I owned one for ten years and when it died (bearing failure) I bought its big brother - Moki 2.10. (35 cc). They use low nitro fuel (either zero percent nitro or 5% nitro). I have success with OS "F" glow plug. Also I bought a Cline fuel system (about $50) that keeps the fuel pressure to the engine constant at all throttle settings and in any attitude. Very high power-to-weight ratio with the Moki glow engine.

They are made in Hungary I think. The US importer was Jim Gerrard for many years and he had the engines named "Moki". That ended about 8 or 10 years ago. Since then the factory has shipped some engines into the US labelled "Mark" engines. They are identical to the Moki's. Parts may be a problem.

Moki also makes some gasoline engines, but I have assumed that you are talking about the glow versions.

Mine usually starts on the first flip (backwards) after priming until wet. You flip the prop backwards and the engine pops and runs in the forward direction most every time.