Head Gasket= More Mid-range ???

[Miles]

Hey guys has anyone ever tried fitting a slightly thinner head gasket to create more compression ie: same air in smaller space? Just wondering as I am stripping mine down and thought I may as well do things like that whilst i'm there

[tk400]

It Is not quite that simple, That does increase the Comp ratio but also decreases piston to head. However usually there is around .9 or so standard so it has always been a proddy trick to remove the barrel to crankcase gasket which by memory is about .3mm and hence bring the piston to head down close to 0.6mm Kit spec squish. More is probably made through the better squich than the increased compression but whatever. However THIS PRACTICE IS HIGHLY RISKY as squish really needs to be setup much more accurately than this and on a per cylinder basis as once you get rod stretch at high RPM pistons will have intirmate relations with the head.
The best way to increase compression without decreasing squish is to deck the head, This however still brings valves closer to piston and I would then advise adj cam sprockets. cheers


Regards TK400

[Miles]

By deck the head, do you mean skim it? Was hoping this would be an easy mod to give good gains but it looks like abit of theory is needed

[tk400]

Yeah skim deck mill .....

[neil_cb125t]

the easiest thing to do is get the barrels planned - i go for .7-.8m head to slug measurement. using same gasket.

im runnig 444cckit and fcrs a few other little mods ( lighten and shot peened rods ported head ) and have 80hp at the rear with standard cams and ign.....still running a flywheel.

but really the gain will be very minimal.....