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Crf250r frame with 250x engine?

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Hi guys I don't know if this has already been covered on here but my engine is complete toast I've got a crf250r 2008 but a cheap engine had popped up local only difference is it' the crf250x 

So the big question is would the crf250x mount into the r frame without issues and is there any differece in power 

I know the x has electric start so would there be any additional running gear needed to get the engine running in my frame thanks people 

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Can't confirm but thinking as far an engine mounts go

a 250X engine should be compatible up to a 2009 model year R chassis.


The CRF250X engine is 'de-tuned' for trail and off-roading versus the motocross version.


-smaller lift and duration cam

-smaller bore carburetor (early 250R's also had a 37mm versus 40mm), leaner settings

-heavier flywheel with lighting magneto

-wide ratio gearbox

-some model year X have a 'PAIR' air valve for emission purposes, if so you'd have to install a block off kit.


It also has a electric starter, the battery mounts in an X specific subframe under the seat just above the air filter. 

You access the air filter on a 250X rather by a side panel in the left side number plate.


To avoid possible headaches you would ideally also require the X wiring harness to run the engine,

which unfortunately would also require some alterations as the 250X has a headlight & taillight, starter relay, button, clutch switch etc.


For trail and off-roading this swap is certainly a consideration but, if you rather ride motocross tracks

the wide-ratio gearbox and engine's low to midrange power characteristics are far from ideal versus an R.


Edited by mlatour
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Well that answered my question and more it just isn' worth it I suppose and yes I ride tracks so I understand what your saying power wise wouldn't be much good at all thanks for the reply and all your information it' greatly appreciated 

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