how many mm. is your spacer plate?

[Honda5]

I bought a 250r with pro-x 310 sleeved down to 265 and when I tore it down it had a 24cc dome in the cool head this seems like alot to me so I think they had used a thinner spacer plate which would make more compression the spacer plate is about 4.5mm I love the way it ran so I don't want to change anything. this just seems strange.

[brokeitin3]

4.5mm is correct for running the 86 style piston

[zedicus00]

that dome was prolly jus left over form when it was a real 310 kit. do a compression test im sure u could safely run a 21cc dome.

[Honda5]

ok thanks