It looks to me like the exhaust valve seat come loose in the head casting... so the previous owner staked it down with a flat-bladed screwdriver and hammer... so he/she could sell the bike for more than its worth. It could also be a screw that come loose and got ingested... but thats a long shot with gazillion:1 odds, cause I see where the flat-blade staking job dinged the valve seat inline with a stake. The person who did it was careless.
Regardless of what happened its a heavy oil burner and needs a complete top end rebuild, minimum. Good news is, you may be able to rebuild it for $600 or so...? Hope so, those old 300s may be the best bike Honda ever made...
Regardless of what happened its a heavy oil burner and needs a complete top end rebuild, minimum. Good news is, you may be able to rebuild it for $600 or so...? Hope so, those old 300s may be the best bike Honda ever made...
