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Motor swap do able or is it just a dumb dream

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Hey guys I'm thinking bout doin a swap with my yz,s I've got an old Frankenstein bike that was once a four stroke bike and someone married in an old yz free air motor then it soon poped and I seen a rebuild motor online so I bough it and fit it into the frame it worked ok but vibrated a bit so anyway the motor is I fact a 1999 yz250 I also own a 1999 yz125 , the 125 needs a top end now and I started thinking what a crazy project this would be so I am now to the point that I think it will work except the frt motor mounts need to be relocated a bit higher on the frame which wouldnt be a problem but I thought maybe asking if anyones don't it successfully before digging into it to far would be kinda neat to put the 99250 motor in the 99 125 or is this a unrealistic project

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If it is anything like the kx125/kx250 of the same era then the 250 engine will not fit in the frame because the engine cradle is different and swoops up earlier on the 125

 

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Well without cutting the frt mounts so far it looks like if I cut them then retrofit the motor and weld them back I place a touch higher but maybe I'm wrong anyone else able to chime in thanx a lot guys I love this site

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Like kxrob alluded to, the frame rails underneath the engine curve upwards differently between the YZ125 & 250. Do a Yahoo search for images of the different bikes and look at side views. No way for a 250 motor to fit in a 125 frame without cutting and welding key structural members.

Edited by CaptDan
withOUT

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Well not to say your wrong at all but I have the motor nearly sitting in the cradle it just needs to slide over a wee bit and down it just seems like the 2 frt motor mounts if they were relocated it would work but however I will prob take ur advice and not attempt it ,would be an awesome project though would be one of a kind

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