Two stroke Tech question

[Bob Purton]

As smallish two stroke motor with disc valve. The motor will only run with full revs range when on choke. Runs in the higher rev band without choke but not lower or idle. Whats your diagnosis? My guess is idle jet passage in carb blocked or hardened crankseals. Any other ideas?

[Big Al]

Sounds like blocked jet. Hard seals is an air leak or oil leak. If air leak then the mix is weakened. If oil leak you can normally smell it in the exhaust as engine oil smells differently to 2 stroke when not burned completely. Crudded ports/exhaust might be considered. Not up on disc valves.