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XR 400 with an XR 650 motor

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Yes it can be done. Why couldn't it? FAB TIME!

Another questions is why would you want to? That is a better question.... But you can answer that by saying cause you want to.

I would advise against it as the 400 motor with a BB kit and other than stock carb rips! Even in stock form it runs great! I'd sudgest building the 400 motor. But to each their own, just dont cut up a perfectly good 400 frame if you dont have acess to a welder, tubing bender, grinder, protractor, drill, bunch of hand tools, a garage, lots of money, and a mind for fabricating.

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Well if that was the result then the guy would live and learn. But you would learn a ton on the way and have some experience under your belt to better choose componets for your next franken bike!

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650R or 650L?

Theres no way that you'd get a R motor in, because where are you gonna mount the radiators????

there may not be room enough i the 400 frame to accomodate one of the 600/650 engines

but for the rads? they are the smallest of your problems: weld or braize some mounts to the frame and bolt them on

I do not really understand your intention, Stoykkid

if you want the power or torque of the 650 why not ride a 650?

it will not be much lighter in a 400 roller, if you can fit it

so what do you want to achiev?

and let me twist your question and give it back:

can you watercool an XR250?

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there may not be room enough i the 400 frame to accomodate one of the 600/650 engines

but for the rads? they are the smallest of your problems: weld or braize some mounts to the frame and bolt them on

I do not really understand your intention, Stoykkid

if you want the power or torque of the 650 why not ride a 650?

it will not be much lighter in a 400 roller, if you can fit it

so what do you want to achiev?

and let me twist your question and give it back:

can you watercool an XR250?

I dont know where you are going with that question... but i'm interested to see how it plays out.

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You would want to reduce weight and increase power. You would be better off getting a crf250X motor and transplanting it. But again, why when the CRFx is so much better stock???

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A quick search shows the XR4 engine at 85lbs / XR650R engine at 88lbs (dry weight, add more for rads and coolant) / XR600 engine at 98lbs / 650L at 102lbs. The 650 motors are also a good bit wider than the 400.

I'd say do it!! Frankenbikes are awesome and it would be fun to do even if it's worse than what you started with. Gotta have some kind of winter project. :lol:

I'd say pop in a KTM300 2T.

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A quick search shows the XR4 engine at 85lbs / XR650R engine at 88lbs (dry weight, add more for rads and coolant) / XR600 engine at 98lbs / 650L at 102lbs. The 650 motors are also a good bit wider than the 400.

I'd say do it!! Frankenbikes are awesome and it would be fun to do even if it's worse than what you started with. Gotta have some kind of winter project. :lol:

I'd say pop in a KTM300 2T.

YEAH!!!! I'm with this guy!!! franken bike, franken bike, FRANKEN BIKE!!!!!!

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Hell,why screw around with just a little old 650.

Makes me want to ride a Tomahawk...

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I've seen an XR500 with a CB750 4 cylinder motor. (The XR750 logo on the swingarm was an awesome touch.)

Almost anything can be done, but why? It's not like the XR400 frame and suspension are a marvel.

A stock KTM 300EXC will lug like an XR400 and go rocket fast compared to an XR400.

If I had an 650 engine, I'd look for a 650 frame or rolling chasis.

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Almost anything can be done, but why?

to proove it can be done

the satisfaction of having done it

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It can be done, I think it would be to easy. Instead, lets try the 650r motor in a xr 200! And why your at it for the winter project I want to see a xr400 motor in a xr 100 frame, that will get the kids eyes popping out of there heads:cripple:

Can you picture a 650r with a xr100 engine in it for better gas mileage?

Edited by XL100allnightlong
adding

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