440 bore questions...

[chris_bchs2007]

okay, so i just got an 03 400ex, the kid told me it had a blown head gasket, but he didnt know anything about engines, and turns out it was pretty much the whole top end... so im gonna go ahead and bore it to a 440... im not gonna cam it or anything... and other than a pipe, jetted and K&N filter that im gonna replace with a uni, the bike is pretty much stock... will the bike be able to handle the kit? and i dont really understand much about the compression with the pistons, so what compression would be easier on the stock bike? i know i need to get heavy duty studs... just dome additional info that may make it easier to help me out: im 18..a bigger guy, about 6'2 260 but im decently athletic... i dont jump much, and when i get enough balls to do it, its not much air, 5 or 6 feet at the most... i live in SE Kentucky, so i ride trails... i just want to be able to spank all my friends on their stock 400ex's without having let to let one of my skinnier friends ride my bike lol... i dont know much about engines so sorry if this is a dumb question but any help would be greatly appreciated... also, other that some scoops, do i need to find a better way to cool the engine... thanks guys

[hypersnyper6947]

go with the 11:1 compression piston, you can get a wiseco kit on ebay for not to expensive, if you are already going to have it all apart i would go ahead and do the cam (stage 2) , its only 140 bucks on ebay shipped.

[chris_bchs2007]

thanks, i really appreciate the help...

[drew416ex]

Also you cant bore to a 440, you have to get a oversized sleeve and get it bored to size.

[madmartin]

hypers right with the top end. if it's apart do it right. the cam is worth the cost, the head studs are right on, and throw in a heavy duty timing chain. my stock chain stretched, jumped timing and wiped out my top end. The chains cheap anyway. I use the 12.5:1 piston but when i rebuild it gonna drop to the 11:1. As for cooling i don't use anything but scoops are cheap though and can't hurt.

[chris_bchs2007]

the bore kit im getting comes with a sleeve, and i know about getting the cylinder bored, thanks for looking out... i read about getting a heavy duty timing chain and ill prolly go ahead and get it too... thanks for all the help guys