Shaving the head - how much?

[Robgsxf750]

So I'm going to shave the head a bit to increase compression.

Anyone done this on their bike?

I've been told various things from a couple of thou' to twenny thou'.

Funnily enough the suzuki dealership where I take my bike don't want to suggest anything. They flat out refuse.

I got a guy that can take 10 thou off for $40 which I'm pretty happy about. Doesn't outsource so that's good too.

[hardlydangerous]

.010" wont do much for you. You will get better performance with fresh rings in a fresh bore.

The dealerships won't touch it because there is a lot more to it then just shaving the head.

In order to check the clearance you need to used modeling clay. lay it on the piston crown, put the head back on and turn the engine over. The valve will indent the clay and tell you how much room you have to play with. Normally you want aprox .050" clearance but every engine builder has their own prefereance.

A few other things that com into play is the cam timing and cam chain.
when you lower the head to lenghten the cam chain. Often the cam chain is too long yet too short to take a link out.

Normally when you increase the compression your going tom want to back off the cam timing slightly, without adjustable cam gears this is pretty tricky unless you know a shop that will modify the OE gears to be adjustable.

Last is heat and detonation.
With higher compression come much hotter running engine that is much more likely to detonate. Be ready to alter the ignition timing, jetting, spark plug heat range etc

If you decide to go with the machined head, you will want to invest in a EGT/CHT guage to monitor the jetting, combustion temps and cylinder head temps.

[StevieB]

My barber will shave your head as close as you want him to...

[Robgsxf750]

Can he take off ten thousand?

[arsenic]

Rob, we've had discussion about things you want to do to your bike and I'm with you on wanting to make it as bad arse as possible. Their are a few things I did not do the the dream project engine. One of them is decking the head. For the gains you will see on an engine that is already so not meant for this type of stuff. You're putting yourself in a world of hurt. Just my opinion.

[Robgsxf750]

Sweet, all i needed to know.