I knew I remembered something Ivan posted about this on the US FZ1OA forum years ago:
07-31-2012, 01:20 AM
Using the R1 race gasket will give a compression ratio around 13.3-1.... this will still run well on 93 octane pump gas.
The FZ-1 stock gasket is appx .032" thick and the R1 race gasket is .020".
Using the R1 stock gasket will give 12.4-1 compression...
Lowering the head (using a thinner gasket or milling) will cause the cams to need to be re-degreed due to adding more slack in the cam chain.... the FZ-1 has slotted sprockets, so no need to buy a set.
This is the easiest way to increase compression... for the rpm range that this engine runs, the added compression will not cause the powerband to end early.
Using the gasket and setting the cams to 107in/101ex will give great results... using 105in/100ex will give better midrange at the expense of some top end.
Stock cam timing is 105/105...
105 on the exhaust doesn't really add any top end as compared to 100ex, but costs some midrange.... this is another area that this engine is detuned.
The good power cam timing window for 5 valve Yamahas is pretty narrow...
Increasing compression will give more power across the entire rpm range, but in order to make the most increase across the range, an ignition module becomes necessary as well as re-degreeing the cams.
A Yosh full system is a necessity as well due to the need for the longer header tubes to make the midrange.
Might as well clean all the valves and replace all the valve seals while you are in there.
Ivan
Original thread here:
http://www.fz1oa.com/forum/forum/fz1-fazer-owners-association/exhausts-carburetion-performance/gen-2-exhausts-fueling-performance/126444-squish/page2If you join that site and do a search using 'R1 head gasket' as the search words, you will find quite a few performance-related threads which should answer your question.