[Dreigh_Ban]

I've been looking around the internet for about 2 hours now and finally decided to ask here. i know that it is possible to swap the CRF250L's engine with relative ease with the CBR500R's, but i would rather swap my engine to the CRF450X's engine but have found nothing on that. if anyone could be of any assistance that would be greatly appreciated.

[JimDirt]

Welcome to the site !!

So you are wanting to put a CRF250L engine in a 450X frame ? , or a 450X engine in a 250L frame ?? if its the latter , i don't believe the 250L frame would handle the power , nor would the suspension work well with the extra weight

Not sure what your trying to accomplish with whatever swap it is your trying to do , a little more background info would help a lot , so you can be answered properly , you have not provided much info , so more detail would be very helpful .....

[Dreigh_Ban]

Welcome to the site !!

So you are wanting to put a CRF250L engine in a 450X frame ? , or a 450X engine in a 250L frame ?? if its the latter , i don't believe the 250L frame would handle the power , nor would the suspension work well with the extra weight

Not sure what your trying to accomplish with whatever swap it is your trying to do , a little more background info would help a lot , so you can be answered properly , you have not provided much info , so more detail would be very helpful .....

I would be trying to put the 450X engine in the CRF250L frame. if what you say is true then if the frame would be able to handle the power, then the suspension would be easy to fix. i do not believe that the forks would be an issue where power is a factor, never the less i am no mechanic and will need an opinion from another person who knows what they are talking about

[JimDirt]

The suspension would be weight issues , both front and rear since the 450X engine would obviously weigh more so stiffer springs and possibly stiffer valving to hold the bike up in the stroke , since if the bike is sagging any , then the suspension will not work properly as the forks and shock would be farther down in the stroke , and valving is somewhat position oriented , meaning certain parts of the valve stack are meant to be opened/closed during certain parts of the stroke to prevent harshness and handling issues , the farther down in the stroke the suspension starts out , the harsher the ride will be , and springs don't always cure the issue , when extra weight is added , because the springs only hold the bike up in the stroke , but do nothing for the speed the suspension actually moves up/down , that is controlled by the valving , so both play a part in handling , etc , follow ??

As far as the frame holding the engine , that is another thing completely , as the torque and weight of the larger engine , puts different stresses on the frame sections and welds than the original engine would , so its possible the frame would have to be gusseted in specific high stress or weak areas , that would have to be assessed by a structural engineer , its not something you just want to "hope" works , as a bad result could be deadly , especially if the frame came apart at any high speed , so its not something to just "guess" about , the 2 bikes frames would act very differently and must be addressed as such before just trying to plop the engine in and ride off , so take that into consideration before attempting any of this , remember , the time you spend researching before doing anything can not only save you from wasting money , but could also save your life , and i am nothing near a structural engineer , so i can not say , go ahead and swap and all will be well , personally , i think its a bad idea , and you would be better off just getting a 450X if that is the ultimate goal is to get the power/torque of the engine , as the weight will be close to the same once swapped , so you would not be gaining anything , and taking chances with the frame not being able to handle the stress of the swap either right away or over time .....

Hoped that helped answer some of your concerns ..... be safe , and , if you have more questions , i can try to answer them , but if they have to do with the structural integrity of the frame , that is beyond my knowledge maybe someone else can chime in that has more structural knowledge and give you more defined answers .... Jim

[Back2-2]

Jim's back !
Well stated and good recommendations.

There ya go Mr. Dreigh_Ban. Time to upgrade to whatever bike you need to do what it is you want to do.

[JimDirt]

Jim's back !
Well stated and good recommendations.

There ya go Mr. Dreigh_Ban. Time to upgrade to whatever bike you need to do what it is you want to do.

My post wasn't that long was it ??

[Dreigh_Ban]

The suspension would be weight issues , both front and rear since the 450X engine would obviously weigh more so stiffer springs and possibly stiffer valving to hold the bike up in the stroke , since if the bike is sagging any , then the suspension will not work properly as the forks and shock would be farther down in the stroke , and valving is somewhat position oriented , meaning certain parts of the valve stack are meant to be opened/closed during certain parts of the stroke to prevent harshness and handling issues , the farther down in the stroke the suspension starts out , the harsher the ride will be , and springs don't always cure the issue , when extra weight is added , because the springs only hold the bike up in the stroke , but do nothing for the speed the suspension actually moves up/down , that is controlled by the valving , so both play a part in handling , etc , follow ??

As far as the frame holding the engine , that is another thing completely , as the torque and weight of the larger engine , puts different stresses on the frame sections and welds than the original engine would , so its possible the frame would have to be gusseted in specific high stress or weak areas , that would have to be assessed by a structural engineer , its not something you just want to "hope" works , as a bad result could be deadly , especially if the frame came apart at any high speed , so its not something to just "guess" about , the 2 bikes frames would act very differently and must be addressed as such before just trying to plop the engine in and ride off , so take that into consideration before attempting any of this , remember , the time you spend researching before doing anything can not only save you from wasting money , but could also save your life , and i am nothing near a structural engineer , so i can not say , go ahead and swap and all will be well , personally , i think its a bad idea , and you would be better off just getting a 450X if that is the ultimate goal is to get the power/torque of the engine , as the weight will be close to the same once swapped , so you would not be gaining anything , and taking chances with the frame not being able to handle the stress of the swap either right away or over time .....

Hoped that helped answer some of your concerns ..... be safe , and , if you have more questions , i can try to answer them , but if they have to do with the structural integrity of the frame , that is beyond my knowledge maybe someone else can chime in that has more structural knowledge and give you more defined answers .... Jim

This helped alot thank you. And I don't believe that it was too long of a post at all. I'd rather read an essay to be well informed than a 3 sentence response that had little information

[Aussiecrf230]

Jim is your man for an essay, but it is all useful info.