Hey guys, how does an engine behave once it starts to wear out?

The past two races my Plus 4 has been doing ok. But it seems real boggy in low speed areas when the race is about 10 minutes in. After race warm up laps it seems real good and then as the race runs on it gets more and more weak on the bottom. The temps don't fluctuate too much from what we can tell. I've been thinking I'm having clutch bog problems but not sure why it would just start all of a sudden.

I know there are many, many more factors to it. With the engine head off and the flywheel off I can spin the crank and not be able to tell where TDC is. I think I'm at the point of needing a slight pinch. Anyway let me know your opinions.

This baby has been rock solid the past two seasons till now. I run buggy and truggy at most out of town races which are 3 days long. We do these races at LEAST once a month. But by my guestimate I'm around the 10 gallon + mark. The Plus 4 has been the only engine in my buggy since I purchased it from Houston.

Thanx
Chris