My 99 400EX is due for a top end. I've owned it for 2 years, and I knew when I bought it, I would have to do a top end on her. Its still on a std bore, with the OEM piston. My question, is what brand of piston and rings would you recommend. Some of the brands I've considering OEM, Wiseco, Pro-X or some other e-bay brands.. . Unless there are cylinder issues, I plan on keeping it at the std bore. Since its cold, now is a good time to tinker in the garage.

Thanks for the help.

 

Namura or wiseco... either of those you can't go wrong...
wiseco you'll pay more for the name.

take the cylinder to a shop and have them measure it and make sure it is good.

 

just dont bore it to a 440. I believe the next size down is a 418 which is much better. The 440 pull the head studs right out and blow head gaskets unless you buy the 80 arp studs.

 

wiesco.

 

86mm is stock , 87mm is a 416 , 88mm is a 426 , 89mm is a 440 , most companies will go n 1/2 mm to , which is .020

 

<div class="FTQUOTE"><begin quote>Originally posted by: 450speed

just dont bore it to a 440. I believe the next size down is a 418 which is much better. The 440 pull the head studs right out and blow head gaskets unless you buy the 80 arp studs.</end quote></div>

I bought a well used 440ex last year from a guy who obviously beat it pretty bad,had to fix and replace a lot of parts, frozen brake calipers, cracked a arms,bent rim,totally burnt out muffler,etc. Surprisingly enough,this thing starts and runs like a new one!! My son and I have rode it, even raced it once, and it has not given us one bit of trouble from the engine,tons of power and still starts and runs great. Maybe the guy I bought it from built it right with the bigger studs, or we've been real lucky, but so far I have not seen the problems everyone else seems to be seeing.

 

the wiesco pistons are made differently (better) they are a forged piston. the numara pistons are cast which makes them weaker.

 

I'm planning on keeping it std (stock) unless the cylinder requires a boring. It curently runs good, just smokes... so I'm assuming its time to do a top end.