what 400ex kits

[JDiablo]

ok fellers....thinking on some engine work here....dun want to go to narly just a lil bit,bore it out a bit,and a piston,i have to run pump gas whihc i can get i think 93...so wat compression piston?10.5:1?and 416,440?ill do cam,piston,valves,rocker arms,ported and polished head fcr 41 mm carb...or you think that is to big and go with the 39>

[REAPER]

I happen to really enjoy my engine for trails and woods. I put an 88.5mm J.E. piston, 11:1 compression {this is as high as you want to go on pump fuel}, port and polish, cam, c.d.i., and clutch. Beleive it or not at first I wasnt really impressed but after a few rides this thing really started pulling hard from any rpm and any gear. I had the same frame of mind as you when you said you didn't want to overdue it and this is what I thought would be the most reliable set-up to where you don't have to tear things down all the time. Although they say it's a 440kit, it really is only like a true 433.something kit. My next step is to get a stroke job along with valves and springs. oh and by the way, make sure the engine builder is top notch, for this will truly make it or break it as far as TOP PERFORMANCE for your application. Good luck, Reaper

[ghak99]

I recently worked on and put back together my buddies 440. When he first got it I was only mildly impressed with it, but after I replaced the blown head gasket and cam chain and jetted it correctly, I am very impressed. It will start pulling hard from any rpm in any gear. It has some mild porting, a cam, 11:1 89mm piston, rev box, and the stock carb with an fmf slip on. It still seems like something is holding it back a little, but I can't talk him into buying a FCR and X6 just yet.

It looks as though you are going to do everything at once, so I would say why not go 440, and you might think about going with a heavy duty rod just to make sure it can take it.

[JDiablo]

maybe 440 kit with +5 mm crank?:macho

[REAPER]

maybe 440 kit with +5 mm crank?


Depending on which 440 kit and stroked like that, woohoo, your talkin prolly 460-465 territory. Hell yeah!!!:macho Reaper

[JDiablo]

o hell ye that sounds pretty rad...as long as i stay under 11:1 compression i should be narly on pump gas right?

[K_Fulk]

Originally posted by 300exrida
maybe 440 kit with +5 mm crank?:macho

Why stop there. Go up to a 91, 92 mm piston while your at it.

[JDiablo]

so wat will a 92 mm piston wiht a +5 crank give me?like close to 500?:confused: not to narly when it comes to bore size,x piston mm suttin or another,lol

[ghak99]

If I did my math right it would be a 499cc motor!

[K_Fulk]

I think you would be a hair over.

If your gonna end up getting a heavy duty rod. You might as well stroke it while your at it.

[JDiablo]

maybe i don't want to go to crazy might by a used motor,imma end up dropping the crf bomb on it soon neway:o