The ATC 90 engine work continued today, focusing on the head. I took the carbon-caked valves to the wire wheel, which made easy work of removing the carbon. While the exhaust valve looked good, the intake valve face was too worn to be used again. A new pair of valves was available online for under $20, so I opted to order them instead of reusing the original pair.
A tiny wire wheel mounted to a rotary tool took care of the carbon removal from the combustion chamber. Gasket mating surfaces were cleaned too. The original exhaust pipe and muffler were long overdue for replacement. A hole in the bottom of the muffler was visible next to an old “temporary” patch. The original exhaust parts will be discarded since the aftermarket exhaust arrived last week.
Once the new valves arrive I will continue to reassemble the engine. Until then, I’ll clean and re-lubricate the chain and throttle cable. I’d like to see the ATC 90 back in good running condition before the snow flies.
Intake valve face is too worn to use 
Rotary tool cleans carbon 
The holey muffler will be discarded 
Combustion chamber is cleaned 
New exhaust is test-fitted
