Ok brain trust, help me understand whatís going on here.
I just put a GS race piston in my Polini 177. It winds out fine, and pulls hard, but when it gets to the top of the rev range it stutters and surges, like itís going rich.
Using a 20/20 carb, 160AC, BE4 mixer. I started with a 120 main and have gone progressively down to a 110, but it still wonít rev all the way out. Donít think I want to go any leaner.
Starts fine, accelerates fine right up to 3/4 throttle. Temps never get higher than 250į.
Tried swapping carbs, same thing.
Plug looks good, compression is good, timing is dead on 18į. Brand new BGM fast flow tap.
What say yea?
Last edited by SoCalGuy on Sat Apr 27, 2019 7:53 am; edited 1 time in total