BannedCR500Riders.com

Can anyone tell me if the piston pin height on the 84-89 CR pistons is the same as the 90-01? Sounds like either my main bearings or lower rod bearing are going out and it's time for a rebuild on my 93. I would like to use a Wossner piston but they only make a piston for a 84-89 which I find odd because I thought in 89 the motors became close to the 90-01 in design. (long rod and taller cases)

I though somewhere in one of the threads this was addressed but I couldn't find it.

pin height was all the same. not sure why they list it 84-89. maybe the cutout was slightly different. could be a typo error on the wosner site im not sure.

oem + other brand pistons do fit all the years, possibly the intake window in the piston is larger than the 90+'s factory ones were, or the exhaust face of the piston is wide like the old ones were

okay that sounds good. What do you mean by exhaust face being wide? I assume you mean that the piston pin cutouts are narrow and just around the pin area so the exhaust port is fully closed and transfer flow doesn't escape out the exhaust?

bingo

I've compared them, the cutout on the older pistons is considerably larger and that is the only difference. put a '90+ piston in an older jug and you'll see a step where the opening is narrower than the port.

the pin that holds the ring is different on the OLD oem#, i know LA Sleeve has a couple of those in stock standard bore that he doesnt feel comfortable selling cuz they said they had issues