If what you're suggesting is simply raising/lowering the cam towers then that will do nothing for the valve angles and will present another reason for the infamous rubber sealing o ring pucks under the cam towers to leak. Also might move the cam lobes, which are bigger on these bikes, too close to the valve cover if raised. A stretched cam chain might handle this but a stretched cam chain should be replaced. Won't work bottom line.
i know the valve angles cannot be changed but the rocker's tangential force placed upon the head of the valve can be by shimming/decking the towers base. i don't know much about the puck leak, i didn't have any leakage on my F when i disassembled it. plus, decking shouldn't effect the bases figure. shimming might but that's what RTV is for
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we're just talking a few thousandths here. if the cam lobes are just a few thou from clearing the valve cover, i guess this wouldn't work or you could shave a little off the roof. plus, the more you shim/deck, the more you off-center the tappet from striking the valve (but then again, this is the basis behind my theory).
true, only way to have the cam chain comply is if it was stretched a little. new chain may not work but one with a couple thousand miles may. the tensioner should let loose some of the slack needed to raise the tower. if you were to deck, it's just the same is milling the head and again, tensioner takes up the slack. again, it's just a few thousandths of an inch we're talking here.
i'm just a little baffled why the exhuast wear out the most. you never hear about the intake guides. unless honda just canted the exhaust valves. if so this idea of mine may then mess up the intakes. hrm...