I have a 86 and the last thing i needed to update was the crank. So i went just normal hot rod 87-89 long rod (not stroked). Use my 86 piston which is 68.5mm. Pretty straight forward. I used the long rod crank on 86 piston with 0.190 spacer plate and the two gaskets. I been cleaning the carb and messing with jetting wondering why it was lean... then finally did a squish test with 3mm solder (1/8th). Now i'm shooting for 0.40-0.50 and I got 2.43? So basically take away 2mm and i'm dead on at 0.43 so where the heck is the extra 2mm coming from ?..... Stock cylinder and everything and the guy i bought it off of had everything on it stock except the pipe and light. Even brake covers and gold rims etc was stock so I know he didn't shave metal off the motor head or cylinder etc... Even the old head on it was pitted and stock... where is the extra 2mm coming from i can't figure out....