oyster

Originally Posted by Str8 Jacket

That's a bloody good question!! And although I agree with Avgas to a degree it can happen alot sooner with a race bike.... Last year I did the whole Vic club winter series with no engine rebuilds and even forgot to change a spark plug. I went out this weekend with a brand new piston that had been properly worn in for just over 200k's and managed to seize it. Granted, the most likely cause is the fuel starvation to the engine but I guess what I am trying to say is that you can never be too certain with 2 smokers and I would always tend to waaay more conservative and replace piston & rings after a year/series....

In racing the piston will last about 1500 to 2500km. It depends on jetting, bore wear and how hard it's revved plus the general "thrash factor"
Most meetings are less than 100km so, it's good for a year or two for most.
Failure is fatigue, the skirt will crack and fall off.
Very messy results