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View Full Version : biggest engine ?


LT250RMan
02-18-2008, 11:51 PM
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 ?
quadbuilderJP
02-19-2008, 08:30 AM
KTM 520 maybe..& hell since you want displacement--- bore and stroke it!!
Nevada520
02-19-2008, 12:12 PM
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.
quadbuilderJP
02-19-2008, 12:16 PM
there you go-- isnt that air cooled too. No radiator to mount.
00.400ex#55
02-19-2008, 01:57 PM
cr500!

hell with the frame bracing and guseting it takes to hold that in you may aswell build a streetbike one.
LT250RMan
02-19-2008, 04:14 PM
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 ?
Nevada520
02-19-2008, 04:32 PM
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/
LT250RMan
02-19-2008, 05:01 PM
That looks crazy. I wonder if he had to do any modifications to the swingarm for sprocket alignment.
Nevada520
02-19-2008, 05:05 PM
http://www.exriders.com/vbb/showthread.php?s=&threadid=306712

check out his thread......I think he gives a few details about the frame mods and a few other things.
LT250RMan
02-19-2008, 05:45 PM
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.
TJ Bradley
02-19-2008, 08:28 PM
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.
Nevada520
02-20-2008, 10:33 AM
I've always heard that the 426 was the easiest to put in a 400EX frame. SS440EX might actually be making a few more.
LT250RMan
02-20-2008, 01:57 PM
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.
kodymx13
02-20-2008, 06:56 PM
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.
LT250RMan
02-21-2008, 11:49 PM
Does anyone know if JB racing still does the frame conversion for the CRF engine ?
1krazyquadridr
02-22-2008, 03:28 AM
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.