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,,,, :D :D :D

[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,,, :D :D :D :D

[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/showthread.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.

[3leggeddog]

well i got the swingarm bolt cut out today,darn thing was seized in there of course.after getting the motor to sit where it should and talking somethings over with derrick i relized it won't be to bad.gotta make a new custom exhaust flange,some motor mounts and buy a blaster kicker.hopefully it will be worth it.the motor looks beefy sittin in the frame,the p.v. setup makes it look huge.i'll post some pics as soon as we get to weldin,and stuff is more permanent.

does anyone know if the cr and 250r head are the same.they look interchangable,but i'm not certain?

[hrc85250r]

nope, unless its a certain year...i cant remember the year...but i think its only a couple certain ones....

[3leggeddog]

it's a 91 cr motor if that helps.they are shaped the same but the internal water jackets are a little diffrent.

[PLJ.]

I would really like you to finnish this project and get all the bugs out of it, because I have been thinking about building one for years!! It would take most of the bugs out of it!! Seriously, back in the early 90's there were two 88 TRX250R's that came every year to the Ice Nationals. The bikes and riders were from out East somewhere, New York or Mass. Anyhow, they both had 86-87 CR250R HPP motors in them and they literally FLEW!! These were the days of 250R Chuck E, CT, and Trinity ported cylinders, no one was running any big bore stuff then, and nothing could touch these CR motored quads!! Good luck.

[3leggeddog]

i hope to have the same results.i hope it rips.my freind that runs the local shop said if it works it will be un godly fast.i'll keep this post updated and we'll see how it turns out.

[PWK39]

are you using the stock rear motor mount? I wan't to do the same thing as you but on mine it looks like the swingarm bolt will go straight through the rear mounting ear on the motor.That is the way it is on the cr250 no mount just the bolt through the motor.the whole motor seems to sit back more this way.

[3leggeddog]

yeah thats the way i'm going.also you will have to cut off the lower motor mount on the frame,so the motor will drop down.otherwise the exhaust port will hit the front of the frame,and the pipe won't fit.you will need to fabricate a custom exhaust flange also,this way the pipe can connect at the proper angle,and seal.i also think the head mount will have to be modified.right now the head hits the mount on the frame,but if i cut the mount on the frame in half,(between the two bolt holes)this will allow me to use some flat stock steel to make a mounting bracket for the head.i know it's hard to follow but i'll get some pics up.man i hope it makes some power cause i'm cuttin up an 86 frame for this swap.no major mods,it's all stuff that can be welded back on,and not seen at first glance.

[Derrick Adams]

I can tell you this engine will be in the bike and all the fab work done by the end of the week. We have 3 frames to paint next week and that's one of them!

[3leggeddog]

way to get me motivated D. DO IT,DO IT NOW!!!!!!!!!!!!!!

i'll be happy to have it mocked up and share the info with you pwk39.

[PWK39]

Thanks for the info 3LEG . My frame is an 85 though might some small differences. any information you have is helpful i am not as far along as you so I'll be up against the same obstacles as you later on.

[Louis Mielke]

Forget the blaster kicker. Go to Servic Honda and beat them up for one of their reverse kickers they're using on there 2005 TRX250R. That would make it perfect. No shorty kicker or cut fenders neccessary.

[Red Rider]

That's good advice LM. That's what I'd attempt to do, if I was going to go the "entire engine swap route."

[3leggeddog]

cool,thanks for the advice.i was un aware they had a kicker like that.

we got the motor mounted up at this point.all thats left is sproket align ment,and some plumbing.pics soon!!!!!!