HBTim wrote on 07/15/15 at 14:19:31:engine motor number is : P401112153
That's probably an '86
I thought those cut outs in the fin supports looked odd.
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Yup you'll want to swap the rotor if you use that engine.
Swapping the heads would be ok if the bottom end is still good.
There's a lot we don't know about '86's which is the 1st year of production, we haven't seen a whole lot of them.
I'd check every part number between the 2 years you plan on swapping for revisions.
The format is xxxxx-24B00 and a revision to that will be xxxxx-24B01
24B means it's designed for our bike