S3 Race 250 Port Matched Cylinder and Head

[(F5)]

Well I run my race 50 at 0.5mm & at 14000 it almost grazes the head. If I reuse the double base gaskets too many time it just makes a noise.

But clearly the stroke is much larger on the 300. The other consideration is the MSV, which can be alleviated by taking some squish area out, but it isn't that big so I don't think its a problem & revs low so another lack of concern.

The closer you can run the head & piston the better (obviously without bumping the two together). Any mixture trapped there is lost to the cause, & the further away the less the piston gets the cooling effect of the head.

But lets not get too worried about it. The 300 has stacks of power, just closing the gap up should aid better combustion & thus fuel economy.