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amcgraw

XR650R motor into a CRF450 frame?

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So everybody wants to know about the elusive 600X. Another thread that mentioned a 650 hillclimber with a frame based on the geometry of the 450 got me thinking...

Has anyone checked if the 650R motor fits in the CRF450 frame? I haven't looked into this much, and it may be way off. If it fit, it could be a sweet bike: XR engine reliability, CRF suspension and frame geometry.

I didn't get any responses in the CRF fourm.

Thoughts?

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my 450's motor is pretty healthy now, but if it goes before i rebuild it, the 650 motor would definitely be considered...if it fits.

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the 650 motor by definition is a tall motor.

there is no way it will fit inside the 450R frame

the reason the 450 fits inside an essential 250 frame was becuase it is a screamer - wide bore means less stroke means less engine height.

the 650 is an old style chugger. meaning longer stroke taller motor.

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yeah forget it--lots of guys thought of that but its a no go.

the CRF600 will look VERY similar to a CRF450X. Slightly taller frame for the slightly taller head. The test bikes should be able to run 'CRF450x' stickers....thats how close they are likely to be.

I am guessing its got around 580 cc's-and a license plate.

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the 650 motor by definition is a tall motor.

there is no way it will fit inside the 450R frame

the reason the 450 fits inside an essential 250 frame was becuase it is a screamer - wide bore means less stroke means less engine height.

the 650 is an old style chugger. meaning longer stroke taller motor.

anything will fit with enough time, money, and effort.

The real question is; is it worth it?

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anything will fit with enough time, money, and effort.

The real question is; is it worth it?

well, it might be that 5 minute baja advantage that gets ya first instead of second or third......theres people out there that have the time and money to blow on it.....It would also be a much more agressive trail bike.

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Pneumatic variable timed valves (Honda has the patent on V-tec) would make the engine lighter and smaller(shorter).

EFI would also make the fit into the perim frame easier.

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With the amount of power and torque you can get from a stock bore 450 the amount of work require to jam a 650 in the CRF chassis just doesnt make sense.

Guys are getting a reliable and durable 60 HP with torque numbers in the high 40's ft lbs out of the stock bore 450.

And with the Athena 488 and and somebody elses 500+cc kit, the motors are lower RPM torque monsters making identical numbers to the 650 motor with a lot less wieght.

But those big cc CRF motors got some cubic dollars thrown at them too by the time you get the good parts to make them reliable.

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