Alright so my i got this idea while at work the other day and was thinking if it is possible to shave the heads on my f4i... and cam options... anyone done it? clearance between the piston and head or spark plug? any input would be great.. Thanks

 

shave the heads... ? theres not anymore that can be removed from the piston dome area really, you can get thinner head gaskets and cams and all that crap to "build" a motor out there, although for an f4i? good luck finding them. hrc sells the best kit but usually only makes current model parts. actually wow, they still do make parts.

http://world.honda.com/HRC/products/...f4i/index.html

what are you lookinf for? if it's just more power go bigger, unless you're racing in some kind of classics race that is limited to 600cc although there are no current class that would allow an f4i right? what exactly is your idea?

 

Of course. You can lighten your flywheel, knife edge your crankshaft, get bigger pistons, re-degree your camshafts, port and polish the head and do many other things to increase power. But the thing is that you will end up with a very high revving, peaky engine. Sure, it might have 110-120 hp but it will idle high, run hot and will be very unhappy unless you are throwing it through corners at 10k, or running a quarter mile. It will not like to sit in traffic. Besides that, you probably wouldn't be able to sell it and get your money back. If I built a motor for my f4i it would
cost as much as I paid for the bike in the first place.

 

Really, you can knife edge your crank? Not even AMA SBK has "knife-edged cranks" and those bikes put out prodigious power. And lightened flywheels? Can you show me the flywheel on a sportbike? Any current model bike please. And what is the benefit of putting a bigger piston in a sportbike motor? Maybe you mean lighter, or maybe tougher??? Port/polish is very viable on bikes, although if your doing this you need new cams, not re-degree'd ones as that would be a compromise. Just get an HRC kit, btw, millenium tech will rebuild a motor with higher comp for about a grand.

PS-the "rule of thumb" is 8lbs lost = 1hp gained, the f4i could lose a lot of weight

 

What is the benefit of bigger pistons? More power. Yes, knifeedging a crank or a lighter flywheel won't make any more power than stock. It may spin faster but a built motor will inevitably fail. But the point is that I acknowledge it, I am not here to make people feel stupid for wanting to do whatever they dream of to their bike. Unless you race your bike, stunt it or ride it a respectable amount, whatever you do to it will be a waste. Every rider can improve their riding skills, that is the most important.

There are many f4i's, modifying it makes it yours. Some poeple chrome their rims, others would rather spend it elsewhere. Yeah, it's just a f4i, so you will spend a lot for a little power. What is more valuable is the expieriance gained from mechanical work. So i'm here for everyone that is nervous about their valve job an needs a nudge to tell them it's simple. I'm not here to tell people not to "waste" time, money, whatever, doing whatever idea they get. I'm here to tell them it can be done and encourage them to document it for others to learn from.

 

Wow Mc, that is an awesome response, I do need to apologize for my negative responses.

btw though, sportbikes need lighter pistons, not bigger. just sayin!

 

You do come on a bit aggressive, and some people that ask question do get offended, but we will get used to you. Johnny

 

mc has the right idea.. im not looking to try and get more power out of it.. im the kinda guy that wants to try something new and original for myself. I'm pretty good at mechanics and dont mind getting into things... im just trying to see if its possible and if it is id like to try it..

 

My buddy did it on his r6, I helped him and we did check the piston to valve clearance to make sure the valves would,nt hit. We also did a volume check to determine the compression ratio. Any way the results after shaving 20 thousands were an extra .5 on the compression ratio and from a 10.90 on the 1/4 to a 10.40. We also cleaned up the head ports. Johnny