Techie question. Engine.

[Goines]

One for you gearheads.

How would the S feel with slightly increased compression? I have a pal who works in a mechanical shop and he suggested some 'milling' of the cylinder head.

What about some polishing of the intake and exhaust 'channels'. Would that do anything noticable?

[arbik]

its already a high compression motor. Depending on what kind of gas is available for you, this might open up a can of worms you dont want to deal with.
In kalifornia, we get terrible gasoline, even the "high" 91 octane. During the summer time, the reformulated gasoline used to knock like crazy in my stock motor, so higher compression will make this even worse.

-arbi

[Goines]

Originally posted by arbik
its already a high compression motor. Depending on what kind of gas is available for you, this might open up a can of worms you dont want to deal with.
In kalifornia, we get terrible gasoline, even the "high" 91 octane. During the summer time, the reformulated gasoline used to knock like crazy in my stock motor, so higher compression will make this even worse.

-arbi

We have nice 98 Octane gasoline so 'knocking' won't be an issue.

[edit] A friend of mine have around 12,5:1 in his tuned GSXR1100 and no problem with the gasoline.

[roger albert]

Well, bikes with high comp pistons and with mild portwork (like Eron's, for instance) seem to respond really well. You may or may not get the full effect w/o proper mapping, but would certainly benefit some. Whether you have clearance for significant milling on this head, I don't know. That has to be verified carefully. Would be cool to hear from anyone who has undertaken milling on these.

[smallj]

I picked up some 12.1 pistons last winter and the bike responded well. I've got over 10K miles on them without incident or knocking. I have never dyno'ed the bike but seat of the pants makes for big smiles and bigger wheelies. Very expensive to have the pistons installed and balanced. Was it worth the $$$? Probably not, but by the time i figured out that it was going to cost me $2500 USD, it was a bit late. Now I own one of the fastest S's on the road, if only I were a faster rider...

[Dr. Curve]

A full .030 of a inch. No problem. This will need no after-mapping, and no fear of valve clash will be warrented. Up to .050 of a inch if care is taken to keep perfect timing (not advanced even one degree) and only run 93 plus, name brand gas. More than .050 means that the cam tensioner will be taxed a bit. Also don't forget to match the injectors if you can get your hands on a few to chose from. Find two that mist the most as compared to others.......and the same compared to each other. You must go to a injector shop that can meter injector flow under specific pressure........with regards to mist shape, and ammount released. Rich mist, equal squirt injectors plus .030 off the head and you will be up at least 3HP at the rear.

[Goines]

Dr.Curve: You think milling the head down ~1mm would come out with no risk of valve damage? (0,03in=0,0762cm) Oh well. I guess I'm off to the shop and get a half a millimeter off it for starters.