Piston Knocking

[yfzrider310]

Ok after having one of my good buddies rebuild my blaster down to the cases to install some new shift forks we realized that the piston would knock at idle. Now I have heard that a person should replace there piston after this happens. Also I was wondering if anyone has a good explanation for why this would happen. Thanks a lot.

[C-LEIGH RACING]

Originally posted by yfzrider310
Ok after having one of my good buddies rebuild my blaster down to the cases to install some new shift forks we realized that the piston would knock at idle. Now I have heard that a person should replace there piston after this happens. Also I was wondering if anyone has a good explanation for why this would happen. Thanks a lot.

#1
Piston to cylinder clearance to great
#2
Over revving the engine
#3
Riding it on the highway & revving it out in the gears
#4
Dirty air filter & dirt eating up the piston ( more than likely a K&N )
#5
Forgetting to turn the petcock on & running out of gas
#6
Stock carb with oil injection still hooked up & to big of a main jet causing the engine to get to much raw gas
#7
lot of hard riding, idling, hard riding, idling & engine getting to hot
#8
Diving a hot engine off into a creek or stream crossing, its a 4 wheeler not a submarine.
Neil

[mdebuck]

a bit cocky above but its more than likely runnin to lean of a gas....run maybe a higher octane fuel if you don't have a block off kit and if you do have a block of kit and your runnin 40:1 or leaner then try 35:1