I have a pro x 310 cylinder. The stock studs have been cut on the front and it's hard to get them to start. Does anyone make a proper length stud for this cylinder? Also my motor has a long rod, but no spacer? What piston do I get? I'm guess there's a piston with a different pin position to compensate for the rod?
yes you need to run a shortrod piston and spacerplate with a longrod crank.you will also need the longer studs...they dont make a longrod piston over 68mm's
Motor ran when I took it apart. Part # on the rod for pro x says it's a long rod. It has no spacer plate and bore is 72mm.... So that means that there is a 72mm piston out there setup for a long rod and no spacer plate.. I attached a picture of the motor, the rod that's in it, and what pro x says it is.
That's one of the reasons people use the spacer plate/86 piston set up. 86 has more sizes to choose from. It is a strange situation though. If i'm not mistaken, is there a yamaha piston you can use in place of a 86 250R piston? Is it possible there is a different make that could be substituted for a 87-89 250R engine piston ?
Last edited by meathead321; 07-24-2018 at 04:13 PM.
I'm trying to get more answers on this 86/long rod/spacer plate. Is there port timing issues with that? some say yes, some say no, some say yes, if you have had cases cut or cylinder cut down. Pretty sure all my stuff is stock, just bored and ported.