Sorry - I was little quick with the ole enter button the first time.

My question was --- is the basic layout of the head gasket the same for a 300ex and a 400ex/xr400 ( obviously, except for the diameter of the cylinder) I have a 300ex with a 385 big bore (85mm), I can't find a head gasket. My bore is the same as a stock 400ex/xr400 now, so I was wondering if the layout was the same maybe I could use it. Any help you could give would be appreciated.

Thanks
Bill

 

From what I remember they are different. Try Powroll for a big bore 300 gasket. It won't be 85mm but bigger than stock.

 

They're definately different...the cool thing is, the XR gasket will fit a 400EX and give it alittle more compression...and it's alot cheaper than a piston...lol

 

Update -- I finally ended up calling Cometic Gaskets directly. They looked through their archives and they had custom made several of those gaskets for Pro-Fab ATV (the guy who built my engine). Anyway, just told them I needed a 300ex head gasket with a 85.5mm hole in the middle and just like that, they stamp it out and send it to you. $22.95 plus shipping. May seem normal to some people, but to me, I had no idea you could get custom head gaskets!!

 

Me neither, that's very cool. When I go to a big bore stroker motor, I'll know where to go for gaskets!