Vincent,
I run the TT25 (converted from RC) in my speed limit combat ships. It runs flawlessly. However, notice a few important things that can affect engine run:
- a custom-made venturi is seated tightly; any air leaks will give you problems with run consistency;
- needle valve used is Super Tigre assembly, also tight fit - it goes into the place that used to accept RC carburator mount bolt; this NVA is high quality and allows for smooth mixture adjustment;
- I run bladder tank, so there is no question of plumbing problems, tank leaks, fuel pressure, venting, fuel foaming;
- I use an APC 8-4 prop, which lets engine spin at over 12k RPM, which is where this engine "likes" to run; any attempts to get it to run at typical old-fashioned 8k - 9k RPM are futile without serious timing and other engine modifications;
- engine is mounted firmly using two F2D-style aluminum machined motor mounts directly to the center rib / fuselage; this minimizes vibration amplitude and maximizes frequency;
To summarize, make sure there are no air or fuel leaks anywhere, the tank is uniflow and plumbed correctly, fuel line is minimal length, prop is low-pitch (9-4 sounds good) and is well balanced, and the fuselage nose is rigid.
Good luck.
