high compression pistons and general help needed

[trick]

would just like some people who definately know what they're talking about. what are the benifits of high compresion pistons? also what does gas flowed head mean and ported head?
thanks alot guys

trick

[northwind]

Having spoken to the people who know what they're talking about, the JE high comp pistons get a really bad rap... Though it does seem that most that criticise the haven't actually tried them. The general concensus from the Socal guys is that Busa pistons are lighter and can give almost as much of a power boost with appropriately decked heads, and so they're preferable. Not quite so easy to fit up though, the JE ones from JHS are more or less drop-in while the Busa ones call for a piston hone and various playing about with either skimmed heads or thin gaskets for best results.

I'm still thinking about busa pistons when I finally get all the work I've done already tidied up and working right. More for the project than the results though.

Porting, polishing and gas-flowing are all pretty much the same thing- namely improving the way the air-fuel mix gets in, and the exhaust gases get out. You can probably add valve work to that mix.

[trick]

hmmmm, welll that sort of clears that up. any idea how much of a power boost someone would get if they put them in. i was thinking about the jhsracing ones, whats wrong with them?

thanks, trick

[northwind]

I don;t think there's anything wrong with them, just that they're heavy and expensive where Busa pistons would be lighter and cheaper. Then again, there's more setup work needed to get good results with the Busa swap so they've got that in their favour.

JHS's site has dyno charts for the mod but that also includes their special cams for the kit, which means it comes out pretty damn expensive.

[trick]

yeah i know, ive been looking at there site too. the parts themselves will be like 325 plus labour at my local garage (crescent suzuki UK - so i know the works good as all my work has been done there and theres NEVER been anything wrong), i wanna get the pistons then upgrade my cams to jhs stage 3 as the increased lift on the exhaust side will help with getting a new charge of clean air into the cylinder for my new pistons to work with. i think the busapistons are a good idea, but remember the busa isnt rated for very high rpm, nowhere near the gsxr1000/blades and not a patch on the new r1's so a purpose built piston may be better (thats my line of thinking anyway). the busa revs higher than the sv, but i tend to think the i4's rev higher anyway as they've got 3 other cylinders to share the load with so the force on each piston isnt quite as much. i think ill go with the jhs pistons, should be in about 2 moths time (gt some stuff to pay first) ill let you all know how i get on

trick

[northwind]

Cool, I'll be watching so you'd better do it :)

[trick]

no worries mate, ill keep you posted, ill try and get it dyno'd as well and post some power gains too

talk soon

trick

[davyf]

I have just gone from 700 back to 650 std pistons due to the increase compession it used to hammer the battery on starting. To be honest I can hardly notice the difference, suppose its because the bike was of the road over the winter. Oh I also left the cams in, the heads were ported, ignition advance, K&N jet kit, Race pipe. Had it Dynoed last year but the chain & sprockets were totaly shagged, the graph had a zig zag pattern still showed 75bhp could easily been a lot more if not for the chain.

[trick]

im going for a full after market x system, kNn, unprated oil/filter, high comp pistons, stage 3 cams new wires and plugs

trick

(p.s. already got m,ost of that its just the cams and pistons i need)