Puzzled with 1984 ATC 110. NEED HELP!

[benji7]

I recently received a Honda ATC 110 (1984). The previous owner had said it ran but has been sitting. It was getting spark and already came with a new carb. It wouldn't start even with starting fluid in the cylinder or through the carb. It appeared to have low compression so I figured something was wrong internally. Upon tear down the engine had already been rebuilt with a new piston head and rings along with the timing appeared to be correct. Should I replace all the gaskets and seals? Check the valves and cylinder head. Any help would be great thanks.

[ps2fixer]

First thing I would have done if I was in that situation is do a compression test so you have actual numbers to work with. Leak down test can inform you where the compression is being lost to (valve(s), head gasket, rings). Make sure the valves are adjusted correctly, the piston should be a a pretty snug fit in the bore, piston ring end gaps would be more involved to measure, but pretty critical to have right too. The actual valves could be leaking and need to be ground/lapped. I'm no engine builder, just some of the basics I'm aware of.

If you put it together to do a compression test, you can also put a little touch of oil in the cylinder and repeat the test to see how much the compression increases, if it's a lot then most likely rings are the source of the issue.

FYI, whenever you pull a head, unless it's a copper head gasket, you should be always replacing it as they are not reusable (some people get away with it, but it's not the proper way of working on them). Copper gaskets need annealed when reused as they harden when clamped and annealing makes them soft again to seal well.