Xr650 engine in a cr250 frame

[searcher415]

Posted this over on supermoto junkie but i thought this would be a more appropriate area. I know it's not a cr500 engine going in the frame but same concept applies.

How much bigger is an xr650 engine then a cr500 engine? Think the frame can be modified to take with out sacrificing strength? This would be going into a super single. Nothing that's going to get beaten off road. I've always wanted to build one and i want to keep the chassis as light as possible.

[Roostius_Maximus]

a crf450 gen3 frame would have the most room

[AlisoBob]

Thats a awefully big motor.... Jays has a external oil tank too ( it uses the frame)

Theres allot to think about with this one...

[searcher415]

Thanks, my only concern is the width. It's an 04 650.

[searcher415]

An external oil tank is going to be an issue. I could always try to modify the upper frame rail. Gas tank will be another problem though.

[supermotoflunkie]

you will have tons of roomm above the frame for gas tank. Those SS use sport ike looking faux tanks. I.e. A cover

[searcher415]

That would be best case. I could probably save weight versus a custom build aluminum tank using a plastic one with a cover.

[dubious01]

XR's only at one time sold an aluminum oil resevoir kit for the 450 , and added 1l more capacity, since the 450 would blow its oil out the vent all day desert racing. They placed it between the lower frame rails under the motor, with a skid plate as additional protection.

Not sure if they still sell something like that, but worth checking maybe.

http://www.xrsonly.com/content/

[100hp honda]

find a damn good welder. dont want that boat anchor falling out

[87CR500Rider]

That's a 4 stroke I'd ride.

[searcher415]

find a damn good welder. dont want that boat anchor falling out

Haha, yeah that would be painful.

They placed it between the lower frame rails under the motor, with a skid plate as additional protection.

Great idea. I'll make one. It will get hidden by the fairings anyways. Purchased the engine. Now i'll i need is electric, carb, frame, ect. Basically everything.

[gregrobo]

[matt_NC]

I can't remember where, but I read an article once about an Engineering grad student who built a super single around an XR650 motor. He designed his own frame.

There was a ton of pictures. Those motors are huge!!!!

[searcher415]

It's going to be awhile before pictures. I'm a full time engineering student right now.... That's my biggest concern is how i'm going to get the engine in and out of the frame if it's even a possibility. May just have to modify the frame to accept it and then assemble it after it's mounted.

[AngryShawn]

Sounds like a hell of a lot of work for what is probably minimal return. Why not just make the XRR into a supersingle and skip all the headache?

[AlisoBob]

I was lookin' at soliD bro'S XR650 tonight.

If you think that motor is fitting in a 250 2 stroke frame, your high as a kite.

[kball1313]

Yeah man, anything's possible, but it's tall, wide and heavy. I loved my 650R, but I think you'd be better to focus on a different build. But i'll keep watching if you take the plunge.

["SOLID Bro!!"]

I wouldn't put my xr650r engine in anything. It's a tank. leave it in what it's in, your not going to gain anything, unless your talking about a steel frame xr650L That's why My 500 will be done soon. I'm old tired and fat and want something not so heavy.

[searcher415]

I was lookin' at soliD bro'S XR650 tonight.

If you think that motor is fitting in a 250 2 stroke frame, your high as a kite.

I'll probably have to buy an xr650r frame then. I just want a supersingle as a reliable light weight commuter bike. I want a winter project too so i don't mind the work. I've never taken the time to really look at the size of a 650 i guess i'll be in for a surprise.

[AlisoBob]

Buy a KTM

[AlisoBob]

Now you've seen one.

["SOLID Bro!!"]

I don't think you actually save that much weight by changing frames. It's already Aluminum, on mine I swapped to a 450 front suspension and it works better but no weight savings. I think most of your weight savings is in the fuel capacity. maybe +-5% in frame weight.

[nmdesertrider]

Ive got one and by far it is the biggest dirt bike engine i have ever seen. I'll put some pics up when I finish with the lights and tank.

You can buy them super cheap- I will be running some hi speed races on it next year.

[kball1313]

Just lace some 17's on it and you have a killer reliable motard. I rode mine for a few years and put a ton of miles on it. Gas, oil change, repeat. Stone reliable engine, just uncorked it.

[kball1313]

Just lace some 17's on it and you have a killer reliable motard. I rode mine for a few years and put a ton of miles on it. Gas, oil change, repeat. Stone reliable engine, just uncorked it.