Originally Posted by
CH Ignitions
Jim,
Do you encounter miss fire on the stand when you on the ground on the stand?
From memory, yes. But will confirm later when I bench mount the engine again. It will be some time before I get to it.
Try to do the same test and go to 7.4v. This will put more power out of CDI.
I am pleased that it is safe to do so. I have two 18650 cells which will make up 7.2 volts (Lithium Ion 3.6 volt each). So will try them.
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2- the spark plug style . With exposed Portelan or NOT. Some times this makes a difference. Gap also need to be right. See if you can find the right gap that Sthill recommends for that engine.
I am using the spark plug that you recommended.
3- Carb adjustment, May act different in flight than on the ground. If the metering diaphragm gets bothered by the air around the hole.
Some people solders a little brass tube on the Metering plate and runs a tygon tubing in to the fuselage .
We don't think it is a carburettor problem, but will not rule out that possibility. This carb is a WJ57 and has a large rectangular atmospheric pressure sensing orifice (for the metering). Still could be vented to inside fuse like you suggest, but would be a bit complicated.
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Those will be my thoughts on this issue.
Adrian
Thanks Adrian.
edit: The spark gap recommended for this engine is .5 mm. See attached screenshot of the service manual.