big engine into TRX250R swap

[ponybetter]

Hi everyone,
I have an '87 TRX250R that I am thinking of swapping a larger engine into. Does anyone know of an easy swap?? I know I can punch out a 250 motor, but I worry about reliability. I hear a CR500 only works with proper counterbalance to reduce vibration, but don't know how to pursue that. I am thinking 4 stroke street bike motors, but would be having to fab a bunch of stuff to get it to fit.
Any help is appreciated. Looking forward to being part of this forum; I have looked through it quite a bit and it has a lot of good advise on it.
Thanks,
Brian

[suzuki LT250R]

I say go with the CR500 motor. That is what I plan to do with the 86 LT frame that I have. They might vibrate alot but look at how much motor you have.

[bansheeracer18]

my buddy put a lt500r in one it goes it gust as good as the origanle but more power and faster

[Banshee]

I would keep the 250 the way it is buy a rolling chassis LT250 and put a 500 motor in it. What makes the 250R so great is its size and weight. Also it just handles like a dream. I would be afraid swapping a different motor in there would just kill all of those things. If you just want something that goes fast in a straight line I think there are better options out there.

[terboed]

heres my stalled project.

trx 250r with a 2002 cbr f4i motor in it.

i would say stick with the 500 idea, there is alot more fabing involved than one would think when stuffing a 4 cylinder street bike motor in a quad. mine is for sale if you want to finish it. i have all the parts to bike run.

[ponybetter]

Thanks for the input. That project looks great! How complete is it and how much are you trying to get out of it? do you have any further pictures? I realize it's all black (which looks great), but there is no definition between components in these photos. That is what I was thinking on doing, but with the long swingarm, this is mainly for hills and mild duning. You wouldn't want to go catching too much air for fear of bending or breaking that swingarm (or have you figured out a way to overcome that?)

Where are you located? did you have to cut up and modify the frame very extensively, or is the fabbing mostly bracketry?

Look forward to feedback.

Thanks,
-Brian

[terboed]

check out the other pics in the classifides section under -250r/cbr hybrid unfinshed project for sale- the frame had to be cut and new steel bent to allow room for the motor to physicly fit and so the chain would align properly. i would sell you the bike for $2500 (thats what you see in the pics and three boxes full of parts), but thats as low as i would go befor parting it out. im in portland oregon. i think i have a few more pics earlyer on in the build if you want to see them. as for the swing arm bending or breaking, this thing is ultra ridged. it was built by MP Racing and they have duned hardcore on these arms for years and not have one brake (thats why i had them build it). the swing arm alone was $450, the motor $1350 and you know where it goes from there. im in it a good amout of cash, but would rather sell it as a whole than part it out.

[ponybetter]

I can't figure out how to get to the classified section. Can you point me there?

[ponybetter]

Found it. Nevermind.