Just finished up a top-end rebuild on a 90cc Manco I bought off a guy, non-running. Original piston and rings were shot. Put it all together today and, after some carb mixture tweaking, got it running what seemed to be pretty well.

Took it out back to see if the clutch would engage properly, it made it about ten feet and lost power (didn't seem to have much off the line). Basically, it seemed to bog down if I put too much gas to it.

After that, I rolled it back into the garage and kicked it back on. It idled decently, but kept dying. Eventually it wouldn't start at all.
I've been fiddling with the carbs, since it seems like that might be the issue, but I'm also concerned that oil might not be getting from the tank to the cylinder (though it should be-- I just don't trust oil tanks)... can I pre-mix for these atvs?

Not sure what to do next.
Ideas?

 

The adjustment screw on a 2 strokes carb meters air.. its a air screw.. on a 4 stroke it meters fuel.. So turning out a fuel screw on a 2 stroke adds fuel.. on a 4 stroke it adds air.. Id turn the mixture screw in until it bottoms out(softly) and turn it out a turn.. fire it up and get it armed up if you can.. if its bogging turn the screw in.. if its gasping for fuel turn it out.. 1/4 of a turn at a time..

Yes you can remove the oil injection and run premix.. You need to remove the pump and all the oil lines and plug the holes in the cases the oil lines were in..

 

I didn't see where you bored the cylinder to the piston which makes me think that you didn't a get bigger piston.
So I'm wondering if the bore was wore and the new piston isn't producing enough compression.

 

I tell ya I just put a harbor freight 212cc in my Manco it is now a wheelie machine just stopping isn't really gonna happen