400ex bored .100 over?

[wicked400man]

hey guys, i just had my 400ex bored 1 over by my local dealer im in the process of putting her back together with a hotcams stage 1, just wondering if you guys think i will need to rejet? i have a full white bros e series and its jetted right for that.........also boring it 1 over do you guys have any clue what cc it will b at?

[MadMax27]

I doubt that will add any cc's. CC's are usually added by means of intake and exhaust boring-porting, and a longer crank that allows more downward piston travel. Bored 1 over ? Ive not heard of that, Oh well, as long as it works... It wouldnt hurt to re-jet. maybe next size bigger.... and bigger pilot, you should do a plug check, that will tell you if your in the right range.

[nosliw]

.040 over is a 406, .120 is a 426 and .080 is a 416 with a stock crankshaft.

so do the math your close to 420 :bandit:

[TC426EX]

who the hell makes a 420 piston?

[cals400ex]

when they said they bored it one over, they didn't mean 1 millimeter did they? 1mm = .040 over = 406

[wicked400man]

they said 1 over....but i got to thinking, its probly one mm i dont think they can bore .100 over and i doubt they make a piston for that....so i really dont know, ill check into it...

thanks alot guys, i really appreciate the fast replies and they helpful hints/comments

[400exrider707]

Originally posted by wicked400man
they said 1 over....but i got to thinking, its probly one mm i dont think they can bore .100 over and i doubt they make a piston for that....so i really dont know, ill check into it...

thanks alot guys, i really appreciate the fast replies and they helpful hints/comments

The stock cylinder can take a bore of .120 which is a 426, but its not recommended as the cylinder is paper thin. Chances are it was 1mm over. Didn't they give you the piston box with your stock piston back?

[wicked400man]

no they didnt, but i did call them and it is .100 over, how reliable do you think this will be? and with this much boring do you suggest a stage 1 or stage 2 hot cams camshaft

[chucked]

Originally posted by cals400ex
when they said they bored it one over, they didn't mean 1 millimeter did they? 1mm = .040 over = 406 This guy is one of the few non-idiots on this website

[400exrider707]

Originally posted by wicked400man
no they didnt, but i did call them and it is .100 over, how reliable do you think this will be? and with this much boring do you suggest a stage 1 or stage 2 hot cams camshaft

Personally I would go with a stage 1 being its only 11:1 compression, but you have to ask yourself which will suit YOU better!

[400exrider707]

Originally posted by chucked
This guy is one of the few non-idiots on this website

Kind of random, but I agree

[400exredrider]

if its .100 over youll have to have a special piston made:ermm: i bet they mean 1 size over which is .040 like cals said 406 i wouldent worry about the cam until you get the piston resolved, if it is at .100 over they are morons and youll will most likely have to be resleeved and re-bored... good luck