RE: Self taught flying - My diary / progress
G'day again Carl
I had the Magnum GP 40 like the one you have many years ago. I did not have any real problems with it but it never idled all that well. It was always a bit too rich at idle. It did not dead stick though.
If you want a really simple, reliable, easy to get along with engine which will handle some crashes and not cost the earth then the OS LA 46 is one of my favourite engines for trainers. It is not as powerful as the AX 46 or any of the other ball bearing engines with twin needle carbys but it is powerful enough for a trainer and tough in a crash.
Like your Magnum, it has no ball bearings but its crankshaft is supported on a bronze bush. It too has an air bleed carby but it is a good one. Here they cost about A$115.
The other good trainer engine is the Thunder Tiger GP 46. It is very similar to your Magnum but is made in Taiwan and not China. They are extremely well made, cost about the same as the OS and very quiet in the air on an 11x 6 prop (same prop that the OS LA 46 needs).
Both need fuel with some (and preferably all) castor oil and about 5 to 10% nitro. Any more is just wasting money.
I recently bought an OS LA46 as an experiment (to put my money where my mouth was). I took it out of the box. Put the needle valve in, closed it fully (gently!) then opened it about two full turns, fueled it, dropped a few drops down the carby, gave it a few flicks to get the fuel moving, applied the glow starter and flicked. It fired but did not run. Primed a few more drops and tried again but this time with the starter. She started. She was running a bit rich but would run at full throttle and idle after five minutes running. So I put it in a plane and flew it. It has never deadsticked and is now tuned a little leaner and runs perfectly. You can't ask much more than that for a beginner's engine.
Cheers
Mike in Oz