RE: Tweaking TT .40 for max performance?
You have probably heard of the club"Expert's" method of engine break in. Run it slobbering rich for three gallons. The one person to avoid in a club is the engine expert.
An ABC type engine has no piston ring and relies on a tight fit at TDC for the piston/sleeve seal. If the piston/sleeve had this fit for the full length of the stroke the engine would never run. The sleeve has a tapered bore, loose at the bottom and tight for the last 1/4 inch or so at the top. When cold the piston/sleeve does not have the correct running fit. The correct fit/seal is achieved at operating temperature. As the engine warms up the sleeve expands slightly more than the piston and the fit settles in to it's correct seal.
If the engine is turned over when cold the fit will be damaged. During break-in the engine must be run at it's operating temperature and rpm using the fuel that will be used in its future operation, the engine must also have lots of lubrication at this time.
The only way to get the temperature and rpm up with a rich two stroke setting is to use a much smaller propellor than would be used normally.
When I break in a new ABC engine I mount it on a test stand. I heat the head with a heat gun to loosen the fit. I take it up to it's rpm and let it run a 6oz tank out. I shut it off rich. Let it cool down completely. Do this four or five times, it is now ready for use.
I am not the club engine expert.
Ed S