My 701 raider keeps seizing the rear cylinder and im about to give up trying to find out why. bored to 84mm with milled head and msd enhancer with riva pipe. tried everything imaginable with carbs and front runs fine and rear fouls plugs and finally seizes due to heat.deep chocolate plug color but very hot. 300 on rear case near bottom after about 5 min.@65oo rpm...3d time...new sleeves, pistons, the works same prob..curious as to if i should change head to oring head and no gasket for more h20 flow around cylinders..... any help greatly appr. thx. seachaser22

call this guy, he is the machinist that does all the work for the local dealers. he is reall knowledgable.
jim bauer
werks engineering
757.340.3730

What kind of pistons are you using ?

REPLACE THE CRANK SEALS!!!!!!!!!!!!!!!!!!!!!!!

It does sound like an air leak. You might want to do an leak down test or just take 2fast advice..replace crank seals AND carb gaskets.

I don't think it's head gasket problem...but,put a new one on just in case.

Seals and gaskets...should cure the problem if you have thoroughly gone through carbs and jetting.

Mike

thx guys.... seals seems like a good reason.. any hints on how to go about pressurizing and testing this once i get new ones in.... using wiseco pistons...it ran really fast on full throttle.. like 7200 and real smooth... just not for very long..haha...would lean condition make plugs really dark? thats whats confusing me...starting a tear down now

you may want to stay away from wisco pistons, they are really for serious racing in which a rebuild after a couple of months is common. plus they have to be dialed in just right and broke in the same. stick with pro-x pistons...they make the oem!! and are a few bucks cheaper in cost. 124.00 bucks and they come with rings, clips and pins. the best think to do call jimmy, from my previous post... he can hook you up!! i.e. : presure test proceedure. with all the work you got in... doing your homework may save you in this rebuild! good luck

Use PRO-X pistons,I wouldnt put wiseco in my weedeater.

thx guys..calling jim tomorrow

hey sprink, thanks a million... jim had a wealth of info... he thinks evidently the guy i bought the ski from routed the water the wrong way through the riva pipe and it was going in the head and out the exhaust....backwards... let ya know me progress. thx'