88kx125 motor in 86 frame?

[lynde37avery]

so I'm restoring my first bike. it's a 1986 kx125. it currently has an 84 kx125 motor in it. it's got a cracked piece off the rear motor mount. so I gotta change it. but I got a lead on a 87 year motor. will it fit in the 1986 frame? with modified mounts I'm guessing? the frame is slightly different from what I see in pictures. any and all help is greatly appreciated.

[umberto]

The part numbers on the cases are close.  I know the 500 followed a pretty similar set up from 86-88, so I think it would work for the 125 as well.  They didn't go to the perimeter frame until 90 , so I can't imagine them changing anything on the cases just for a mild update of the bike.  Of course everything can be made to fit with a welder, light fabrication, and some time, but I think you should be good.

[lynde37avery]

thank you.  I'll find out here real soon if it all works in the frame.  and if I can't get a motor to run in it I will just retro fit a newer 125 into the chassis. internal parts seem to be few and far between

[lynde37avery]

nope it won't fit. exhaust port on the cylinder is different because the frame is different as well.  good enough.  wish I could post pics on this site to show progress.