Well this is what I have done so far.
Fresh bore to 68.50mm one of the previous owners had a sleeve installed.
I cleaned up the exhaust port and matched the sleeve to ports that I could reach, raised exhaust port 1mm and widened it 2mm.
Intake side I matched the ports to sleeve and opened up the lower intake ports quite a bit
Smoothed everything out also, not polished though.
I couldn't get tho transfer port openings cause all my porting stuff is for automotive app.
I have a carb on the way from a 91 KX500 PWK 39mm or 39.5 it's not here yet.
I could use some jetting advice if anyone has ran a bigger carb on one.
The stock pipe has a few small dents but otherwise in decent shape, probably gonna use air pressure and heat to remove the dents.
Any known tricks for the stock silencer? Mine the guy attempted to repack it but it all blew apart.
I think with a next size up tap and some new screws and thread lock it should work again.
What's a good set of reads for my app? Mine have a chip and hang open all the time, they look like a dual stage set.... Boysen? Idk
Foxx let me know what shipping is, I would like to see the difference between the pipes.