Has anybody put a CR head on a 250R. Would the be any difference. Has anybody heard of someone putting a yamaha phazer piston in a 250R. My friend was telling me he had one in one of the R's he had and it went like hell.

 

nver heard of people putting a CR head on before... But are you guys sure they even make an oversized phazer piston that big? A stock phazer is a 488 twin. It would have to be bored to a 499 for the piston to be equall to a 248cc piston. Im not sure about the exact mm but even if they make a phazer piston that big it would have to be the right lenght...

 

Why not run a cool head? People have used different pistons over the years but I would stick with the common off the shelf stuff. The phazer pistons start at 72mm thru 73.5 sames sizes as the 290-310 big bore kits. But it would also depend on the piston pin diameter, the distance from the piston pin to the top of the piston and the length of the skirt on the phazer piston. I remember a guy using a yamaha snomo piston a couple years back but it was pretty much a custon set up and the piston skirt lenth caused reliability issues. Otherwise it ran very hard.

 

People used to run either the Mungen or CR cylinders, before a better alternative came out. The CR cylinder was a powervalve, but needed the CR bottom end to work. I have seen some that had plates covering up the powervalve ports. The only reason to use these cylinders are that they offer wider tracts and more room for porting. Occasionally, you will see someone using a YZ250 piston, but other than custom applications I have never seen anyone using a snowmobile piston. Check out www.PlanetSand.com for more info on interesting 250R setups.