[scherry945]

Does anyone have experience swapping a 1987 XR100R motor into a 2003 XR80R frame? Curious if it bolts right up so I can modernize this thing. Thanks

 

[dirtbkr188]

Looking at microfiche diagrams for both models, they seem to use the same engine mount bolts and brackets, and use the same swingarm bolt, as well. Only one way to find out for sure, and that's to pull the engine and try it in the 80 frame.

I do know that you can use a 100 top end on an 80 lower end, so the frame clearance with the valve cover should be the same.

 

[scherry945]

Looking at microfiche diagrams for both models, they seem to use the same engine mount bolts and brackets, and use the same swingarm bolt, as well. Only one way to find out for sure, and that's to pull the engine and try it in the 80 frame.

I do know that you can use a 100 top end on an 80 lower end, so the frame clearance with the valve cover should be the same.

Hey thanks there, yessir it bolts right up and fits well. I'll post pics at some point. Tough part is now the ignition. The coil and brackets aren't the same and ots all different. 1987 (top right in the pic below) doesn't have a CDI, I guess?

I wonder if I can put a 2003 coil and CDI on a 1987 motor? Would I need to upgrade the stator and flywheel?

The 1987 coil/condensor/noise suppress aren't in great shape so I may upgrade to fit the new frame, if I can.

 

[dirtbkr188]

The '87 XR100 engine is a contact points/condensor engine, you would have to upgrade to a '92 and newer stator, flywheel, and CDI-type wiring harness. There is a way that you can use the newer flywheel on the '87 crank. The newer flywheel has a bit wider groove for the crank keyway, but you can't just swap in the newer keyway, it doesn't fit in the older crank slot.

I can't remember the product name, but applying a couple of coats of it to the 3mm ('87) keyway will let you use the newer 4mm-slotted flywheel, to take up the 1mm width difference.

 

[scherry945]

Thanks for the insight, much appreciated