cr 250 powervalve swap for a 86 250r????

[3leggeddog]

not sure if this has been done before but i recently picked up a 91 cr 250 motor and a 86 r roller.i'm going to attempt to put the cr motor in the 250r frame.has anyone done this,and if so can you send me some info on what was envolved.i don't know that this will work,but with a welder and some torches i guess anything possible.i won't hack this thing up,noly make minor modifications.it seems that it will go,but the exhaust port is more forward in the frame so i may have to customize a pipe.the rear and lower motor mounts are the same and only the head mount,and front motor mounts will have to be fabricated.if it's too much trouble the motor will go up for sale,and i'll settle for a big bore motor.do you guys think it will be a very benifical swap?wish me luck and any input would be helpful.

[hrc85250r]

dude, just make mounts similar to the stock ones for the CR motor, run a k&n filter off the carb and jet it, you might need to get a custom pipe made, but if you can cut and weld decently you can def. make the CR pipe work easily....thats it!

[Tubsy]

Isnt the 250r engine better than the CR 250 engine?

[3leggeddog]

making the motor fit is not a problem,it's the pipe and getting the sprockets lined up that cause the difficulty.i want to use my paul turner high rev on it but there is no way i will cut that up.i never thought about a cr pipe.i got 2 stock 250r pipes laying around,one of those may go under the knife.

[3leggeddog]

the cr motor is powervavle so it makes more power,as far as the tranny and stuff i don't know which is better.just something different.

[NOS_350X]

Isnt the 250r engine better than the CR 250 engine?

Not even close that CR is better in every way you could possibly think.
They detune the quad/atc engines. The bike will be much more powerfull.

[hrc85250r]

cr puts out quite a bit more power, and it hits harder....and the sprockets will line up quite easily, just take your time jigging the motor up in the frame and put a chain up both the engine sprocket and the rear sprocket, look straight down the chain to see if it is crooked or has any alignment problems and adjust the motor bit by bit to get it perfect....if you take your time it will be perfect, ive done it many times, and i have NEVER thrown a chain...not even once...

[KASEY]

better think twice ,,, the atc frame is wider so your kicker won't clear the brake pedal,,, your going to loose a gear,, so it won't be as fast on top speed ,,, atc trans is a wide ratio 6 speed cr is a close ratio 5 speed,,, AND i doubt if you can just throw a pipe together that will do much for performance either,,,,

[hrc85250r]

well, i dont think the kicker would affect the brake lever, if it does you can fix it one way or another...and you can extend the "header" area of the pipe before the expansion chamber a few inches without affecting performance, also you can cut and spin sections of the pipe too...

if you dont want to do the swap...i will buy the motor from you!

[max]

i told you they have adapters for the pipe to go from the cr manifold to your atc head pipe!!!! so that aint an issh

[KASEY]

well, i dont think the kicker would affect the brake lever,

ok,, just remember i have a cr engine in a atc frame,,,

[hrc85250r]

lol, then why dont you tell him how to do it.!!! i only transplant big bike motors, never done a 250....ive only disassembled a mojave/kx250 cob job...

[3leggeddog]

well the issue with the sprockets not lineing up is a bit more severe then just sliding it a little.it's a inch or so,if i move the motor to where the sprockets line up the exhaust port is going to hit the frame.

as far as the pipe it will have to be an inch and half shorter coming off the jug.the problem lies with the pipe hitting the front tire.i don't think that is a real big deal.and max hooked me up with info on the adapter.

kasey,did you have problems with the sprockets lineing up?how did you resolve it?what did you do about the kick starter? and do you think the swap is worth the time and hassle.i just want something that rips,and isn't the same old 310 big bore.i would like something different.so has this already been done?

i'm gonna give it a shot and see how far i can get with out getting frustrated and selling this motor.thanks for your help and all your input guys.


i'm always open for offers,shoot me a p.m. with some numders if you want to buy the motor.it's all there,harness,coil,radiators.

[Power_Ram100]

I have a 88-91? Honda CR 250 motor in my 85 Tri-Z. It bolted right up the rear swing arm and 2 other motor mounts needed to be fabed up.

http://www.3wheelerworldforums.com/s...ad.php?t=32263

[3leggeddog]

thats a little diffrent then the motor i got.looks good in there,i bet it really made that yamaha fast,lol.