most of the methanol in your engine.

2) Use After Run Oil in your engine after each day of use.

Remove the glow plug and carefully put 6-10 drops of Afterrun Oil (Pacer After Run recommended) into the combustion chamber and another 6-10 drops into the carburetor inlet. Turn the engine over by hand 10 times. Reinstall the glow plug, close the carb and insert a small plug of wadded paper towel into the carburetor intake.

If you are not planning on using your engine for a while please see following information about storage of your engine:

Question: The spray bar in my carburetor appears to rotate when I rotate the throttle barrel or needle valve. Does this matter? I also notice that the spray bar has a groove with some holes in the groove. The groove itself appears to line up with the bottom of the fuel inlet nipple. Do the holes in the groove have to line up with the bottom of the fuel inlet nipple or anything else?

Answer: Rotation of the Spray bar is fine. The holes in the groove do not need to line up with anything. Fuel flows from your tank into the fuel inlet nipple, down the nipple into the carb where it flows into the groove and from there the fuel flows through the holes in the groove and into the spray bar inlet. The groove and two holes in the groove ensures that fuel can flow into the spray bar inlet regardless of orientation of the holes relative to the fuel nipple and allows the throttle barrel to rotate and thereby expanding or restricting the volume of air into the engine.

The needle valve controls the amount of fuel that flows from the exit end of the spray bar into the carburetor throat. It is the mixing ratio of fuel to air that determines how lean or rich the engine runs. When the needle valve is turned in (clockwise) the needle restricts the fuel flowing out of the end of the spray bar and the engine runs lean (less fuel relative to the volume of air). When the needle valve is turned out more (counterclockwise) the fuel flows more plentifully and the engine runs richer (more fuel relative to the volume of air).

Question: The carburetor rotor (barrel with a large hole in it, visible by looking down into the throat of the carburetor) is difficult to rotate and feels rough when I do get it to move. What is causing this and is there anything that I can do about this?

Answer: In the vast majority of cases this is caused by a bit of dirt or debris having worked it's way into the carburetor and lodging between the rotor and the carburetor body OR the idle stop screw and a piece of grit acting to bind the rotor. The solution is in flushing away the grit so nothing can act to bind the rotor from rotating OR the idle stop screw not seating properly in the rotor slot.

Procedure:

1) Please consult your owners manual Pages 6 and 7. You must be able to consult the owners manual to carry out this procedure. If you have misplaced your owners manual, you may download a copy of the manual from www.richmondrc.com/support.htm > VMAX Information.

2) Review the engine 3-View illustration on Page 6. Remove the carburetor from your engine by loosening the nut on the end of 2090 and gently rotating the carburetor to and from while pulling  the carburetor gently upwards and out of the engine.

3) Review the exploded carburetor 3-View illustration at the bottom of Page 6. Carefully remove 3080 (Idle stop screw) and then remove the entire assembly consisting of 3060, 3050, 3040. Then remove 3030 (spring). Flush the carburetor with clean fuel several times ensuring that you flush down through the hole vacated by 3080 and flush the area vacated by 3040. Lubricate the hole for 3080 and lubricate the area vacated by 3040 with After Run Oil.

4) Reassemble the carburetor carefully. First install 3030 (spring) noting that the wider end of the spring goes into the carburetor first. Then install the entire assembly consisting of 3060, 3050, 3040. Rotate this assembly so that the slot in 3040 aligns with the hole for 3080. Install 3080 (Idle stop screw) and tighten it so that it is snug on the washer. Do NOT overtighten 3080... this is not a farm tractor... it's a precision fitted model airplane engine. Snug is good enough... leave your pipe wrench in the garage! If you find that the head and washer of 3080 will not seat against the carburetor body, back off 3080 and realign 3040 slightly and try again. 3080 must engage in the slot of 3040.

5) You should now be able to rotate the carburetor rotor freely. If you find that the carburetor will not rotate or remains tight and rough, you will need a new carburetor assembly #463000.

Question: How do I set the low speed mixture of my carburetor?

Answer: Generally you should not adjust the factory settings until the engine has been run for 4-6 tanks of fuel at least AND you should only adjust the factory settings if the engine does not idle well or does not transition to higher RPR well.

All engines idle poorly and transition poorly on the first tank of fuel, a bit better on the 2nd, 3rd and 4th tanks and progress to normal operational reliability by about the 6th tank of fuel.

If you find that after this breakin period, your engine dies at idle or dies when trying to increase the RPM from idle, you may need to adjust the idle mixture. Before attempting to adjust the idle mixture, make sure that the problem is not with your glow plug, fuel tank or tubing etc. Then gently turn the idle screw all the way in (clockwise) while counting how many turns or fractions of turns the factory setting is from fully closed. This turn count will enable you to go back to the factory setting at any time. Do so now... turn the idle screw back out (counter clockwise) to the factory setting.

The low speed mixture screw works the same way as the main needle valve... turning it IN (clockwise rotation) makes the engine run leaner (less fuel,  lower ratio of fuel to air) and turning it OUT (counter clockwise rotation) makes the engine run richer (more fuel, higher ratio of fuel to air).

To make adjustments to the low speed mixture, we recommend the following procedure. Review the instruction manual first. All of it! Then read it again for good measure.

Now put your engine on an engine test stand and set the center line of the test stand fuel tank about 1/4" below the needle valve. Check your tubing for leaks and secure attachment. Fill the tank with good quality fuel as described in the instruction manual. 10% nitro maximum. 18% oil minimum with Oil being a mix of synthetic and castor.

Start the engine, reduce the speed to idle. Let it idle (even if rough running) for about 30 seconds. Then suddenly open the throttle fully for maxium RPM and listen carefully to your engine. If your engine gurgles and sputters as you open the throttle with lots of grayish smoke and oil coming out of the muffler, then your idle mixture is too rich. Lean out the setting by turning the mixture adjustment screen IN (clockwish) by 1/8 to 1/4 of a turn. Then try again and see if the engine transitions to high RPM any better. If it is better you are going in the right direction. If it is worse (even more oil and smoke). If at some point your engine goes from idle directly to a high RPM and then dies without notice thereafter, your low speed mixture is too lean... back the idle mixture screw out (counter clockwise) about 1/8 of a turn and try again. The ideal settting is one where the engine does not sputter and gurgle when trying to rev up but also does not stall after reving up!

Once you have this working well on an engine test stand, move the engine to your model and check out the low speed mixture again. You may need a further slight adjustment depending on the height of the models fuel tank relative to the needle valve.

Question: My engine will not shut off. What do I do?

Answer: Generally you should not adjust the factory settings until the engine has been run for 4-6 tanks of fuel at least AND you should only adjust the factory settings if the engine does not idle well or does not transition to higher RPM well.

All engines idle poorly and transition poorly on the first tank of fuel, a bit better on the 2nd, 3rd and 4th tanks and progress to normal operational reliability by about the 6th tank of fuel.

If you find that after this breakin period, your engine will not shut off  review the documentation first. All of it! Then read it again for good measure.

Now put your engine on an engine test stand and set the center line of the test stand fuel tank about 1/4" below the needle valve. Check your tubing for leaks and secure attachment. Fill the tank with good quality fuel as described in the instruction manual. 10% nitro maximum. 18% oil minimum with Oil being a mix of synthetic and castor.

Do not start your engine yet.

Look into the carburetor throat and ensure that the carb barrel can rotate fully so that there is no opening remaining. If you find a small opening remaining, adjust the idle stop screw (not the mixture... the stop screw) so that you can rotate the throttle to fully closed.

Loosen the carburetor cinch bar by backing off the retaining nut a turn or so. Gently wiggle the carburetor and pull it out of the engine. Inspect the O-ring around the flange of the carburetor to ensure that the O-ring is not damaged or nicked. Carefully reinsert the carburetor back into the engine and tighten the cinch bar nut securely while pressing the carburetor firmly into the engine. It is important to have a tight seal between the carburetor and the engine... the O-ring provides this seal provided it is firmly seated and is not damaged.

Now start your engine. Provided that the engine has at least 6 tanks of fuel through it and it is mounted on a test stand with the fuel tank set up properly, you should be able to close down the throttle barrel and the engine should stop in 5-10 seconds or sooner. If your engine continues to run for longer than that, the engine is drawing air from somewhere such as:  

1. From the fuel feed (air in the lines caused by a leak or foaming fuel due to vibration), or
2. Through a poor seal around the carburetor flange, or
3. Around a poor fitting carburetor barrel due to wear, or
4. Through the front bearing due to an alignment problem usually caused by the crankshaft being bent after a crash or drop.

To resolve which is which:

1. Check the fuel system again. Change the tank and the tubing. Cushion the tank on foam sheeting and ensure the fuel is not foaming.
2. Check the O-ring seal again.
3. Very very carefully, plug the inlet to the carburetor throat while the engine is idling.  If the engine stops the carb barrel is leaking. You will need a new carb barrel and body or more likely it would be best to install a new carburetor.  
4. Remove the prop and thrust washer. Cut a very thin sheet of gasket paper or laminated playing card material and insert it as a gasket around the crankshaft between the crankcase and the thrust washer. Reapply the thrust washer, prop, prop washer and prop nut. Tighten securely. The idea here is to create a temporary gasket across the face of the front bearing to restrict any suction induced air flow. Start the engine, idle down. If the engine will stop with the gasket in place, air is being sucked into the engine from the front of the engine when the gasket is not present. This will require a new crankshaft or possibly a new crankcase or both. It may be more cost effective to purchase a new short block. Professional service is recommended. 

Question: I have had a crash into dirt, sand, grass or other loose material and some of this debris is all over my engine and may have worked its way inside the engine. How to do I clean the debris off and out of my engine?

Answer: Wear eye protection and rubber gloves. Work outdoors. Invert the engine. Carefully rotate the throttle so that the carburetor barrel is closed. Plug the carb inlet with a wad of paper towel soaked in Oil. Clean away all of the debris from outside the engine using a tooth brush and Fantastic diluted 50/50 with water. Remove the muffler, the glow plug, the back plate, the prop nut, the prop washer, the thrust washer, and the carburetor. Flush the crankcase with Pacer Degreaser while holding the engine slightly nose high. Flush the cylinder via the Glow Plug hole while holding the engine with the exhaust outlet facing downwards. Flush the Front Bearing while holding the engine nose down. Flush the carburetor with Pacer Degreaser. Let the engine dry. Lubricate the crankcase and rear bearing with Pacer After Run Oil. Lubricate the crankshaft with Pacer After Run oil via the carburetor inlet in the crankcase. Lubricate the carb barrel with Pacer After Run Oil.

Turn the engine over several times by hand. Flush all parts again with Pacer Degreaser. Let dry and reapply After Run oil liberally to all internal components. Re-install the crankcase back plate and the carburetor. Reinstall the thrust washer, prop washer, prop nut and glow plug.

Question: Do you have 3 views that show dimensions of VMAX Engines?

Answer: Yes we do. They are included in the Owners (Instruction) Manuals. Check out the last few pages.

If you do not yet have your VMAX Engine or have misplaced the manuals, links to various manuals have been included here.

Please see the attached PDF documents related to this engine. File names indicate the nature of the document.

Question: How should I tighten the head bolts on my engine? How tight is tight enough? Can I over do it?

Answer: The head bolts should be snugly tightened by hand using the small allen wrench supplied. Work in stages back and forth across the head. Do not unevenly or overtighten the bolts or you will warp the crankcase, or the head or strip or break the bolts.

Better Answer: There is a strong bias amongst modelers to overtighten head bolts and engine bolts in general. As the Operators Manual points out your engine is a precisely made piece of machinery... you are not working on a tractor here... leave your hammer, vice grips and power tools in the drawer. All you need is the allen key provided and a delicate, firm touch.

Install the head gaskets and head on to the engine. Insert the head bolts loosely into their mounting holes and screw then down so that they are loosely retaining the head. Now work in a criss cross pattern and in phases. Do not tighten any one bolt all the way down. Tighten one bolt so that it in contact with the head, now tighten the bolt across from the first on the other side of the head. Now come back and move over to the next loose bolt... go back and forth and around the head like this until all head bolts are just tight enough to touch the top of the head. Now begin again, tighten say 1/2 a turn and then jump across the head and do the say thing... criss cross and move around the head until all bolts are at the same tightness. Now go in 1/4 turn increments back and forth and around the head until you the bolts feel snug but not squeekly tight when using the allen key attached. That's it you are done! Do not overtighten the bolts!

Question: My engine is mounted inverted and I find that it bogs down and sometimes stops below mid throttle. Can anything be done about this?

Question: What is wrong when an engine runs well on the ground or when I hold it firmly before flight but the engine bogs down or stops shortly after becoming airborne?

Answer: The best way to sort this out is to use a test stand. Set up the test stand fuel tank and fuel lines properly. Get the engine running and satisfy yourself that the engine runs well on the test stand.

Now put the engine back in the model. Start the engine and set the mixture with the model on the ground. With the engine at high RPM, pick the model up and holding it nose high, gently hold it between your finger tips. Emphasis on gently! Don't drop it but try to barely hold it. Be careful. The idea is let the model be lightly held nose high but be safe while you are at it. Wait about 30 seconds with the nose high and the model held loosely.

If the engine bogs down after a period of time when it is held lightly in a nose high attitude, the mixture is too lean. Try a richer mix (generally by rotating 1/8 of a turn out on the needle valve) and do the test again. Normally you will get to a point when the mixture is about right but if you find that you cannot get a reliable setting check the following:

- the glow plug (change to be sure)

- the fuel (10% max for VMAX engines) with at least 18% blended oil (castor & synthetic). Do NOT use more than 10%. Your engine has been designed to work best with up to10% nitro.

- the plumbing (tubes tight etc)

- muffler pressure (gasket in, bolts snug, tubing securely attached)

- the prop (back off a bit on pitch and/or diameter)

If you still encounter problems when held lightly in a nose high attitude, pay attention to your finger tips where they contact the model... is the airframe vibrating? Do you feel a bit of a tingle in the tips of your fingers?

Vibration is the hidden boogy man in some of these cases. Here is what happens... on the ground or when tightly held the model does not vibrate as much. When loosely held in a nose high attitude or in flight... high frequency vibration is able to make the fuel foam or ingest air bubbles. This leans the mixture and bogs the engine down (overheats). To reduce vibration you MUST MUST MUST balance the prop AND the spinner. Then make sure the fuel tank is mounted with the rubber gasket in place and the tank cradled by foam or the dowels on the power module. If you are using a non-wood prop and after balancing the problem persists, change to a balanced WOOD prop and try again. Remember non wood props flex and change pitch a bit with RPM and this induces some vibration. Wood props hold their pitch better and vibrate less once properly balanced.

In conclusion: If the engine runs on a test stand it is something about the model or engine prop/spinner that is the cause of your problems. If the engine runs in the model when level on the ground, you are likely going lean in the air. Examine for the causes of the engine going lean in the air... what is reducing fuel flow or increasing air flow into the carburetor? Remember that vibration is much more of a problem than many people realize... balance the prop AND the spinner. Try a balanced wood prop.  

Question: How much engine power is appropriate? Many models give a range of engine sizes... should I use an engine that is at the bottom of the range or go for broke and use the biggest engine recommended?

Answer: If in doubt go with something that is more or less in the middle of the range unless the distributor or your dealer have some specific recommendations.

DO NOT use an engine larger than the maximum size recommended by the model manufacturer. You run the risk of overstressing the airframe which can lead to sudden breakup of the model in the air and may injure someone.

Better Answer: Generally manufacturers specify a range of engine sizes for a model. An engine in the middle usually works well but you might want to consider going with the higher end of the range if you are going to be flying at altitudes above 2000 feet or in very hot weather or flying off of floats. Naturally if you are doing all of these, flying at high altitudes from a lake on a hot day... the bigger engine is the better choice. You might also want to ask around in your area to see what other RC flyers are doing. Be a bit cautious of the "power at all costs" type of recommendations but listen carefully when you get advice from those who have thought it through and tried it out.

Question: What size propeller should I use on my VMAX Engine?

Answer: Please see the documentation that came with your VMAX Engine. There is a propeller chart that will help you with choosing an appropriate propeller. This chart  is usually located towards the back of the manual, often it is on or near Page 8.

Please note that although prop size is related to the engine size, there are many other factors to consider. Altitude, temperature and aircraft type all are important factors that affect the prop selection. Air at higher altitudes and/or warmer temperatures is thinner and produces less thrust than lower altitude and/or colder air. Fuel type, nitro content and glow plug type can also play a role. A good idea is to talk to some of the flyers at your club. They will be familiar with the altitude and climate in your area and have a good idea of what props work best on what size engines.

We have included below, a manual from VMAX that has a propeller chart for use as a reference. This is a good guideline and works as a starting point for VMAX and most 2 stroke engines.  

Question: I need to change the cylinder on my VMAX ABC type engine. How do I remove the Cylinder without damaging anything?

Answer: Install a propeller and tighten it securely. Remove the glow plug and brass glow plug washer. Remove the head. Rotate the propeller until the piston is at the bottom of the large exhaust port. Position the brass glow plug washer on top of the piston so that about 10-15% of  the brass glow washer protrudes into the exhaust port but not beyond the outside diameter of the cylinder. Hold the engine level and rotate the prop so as to raise the piston. The brass glow plug washer will catch on the side of the exhaust port and you can then use the leverage of the propeller to literally lift the cylinder out of the crankcase.

Note that in nearly 100% of cases, when replacing the cylinder in an ABC engine, the piston should be replaced also. They are generally sold as a set.

Better Answer: The trick to this is NOT to use vice grips, pliers or other tools on the cylinder itself. Follow the procedure outlined in the Answer above. The brass washer is softer than the plated cylinder and the piston so that it will not mark either when used as a lifting wedge. The propeller provides plenty of convenient leverage to literally lift the cylinder right out of the crankcase.

If the cylinder will not move using this technique try the following: Install the engine in a test stand or clamp GENTLY in a vice (emphasis on GENTLY!). Keep uplifting pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. This will expand the crankcase somewhat allowing the cylinder to move more easily. Increase the pressure on the prop and the cylinder will move upwards and out of the crankcase.

If the cylinder will still not move after heating the crankcase try the following next: Leave the engine clamped down. Get a can of Pacer Degreaser. Use eye protection and rubber gloves. Move outside. We are not going to use the Degreaser as degreaser per se. It has another quality that we need. It has a very high evaporation rate and cools whatever it is sprayed on. So we are going to use it to cool the cylinder liner after heating the crankcase. The heat will expand the crankcase and the degreaser cooling will contract the cylinder allowing the cylinder to be removed from the crankcase. It is important to DO THIS OUTSIDE. Do NOT USE your heat gun and your degreaser at the same time. Keep uplifing pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. Don't go overboard. Just get it nice and warm. TURN OFF THE HEAT GUN and set it aside at a safe distance. Now take the degreaser and spray a good blast into the cylinder on top of the piston. This will cool the cylinder quickly. Now increase the pressure on the prop and the cooler contracted cylinder will move upwards and out of the heated expanded crankcase.

Question: I need to change the Crankshaft in my VMAX ABC type engine. How do I remove the Crankshaft without damaging anything?

Answer: First of all you need to remove the cylinder (sleeve) and then the piston. Please see the How to Remove the Cylinder (Sleeve) and the How to Remove the Piston procedures below.

Once the cylinder and piston have both been removed. With the crankcase backing plate off remove the thrust washer, propeller, prop washer and prop nut. Carefully thread the prop nut back on to the crankshaft so that one thread remains unengaged. The end of the crankshaft should be just inside the prop nut.

Turn the engine so that it is pointing with the prop nut up. Rest the back of the bottom of the crankcase on a solid surface. Using a hammer tap sharply on the prop nut driving the crankshaft down and into the engine. Remove the prop nut and withdraw the crankshaft back and out of the back of the crankcase.

Question: I need to change the cylinder on my VMAX ABC type engine. How do I remove the Cylinder without damaging anything?

Answer: Install a propeller and tighten it securely. Remove the glow plug and brass glow plug washer. Remove the head. Rotate the propeller until the piston is at the bottom of the large exhaust port. Position the brass glow plug washer on top of the piston so that about 10-15% of  the brass glow washer protrudes into the exhaust port but not beyond the outside diameter of the cylinder. Hold the engine level and rotate the prop so as to raise the piston. The brass glow plug washer will catch on the side of the exhaust port and you can then use the leverage of the propeller to literally lift the cylinder out of the crankcase.

Note that in nearly 100% of cases, when replacing the cylinder in an ABC engine, the piston should be replaced also. They are generally sold as a set.

Better Answer: The trick to this is NOT to use vice grips, pliers or other tools on the cylinder itself. Follow the procedure outlined in the Answer above. The brass washer is softer than the plated cylinder and the piston so that it will not mark either when used as a lifting wedge. The propeller provides plenty of convenient leverage to literally lift the cylinder right out of the crankcase.

If the cylinder will not move using this technique try the following: Install the engine in a test stand or clamp GENTLY in a vice (emphasis on GENTLY!). Keep uplifting pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. This will expand the crankcase somewhat allowing the cylinder to move more easily. Increase the pressure on the prop and the cylinder will move upwards and out of the crankcase.

If the cylinder will still not move after heating the crankcase try the following next: Leave the engine clamped down. Get a can of Pacer Degreaser. Use eye protection and rubber gloves. Move outside. We are not going to use the Degreaser as degreaser per se. It has another quality that we need. It has a very high evaporation rate and cools whatever it is sprayed on. So we are going to use it to cool the cylinder liner after heating the crankcase. The heat will expand the crankcase and the degreaser cooling will contract the cylinder allowing the cylinder to be removed from the crankcase. It is important to DO THIS OUTSIDE. Do NOT USE your heat gun and your degreaser at the same time. Keep uplifing pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. Don't go overboard. Just get it nice and warm. TURN OFF THE HEAT GUN and set it aside at a safe distance. Now take the degreaser and spray a good blast into the cylinder on top of the piston. This will cool the cylinder quickly. Now increase the pressure on the prop and the cooler contracted cylinder will move upwards and out of the heated expanded crankcase.

Question: I need to change the Piston in my VMAX ABC type engine. How do I remove the Piston without damaging anything?

Answer: First of all you need to remove the cylinder (sleeve). Please see the How to Remove the Cylinder (Sleeve) procedure below.

Note that in nearly 100% of cases, when replacing the piston in an ABC engine, the cylinder should be replaced also. They are generally sold as a set.

Once the cylinder has been removed you can remove the piston complete with connecting rod and wrist pin. There is a trick to this. Please put away your hammer, vice grips, pliers and cutting torch and obtain a carriage bolt that is about 3/16" in diameter and about 3" long. Carriage bolts have a rounded dome like head and are available in pretty much any hardware store.

Securely tighten the prop nut and prop which will serve to pull the crankshaft as far forward in the crankcase as possible. Remove the crankcase backing plate. Lubricate the bottom of the connecting rod where it attaches to the crankshaft pin. Use Pacer After Run Oil or other lubricant. Remembering that there is no cylinder in the crankcase, carefully and slowly rotate the engine 2-3 times by hand and stop with the piston at top dead center (highest point) in the crankcase.

Carefully insert the head end of your carriage bolt into the bottom of the crankcase so that the domed head is centered on the back of the crankshaft and the edge of the domed head is under the bottom edge of the connecting rod. Now use the carriage bolt like a pry bar, to pull the connecting rod back and off the crankshaft pin. There may be some resistance just as it is about to come off. Apply a bit more lubricant and using a bit more pressure on the carriage bolt, rotate the prop about 10-15 degrees and the connecting rod will come off the crankshaft pin.

Flush out any small filings of brass or aluminum using Pacer Degreaser. These small pieces won't be missed by the connecting rod but you don't want them getting into the engine or bearings later on.

Question: I need to change the Piston in my VMAX ABC type engine. How do I remove the Piston without damaging anything?

Answer: First of all you need to remove the cylinder (sleeve). Please see the How to Remove the Cylinder (Sleeve) procedure below.

Note that in nearly 100% of cases, when replacing the piston in an ABC engine, the cylinder should be replaced also. They are generally sold as a set.

Once the cylinder has been removed you can remove the piston complete with connecting rod and wrist pin. There is a trick to this. Please put away your hammer, vice grips, pliers and cutting torch and obtain a carriage bolt that is about 3/16" in diameter and about 3" long. Carriage bolts have a rounded dome like head and are available in pretty much any hardware store.

Securely tighten the prop nut and prop which will serve to pull the crankshaft as far forward in the crankcase as possible. Remove the crankcase backing plate. Lubricate the bottom of the connecting rod where it attaches to the crankshaft pin. Use Pacer After Run Oil or other lubricant. Remembering that there is no cylinder in the crankcase, carefully and slowly rotate the engine 2-3 times by hand and stop with the piston at top dead center (highest point) in the crankcase.

Carefully insert the head end of your carriage bolt into the bottom of the crankcase so that the domed head is centered on the back of the crankshaft and the edge of the domed head is under the bottom edge of the connecting rod. Now use the carriage bolt like a pry bar, to pull the connecting rod back and off the crankshaft pin. There may be some resistance just as it is about to come off. Apply a bit more lubricant and using a bit more pressure on the carriage bolt, rotate the prop about 10-15 degrees and the connecting rod will come off the crankshaft pin.

Flush out any small filings of brass or aluminum using Pacer Degreaser. These small pieces won't be missed by the connecting rod but you don't want them getting into the engine or bearings later on.

Question: I need to change the cylinder on my VMAX ABC type engine. How do I remove the Cylinder without damaging anything?

Answer: Install a propeller and tighten it securely. Remove the glow plug and brass glow plug washer. Remove the head. Rotate the propeller until the piston is at the bottom of the large exhaust port. Position the brass glow plug washer on top of the piston so that about 10-15% of  the brass glow washer protrudes into the exhaust port but not beyond the outside diameter of the cylinder. Hold the engine level and rotate the prop so as to raise the piston. The brass glow plug washer will catch on the side of the exhaust port and you can then use the leverage of the propeller to literally lift the cylinder out of the crankcase.

Note that in nearly 100% of cases, when replacing the cylinder in an ABC engine, the piston should be replaced also. They are generally sold as a set.

Better Answer: The trick to this is NOT to use vice grips, pliers or other tools on the cylinder itself. Follow the procedure outlined in the Answer above. The brass washer is softer than the plated cylinder and the piston so that it will not mark either when used as a lifting wedge. The propeller provides plenty of convenient leverage to literally lift the cylinder right out of the crankcase.

If the cylinder will not move using this technique try the following: Install the engine in a test stand or clamp GENTLY in a vice (emphasis on GENTLY!). Keep uplifting pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. This will expand the crankcase somewhat allowing the cylinder to move more easily. Increase the pressure on the prop and the cylinder will move upwards and out of the crankcase.

If the cylinder will still not move after heating the crankcase try the following next: Leave the engine clamped down. Get a can of Pacer Degreaser. Use eye protection and rubber gloves. Move outside. We are not going to use the Degreaser as degreaser per se. It has another quality that we need. It has a very high evaporation rate and cools whatever it is sprayed on. So we are going to use it to cool the cylinder liner after heating the crankcase. The heat will expand the crankcase and the degreaser cooling will contract the cylinder allowing the cylinder to be removed from the crankcase. It is important to DO THIS OUTSIDE. Do NOT USE your heat gun and your degreaser at the same time. Keep uplifing pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. Don't go overboard. Just get it nice and warm. TURN OFF THE HEAT GUN and set it aside at a safe distance. Now take the degreaser and spray a good blast into the cylinder on top of the piston. This will cool the cylinder quickly. Now increase the pressure on the prop and the cooler contracted cylinder will move upwards and out of the heated expanded crankcase.

Question: My VMAX 46 or 52 or other VMAX ABC type engine is very tight at top dead center particularly just out of the box. It is so tight that I hear a clicking noise at the top of the piston travel and it is very difficult to turn it over by hand. Is something wrong? What should I do?

Answer: No nothing is wrong. Please review your instruction manual and in particular the BREAK IN section.

Better Answer: ABC engines have a tapered sleeve which creates a tight fit around the piston at top dead center. The tightness is quite pronounced when the engine is new and cold. As the engine warms up, the sleeve expands and the fit is not quite so tight. The top of the sleeve gets much warmer than the bottom and hence it has been made narrower to allow for more expansion while retaining compression.

Your instruction manual contains specific information related to your engine. The BREAK IN section is very important. The VMAX 46 and 52 engine manual has a note that is boxed to draw attention to it. This note is located on page 3 of the manual in the top left corner and deals specifically with the question of tight fit at top dead center. The note reads as follows:

THIS IS AN ABC ENGINE. IT WILL BE VERY TIGHT AT TOP DEAD CENTER. THIS IS NORMAL. AFTER THE FIRST FEW RUNS IT WILL LOOSEN UP SOMEWHAT BUT REMAIN TIGHTER AT THE TOP WHEN COLD THROUGH ITS LIFE.

We cannot overstate the importance of reading the entire manual before attempting to operate your engine.

Question: I am not planning on using my engine for a period of time. What should I do before stroring it?

Answer: Remove all methanol from the Engine. Apply a generous amount of After Run oil. Turn the engine over by hand to ensure the After Run Oil works its way to all components. Seal the engine in a plastic bag.

Better Answer: Remove the glow plug and carefully put 6-10 drops of Afterrun Oil (Pacer After Run recommended) into the combustion chamber and another 6-10 drops into the carburetor inlet. Turn the engine over by hand 10 times. Do this a second time...  apply another 6-10 drops of After Run Oil into the carb inlet and combustion chamber... turn the engine over by hand 10 more times. Finally put the engine into a plastic bag, squeeze the air out of the bag and seal it.

Question: What gives with Model Airplanes Engines? What's a 2 stroke? What's a 4 Stroke? What do you mean by Glow as compared to Gas? Now there are electric motors being adapted to replace engines... how the heck do I choose what is right for my model?

Answer: Well, answers to this can take a bit of explaining. Here is an overview.

2 Stroke (sometimes called 2 cycle)

• Is what the majority of current modelers mean when they say "Model Airplane" or "Glow" Engine
• Noisy screaming type of sound that must be carefully muffled and never sounds like the real thing.
• Uses Model Airplane Fuel (alcohol, oil, nitromethane and additives)
• Uses a Glow Plug hence the term "Glow" Engine.
• Generally the cheapest, lightest, most powerful engine for the money.
• Referred to by displacment in hundreds of cubic inches (or in cubic centimeters = cc)
• Imperial measure is cubic inches and a slang has developed
  • .40 cubic inches is referred to as "a 40"
  • .90 cubic inches is referred to as "a 90"
  • 1.20 cubic inches is referred to as "a 120"
• Generally range in size from .049 to 1.80 although some smaller and bigger engines exist.

4 Stroke (sometimes called 4 cycle)

• Has become more popular since the 90's with those wanting quieter more realistic engine sound for use in semi-scale or scale models.
• Quieter more familiar engine sound when in the air. Much more realistic for scale flying models. Sounds much more like the real thing.
• Uses Model Airplane Fuel (alcohol, oil, nitromethane and additives) although special blends with more or less oil and more or less nitro may be required for some engines.
• Uses a Glow Plug hence the term "Glow" Engine can be used for either 2 stroke or 4 stroke engines
• Generally costs more, weighs more and gives less power for more money than a 2 stroke engine of similar size.
• Referred to by displacment in hundreds of cubic inches (or in cubic centimeters = cc)
• Imperial measure is cubic inches and a slang has developed
  • .52 cubic inches is referred to as "a 52"
  • .91 cubic inches is referred to as "a 91"
• Generally range in size from .25 to 2.50 although some smaller and bigger engines exist.
• To get the same power as a 2 stroke, add on about 30-50% in size. This is a very rough rule and does not consider weight and torque issues but it is a good guide.
  • A model calling for a 2 stroke .46 would require roughly a 4 stroke of size .60-.70
  • A model calling for a 2 stroke .61 would require roughly a 4 stroke of size .80-.90

Gas (sometimes called Ignition Engine)

• Has become more popular for use with big models.
• Quieter more familiar engine sound when in the air. Much more realistic for scale flying models. Sounds like the real thing  because it pretty well is the real thing!
• Uses Gasoline. Special oil or additives may be added to the gas in some cases. Gas is 25-50% cheaper than Model Airplane Fuel.
• Uses a Spark Plug hence the term "Ignition".
• Often adapted by the manufacturer from some other purpose such as a weed eater, leave blower etc. Although the engines end up quite different with regards to fuel supply, ignition, prop adapter and flywheel etc, they usually started with an existing product and adapted from there.
• Seldom used on smaller models and nearly always used on big models due to the higher weight of the engine and ignition system.
• Generally costs more, weighs more and gives less power for more money that a 2 stroke engine of similar size. May cost and weigh more than a 4 cycle Glow engine.
• Referred to by displacement in cubic centimeters (cc) (or in cubic inches but almost universally now in cc)
• Metric measure is cubic centimeters (cc) and the cc is nearly always noted in referring to these engines
  • for example "30 cc"
• Generally range in size from 20cc to about 65cc although some smaller and considerable numbers of bigger engines exist.

Electric Motors (both brush type and brushless type)

• Have become more popular since 2000. Increasing in popularity
• Just as a combustion  Engine needs and is succesful depending on the type of fuel it burns, an electric Motor needs batteries.
• As battery technology put more and more power (run time) into batteries of a certain weight (we call this energy density) electric powered flight is starting to take off (literally)
• Generally brushless motors are taking over. They can be very expensive when coupled to a suitable electronic speed control and a good set of NiMh or LiPo batteries.
• Main advantage is quieter and no mess. No fuel to buy.
• Main disadvantage is price and flight time per charge.
• They will continue to improve and be more popular in time.
• The rating system is not yet standardized so it is hard to compare apples with applies. Generally if a model calls for a .40 two stroke engine, modelers need to select an electric motor that can provide similar power in order to have similar flight characteristics. This can vary widely by motor type (brushless is better), battery type, speed control and wiring.

Please note that to this point this article makes no attempt to advise on if a particular model can be adapted to accomodate a different type of power system. For some considerations related to fitting 4 stroke engines into a model please search on "Four Stroke" for further assistance.

Question: Can I use a 4 Stroke engine on my VMAR ARF model?

Answer: In most cases, Yes.

Better Answer: There are some things to consider here. First of all if the model has a cowl it will usually have a power module consisting of a removeable forward firewall and a set of engine mounts. These engine mounts can be oriented in many different ways so you can select the orientation and separation of the mounts to suit your engine. It is also very easy to work on with this setup because the forward firewall is completely removeable from the model. So... VMAR models with a cowl and power module probably will be able to accomodate a 4 stroke engine. Conversely... models without a cowl and power module usually have a factory installed engine mount and a fixed firewall only and may be more problematic when trying to fit them out with a 4 stroke engine. It is safe to say that if the model does not have a cowl and power module there may be significant work and mucking around in order to install a 4 stroke engine.

4 stroke engines are not as standardized as most 2 stroke engines... some have the carburetors at the front, some at the back. Some have valve pushrods running up the front of the crankcase... some up the back. As a consequence, 4 stroke engines vary quite a bit in length (i.e. the distance from the prop shaft to the back of the engine) within a particular size. Although for example a 2 stroke .46 from one supplier will be very similar in external size to that of a 2 stroke .46 from another supplier... it is not necessarily the case when comparing 4 strokes. A .52 four stroke from one manufacturer can be quite different from a .52 four stroke from another manufacturer. There is no way we can be aware of all the different sizes and shapes of four stroke engines in the market and modelers should be checking with the engine manufacturer for sizes before assuming that the engine will fit into any particular model. Once you know the length of the four stroke engine that you are considering, place the cowl on your model. Then measure from where the back plate of the spinner will be to the front face of the removeable power module firewall. Subtract about 1.25" from this distance and then compare the result with the length of your four stroke engine. Engines that exceed this length will significantly protrude from the front of the cowl and should be trial fitted carefully before purchase.

In some cases, we are pre-cutting cowls to make installation of our recommended 2 stroke engine go as quickly and easily as possible. We do stock blank (not cut) cowls for those who wish to use a differnet 2 stroke engine size (for example a .61 instead of a .46) or a 4 stroke instead of a 2 stroke or want to go with an inverted installation or other orientation when we may have assumed a 90 orientation when pre-cutting the factory cowl.

Lastly, we have some models that do not use a cowl per-se and do not have a power module but may look like they do. For example the F4U Phantom and Skyhawk and Arrow Tiger have a shaped and fitted nose section but not a cowl and we have not recommended 4 stroke engines for these models at all. Again, if we do not use a cowl and power module on a model... we may be significant work and mucking around in order to install a 4 stroke engine.

Please note that to this point this article makes no attempt to explain the differences between the different types of engine systems. For some of the pro's and con's of 2 stroke and 4 stroke engines please the article included below:

Question: I have pulled the back plate from my engine and I can see rust on the back of the crankshaft and on the rear bearing. Is it OK to run the engine like this? If not, how can I remove the rust?

Answer: It is not a good idea to run the engine until the rust has been removed. The rust is very difficult to completely remove without disassembling the engine but you can do a reasonable job with Pacer After Run Oil and Pacer Degreaser. Commercial rust removers have been used but can cause problems with gaskets, O-Rings and aluminum so we do not recommend commercial rust removers unless you completely disassemble the engine.

Better Answer: Rust does two things, it erodes and pits the smooth surfaces of the crankshaft and bearings and rust flakes off as a gritty abrasive when the engine is operated next. Once the rust has formed there is nothing much you can do about the damage that has already been done to the surfaces. However, the damage may not be critical if caught early. The important thing is to remove what rust you can before it flakes off and works its way through the engine as an abrasive.

Remove the prop nut, prop washer and thrust washer so you can see the front bearing. Use Pacer Degreaser to clean out the engine. Read the cautions on the can. Work outdoors and wear eye protection and gloves. Spray the degreaser inside the crankcase first while holding the engine slightly nose high so that as you spray the back of the crankshaft and the rear bearing, the excess degreaser washes back and flows out the back of the engine.  This will knock loose and carry away some of the rust. Then hold the engine nose down and spray the front bearing. Let the engine dry.

Once the engine has dried off, thoroughly douse the rear bearing, front bearing and crankshaft with After Run oil. Drip after run oil into the rear bearing from the back of the crankcase, into the crankshaft area through the carb inlet and into the front bearing from the front of the engine. Rotate the engine by hand 2 times and then flush all of the oil away using the Degreaser again. Flush thoroughly and let dry.

Repeat this process three times, each time rotating the engine by hand for a greater number of rotations. What you are doing here is using lots of lubricant as you rotate the engine and flake off rust. The loose rust ends up in the lubricant and then carried away as you flush with degreaser.

Lubricate the engine again with plenty of After Run oil. Let it sit a day or so before operating. Rotate the engine by hand 10-15 times and then flush one more time with Degreaser and let dry. Apply plenty of After Run oil, reinstall the back plate, thrust washer, prop washer and nut. Rotate the engine 2-3 times by hand.

You can now run the engine. This process won't undo any damage that the rust has already done but it will help to reduce the amount of rust in the engine and the abrasive action of the rust as it flakes off.

From this point on, make sure you use After Run Oil after each day of operation. See your Owners Manual for maintenance and cleaning information and review our Rust Prevention tips and our tips for long term storage of your engine.  

Question: Why is Rust a problem in Glow Engines: How can it be prevented?

Answer: Rust reduces the power and life of your engine. To inhibit the formation of rust remove all methanol from your engine and use After Run Oil after each day of flying.

Better Answer: Glow fuel consists primarily of methanol, lubricant and nitromethane. Methanol attracts water vapour. This water vapour condenses into water  inside your engine which in turn will cause rust to form on the steel parts of your engine such as the crankshaft and bearings.

Rust does two things, it erodes and pits the smooth surfaces of the crankshaft and bearings and it flakes off as a gritty abrasive when the engine is operated next. The erosion of the surfaces reduces RPM and increases heat and load on the surfaces. The loose rust that flakes off as a gritty abrasive induces wear on all the moving parts including the piston and sleeve. The end result is that RUST reduces performance (RPM and power) and reduces the life of the engine and leads to premature component failure. Bearings are particularly susceptible to failure caused by Rust. Crankshaft front bearing leakage and in particular crankshaft to conrod pin failure are also common problems caused by rust.

There are two simple things you can do to inhibit the formation of rust in your engine:

1) Avoid leaving methanol in your engine.

When you stop using your VMAX engine for the day, run the engine dry by pinching the fuel line feeding the carburetor and let the engine run out of fuel. This will burn up most of the methanol in your engine.

2) Use After Run Oil in your engine after each day of use.

Remove the glow plug and carefully put 6-10 drops of Afterrun Oil (Pacer After Run recommended) into the combustion chamber and another 6-10 drops into the carburetor inlet. Turn the engine over by hand 10 times. Reinstall the glow plug, close the carb and insert a small plug of wadded paper towel into the carburetor intake.

If you are not planning on using your engine for a while please see following information about storage of your engine:

Question: I am not planning on using my engine for a period of time. What should I do before stroring it?

Answer: Remove all methanol from the Engine. Apply a generous amount of After Run oil. Turn the engine over by hand to ensure the After Run Oil works its way to all components. Seal the engine in a plastic bag.

Better Answer: Remove the glow plug and carefully put 6-10 drops of Afterrun Oil (Pacer After Run recommended) into the combustion chamber and another 6-10 drops into the carburetor inlet. Turn the engine over by hand 10 times. Do this a second time...  apply another 6-10 drops of After Run Oil into the carb inlet and combustion chamber... turn the engine over by hand 10 more times. Finally put the engine into a plastic bag, squeeze the air out of the bag and seal it.