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biggest engine ?
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Posted by: LT250RMan

I have a 400ex frame laying around, I was wondering what is the biggest engine I can put in the frame without cutting the top frame rails ?

Posted by: quadbuilderJP

KTM 520 maybe..& hell since you want displacement--- bore and stroke it!!

Posted by: Nevada520

Maybe the Honda 650......might be cheaper to get your hands on one. There are guys on here that have done both to the 400EX frame.

Posted by: quadbuilderJP

there you go-- isnt that air cooled too. No radiator to mount.

Posted by: 00.400ex#55

cr500!

hell with the frame bracing and guseting it takes to hold that in you may aswell build a streetbike one.

Posted by: LT250RMan

I want a liquid cooled engine but not a 2 stroke, I'm building a 250R right now for MX so I dont really want another 2 stroke quad. Will the XR650R liquid cooled fit ?

Posted by: Nevada520

Ping wunbadmp as he has one.......the attached link is from a thread he made about is a few days ago.

http://www.sandbros.us/v/sandbrosmembers/wunbadmp/

Posted by: LT250RMan

That looks crazy. I wonder if he had to do any modifications to the swingarm for sprocket alignment.

Posted by: Nevada520

http://www.exriders.com/vbb/showthr...threadid=306712

check out his thread......I think he gives a few details about the frame mods and a few other things.

Posted by: LT250RMan

Its sounds like the CRF450 conversion is alot easier to do. Maybe i'll just stick with the CRF engine and race that quad to.

Posted by: TJ Bradley

i have one with a KLR 650 motor in it. lol its bored and stroked. Its somewhere around a 700. =) It Hauls!!! Its a POS tho.

Posted by: Nevada520

I've always heard that the 426 was the easiest to put in a 400EX frame. SS440EX might actually be making a few more.

Posted by: LT250RMan

Ya thats what I head to but I don't really like yamaha to much i'm more of a honda guy. I know the CRF has more power and its a wet sump so I don't need to build a oil tank for it.

Posted by: kodymx13

man just go with a crf motor. their proven and even mildy build will walk away from todays 450s. ktm520s xr650s dont stand a chance. my mild motor eats them alive.

Posted by: LT250RMan

Does anyone know if JB racing still does the frame conversion for the CRF engine ?

Posted by: 1krazyquadridr

I talked to JB a few weeks ago, and they said they don't do too many of the conversions anymore, but they will still do them. Right now I think he said they've got a 6 week lead time though.