426 build question

[kiesta00]

My friend has a 2000 400ex with 39mm FCR carb and curtis sparks x-6 pipe. He wants to bore it to a 426...what all parts would he need for a reliable setup? We're looking at a JE 88mm 13:1 compression piston, hotcams stage 2 cam...what other necessary parts would he need to complete the build? like cam chain , head studs, gaskets? What would be the minimum octane to run a 13:1 compression piston? or would he be better off with an 87mm with 12:1 ? thanks

[atvracer980]

Remember- the higher compression, the more fatigue you will be putting on your connecting rod. I would honestly buy the 440 big bore kit, use the sleeve from the kit- find a 87mm piston and have the sleeve bored to that piston- this way your not sacrificing reliability by thinning out the stock sleeve and you always have the 440 piston for further bores. I would stay around the 12:1 piston, just to save about $600-700.00 for a rod replacement and use 94 octane or greater for your gas. I buy 2.5 gals of 108 and 2.5 gals of standard pump gas -it'll equal out to be around 95-96 octane and wont break the bank.

[kiesta00]

so an 87 mm with 12:1 compression would be less stressful on the rod? He doesnt want to have to put a new sleeve in the engine, otherwise he'd go straight 440 with it. would the 11:1 and 12:1 compression make that much difference in horsepower or not really?? thanks again

[sauch]

a banshee is the best bike and will always be the best, **** a 4-stroke hands down *****

[QuadJunkies]

Originally posted by sauch
a banshee is the best bike and will always be the best, **** a 4-stroke hands down *****
WOW.. Another intelligent one ... :rolleyes:

hope your 2nd post is more hlepful than this one was or you wont last long on this website.

[Colby@C&DRacing]

I agree with the sleeve and the 88mm piston 12:1 compression on a stock 400ex rod is pushing it. Will it work? yes How long? who knows