Hi, I have a 97`ZRT 600 with 5800 miles on it and plan on rebuilding the top end this summer, the SPX pistons are considerably cheaper the Cats and I was looking for any input on the pros and cons of these pistons. Hopefully someone who has put some miles on these pistons can help me out. Thanks in advance.

I've used them in my zrt6 with no issues, and I think the kimpex ones are ok as well. If you have that milage on the originals I'd say you are lucky that the ring locating pin hasnt come out and allowed the ring to turn on the piston which makes a big mess. The 600 zrt gives a little trouble there but with the low cost of the spx pistons they could be changed ever year or two. Often piston kits on e-bay for around 150 bucks I believe.

I've had one SPX moly coated piston I put into an older yamaha with good luck so far but it doesn't get a ton of use.

I've been trying to figure out if SPI and SPX are the same pistons and just branded differently. I put some 'SPI' pistons into my ZRT this past season and had extremely bad luck with them. These SPI pistons weren't moly coated either and I've from other people that they are suppose to be. The distributor was Gamma Sales as seen on STV occasionally. The number stamped onto these pistons looked more like a kimpex part number.

Seems like the tolerance was too large and the piston rocked back on forth and wore out the rings very quickly. In this thread you can see how much the ring is rounded out by the exhaust port.

http://www.arcticchat.com/forums/index.php...mp;#entry643396