I've got an 86 with 24K that hasn't run, and sat outside for 2 years or so. ITs rusty, and the cases are really flaky white.  gross looking.  The bike is ugly, so I dont' feel too bad attacking it with my HS kids.

I happen to have a 2002 engine bottom end in GREAT shape (8K miles?)
the top end and piston are gone....it was "holed' somehow.

Question:  to get a lower mileage bottom end, should I move my top end over???  any problems with the interchange of parts?

Also:  I torn about a stock redo, or a cafe bike.  This is a LOW budget build for sure.  any opinions on what to do?

I've already sent an email to the cam tensioner guru.....gotta get one either way!

uh oh.  I have a complete 86, and the bottom end from the 02(?).

will the 02 bottom work with my 86 ignition box?

And since you say the piston was holed... gonna have to make sure you get all the pieces out.

You can swap the covers instead.  This would also give you the benefit of the improved starter gears on the '86.  clutch cover is a direct swap as far as I know.

Cam chain problem is the usually method of holing a piston.