The squish clearance is the distance between the piston and the head. Removing base gaskets will reduce this distance, but also changes some other things such as port timing and compression ratio. If you have the head machined to reduce the squish, this will keep the port timing the same, but increase compression. If you want to keep the same compression ratio you also need to have the machinst remove some material from the combustion chamber to correct it.
The exact figures need to be calculated, and first up you need to take a squish measurement before you get any work done. Usually best combined with a complete top end teardown.
I have set my 250 up to use a single 0.5mm gasket which leaves the piston above the exhaust ports a bit at bottom dead center. This is just to compensate for the porting on my cylinder being orientated towards top end, so allows the power delivery to remain closer to stock with a little top end bonus. I basically configured for the most useful spread of power over max hp.
|