kx65 blown up

[1wheelr1]

hey , new to the site, so far alot of helpful posts so hopefully some good help on this one. i recently bought a 01 kx 65 from a guy who did not know what was wrong with it, so i took it home to find out it had a bog at mid to full throttle, come to find out the main jetting on the bike was too small to go with the fmf pipe he had put on it. so i up the main jet to a 230 (recomended by fmf) put a new br10 plug in it and some new 32:1 high octane fuel. bike runs like a rape date, for about 30 mins then dies. pulled the head off piston and walls look ok but there is some play if you bring the piston to top dead center you can push the head of the piston down maybe 1-2 mm , possible a wrist pin or rod main bearing problem?? Any others with this problem? And how can you tell if its from the air fuel mixture of the bike or if it was just coinsidence? help would be greatly appriciated :bang:

 

[Ol'89r]

bike runs like a rape date,
if you bring the piston to top dead center you can push the head of the piston down maybe 1-2 mm , possible a wrist pin or rod main bearing problem?? Any others with this problem? And how can you tell if its from the air fuel mixture of the bike or if it was just coinsidence? help would be greatly appriciated :bang:

That should be 'runs like a raped ape'. ;) :laugh:

Most likely a worn big end on the rod. Not uncommon at all with the KX65's. Especially one that has been raced or run hard. I doubt it was caused by the air fuel mixture. More likely to be improper gas/premix mixture or just simply worn out.

 

[JGrossijr]

KX 65's have a history of big end rod bearing failures. Most often the failure occurs on bikes where spray on air filter oil is used. There is no substitute for a properly oiled air filter. We have one with that lost the bearing when we were using spray on oil. Now we use Suzuki foam filter oil, run 40:1 with 190 main and have had no problems.

 

[Jasle]

like mentioned big end of the rod failed. Very, very common with the stock crank assy in a KX and a fast rider. The gap on the rod to bushings is pretty tight(read too tight). Either send it to someone experienced with kx's like crank works...or best bet is to buy a Wiseco hot rod. I have plenty of customers used spray on oil so we reccomended using 32:1 of a quality oil. I will not disagree that dip in oil is better...I just don't think it its a neccesity.