Originally Posted by
Grinder
Hi. I'm sorry to hear about the piston problem. The Kangaroo has a microcast piston, and it is more likely to have a problem like that. I have seen that happen to them. I suspect that the engine was over revved before it was fully warmed up, or run too lean before it was fully broken in. I suggest that you replace the piston, and sleeve with a new one if possible. Usually when the piston gets scratched, the engine will not idle, and loses power.
You will still have more power than a stock Kangaroo with just the modified crank, but the modified piston, sleeve will make it even better for sure.
If you feel that the engine is running fine, you may want to continue to run it. Did the scratch damage the oil rings in the piston?
Hey Uriah,im having the same problem too with my one race old 35+21.what actually happened was i was on the straight and suddenly the engine died! I thought i broke a rod but when i opened the backplate it wasnt the rod.wen i opened up the engine at home,the piston had an inch scratch like fulcrum2 described.i assembled the engine back together and ran it again,the engine kinda lost power and the temperatures were abit unstable.in addition,the compression isnt that good either.but im not gonna give up and try to run it one last time before deciding to rebuild or get a new engine
