Probably the first thing to do would be adjust valve clearances.
Suzuki only use 0.001" to 0.003" clearance and tight or burned exhaust valves are a possibility.
Being 'shim over bucket' they were rarely adjusted at correct interval after first year or two.
It's a real good idea if you find any where bucket can't be rotated with cold engine to set things at least 0.001" larger than stock as it will close up within a few hundred miles. (don't go too large though as if you rev it too hard the shims can get 'spat out' and pretty much destroy head)
Seeing base circle of cam scuffed is also a dead givaway that clearances got too tight
Suzuki only use 0.001" to 0.003" clearance and tight or burned exhaust valves are a possibility.
Being 'shim over bucket' they were rarely adjusted at correct interval after first year or two.
It's a real good idea if you find any where bucket can't be rotated with cold engine to set things at least 0.001" larger than stock as it will close up within a few hundred miles. (don't go too large though as if you rev it too hard the shims can get 'spat out' and pretty much destroy head)
Seeing base circle of cam scuffed is also a dead givaway that clearances got too tight
