Question: When I try to change the throttle setting I find that the throttle barrel is very stiff or jammed in position. What is causing this and how do I resolve it?

Answer: This does not occur often but can occur when any sort of debris gets into the carb and lodges between the rotating barrel and the carb body or in the slot that is located in the rotating barrel into which the idle stop screw engages. It can also occur when debris scores the barrel or carb body or the edges of the idle stop screw slot.

It most cases it is resolveable while in some cases it requires parts replacement.

Procedure:

First of all make sure that the servo and control linkage between the servo and the carburetor are moving fully and freely.

Secondly make sure the prop is balanced and that you do not have a vibration problem. We have seen out of balance props cause extreme vibration that will cause the carburetor rotating barrel to oscillate rapidly and jam the barrel.

If these preliminary checks do not solve your problem you will need to inspect your carburetor more carefully as follows:

Please read these instructions from beginning to end twice before taking any action.

a) Consult the Owners Manual and Read Me First sheet which came with your engine. If you have misplaced these documents you can download a copy of the manual from the support section at www.richmondrc.com. See the VMAX section of our Knowledge Base.

b) Consult the exploded 3 Views in the Owners Manual (usually found on Page 6).

c) Loosen the cinch bolt nut (see 2090) and remove the carburetor.

d) Apply oil or after run oil to the carb rotating barrel.

e) Remove the idle stop screw (see 3080). Examine the end of the screw carefully. It should not have any burrs or nicks. If the end of the screw is irregular in shape or damaged in any way the screw will need to be replaced.

f) Carefully remove the carburetor rotating barrel complete with throttle arm. (see 3040). Watch for and retain the spring (see 3030). Take note of which way the spring is tapered and how it is positioned.

g) Carefully examine the rotating barrel and the carburetor body. Remove any debris. If the carb body or rotating barrel or the slot in the barrel for the idle stop screw are scored or have damage to their surfaces the carb and/or barrel will need to be replaced.

h) Flush the hole where the idle stop screw goes. Make sure no debris remains.

i) Reassemble the carburetor after applying Pacer After Run oil or other thin oil to the parts. Make sure the spring (3030) is inserted correctly.

j) Carefully screw in the idle stop screw.

k) Test for easy rotation via the throttle arm.

If after cleaning out any debris and carefully reassembling the carburetor, the problem persists, the carburetor or at least the parts noted above, will need to be replaced.