I AM HAVING TROUBLE TUNING MY ENGINE IT HAS HAD ABOUT 4L THROUGH IT AND IT CHANGES TUNE HALF WAY THROUGH RACES FROM VERY RICH TO VERY LEAN. TEMP STARTS AT ABOUT 80C AND BY THE END OF THE RACE IT IS UP TOO APPROX 130-140C AND IT TAKES ABOUT 7 LAPS TO COME ON ANY TIPS. I HAVE PUT A NEW GLOW PLUG OSA8 IN IT BUT STILL THE PROB CONTINUES ANY ANSWERS?
I'm about the farthest thing from an experienced engine tuner...However, I'd guess that you have one needle to rich and one needle to lean...My first guess would be that the low is too rich and the top is just a little bit lean. If it's a hot day, 140C is only a little warm, right?
It sounds to me like an air leak. This usually causes the irratic tuning issues, and a lean/hot engine. Not sure if there is a "sealing an engine" thread, someone else may know of a step by step one out there.
Definately sounds like an air leak to me too. Look for fuel on the backside of the flywheel. If its wet the seal on the front bearing is shot. Look for a possible leak on the tank too or around the base of the carb or possibly the back plate....