Products - Frequently Asked Questions (FAQ)

Idling is irregular

Here's a checklist to help troubleshoot the problem:

Is the proper plug used?
If the compatibility between engine and fuel is poor, a stable combustion state cannot be created and this will affect the idling. Be sure to use the plug number recommended in the manuals for the engine.

Is the fuel compatible?
Although fuel compatibility is important, it is not as strict as plug compatibility. However, if a special application glow fuel is used, such as a fuel with an abnormally high nitromethane content or low oil content, stable idling cannot be expected.

Is an appropriate load applied?
If the flywheel is abnormally light, the idling may become irregular. Since stable idling cannot be expected when the shaft or primary reduction gear slips, such as due to a loose lock nut, it is necessary to check the related parts.

Is the needle valve set correctly?
The setting of the needle valve only at maximum rpm is insufficient. Once the needle valve has been set at maximum rpm, it is important to check that the engine runs steadily at all rpm ranges by operating the throttle.

Was the mixture control screw adjusted?
For a carburetor with the automatic mixture control mechanism, the carburetor should be set with extra care. Designed chiefly for steady idling and improved throttle response, the mixture control screw adjustment is meaningless if the carburetor is not set properly.

Is the muffler detached?
If the muffler is detached or loose, the idling becomes erratic especially when the muffler is detached from an engine fitted with a tuned pipe. The muffler should be attached properly since the same symptom may occur for regular engines.