jaka

Hi!
So remove the head shim! It is only there to have a proper timing! Has nothing to do with sealing at all.

XJet

A low compression ratio will not cause the engine to run fine and then suddenly stop.

Such symptoms almost always boil down to fuel, fuel system or glowplug.

Something is putting the fire out and that's either a loss of plug heat (which may be gradual due to an inadequate catalytic effect brought about by stale fuel or a weak plug) or the engine going lean through fuel restriction/air ingestion.

These aren't complex machines, just keep eliminating the possibilities and the cause will be whatever remains :-)

estradajae

I'm agree with you Xjet. I wouldn't have said it better.

Í've checked carb, needle and everything is fine..perhaps the glow plug as you've said is not working anymore. Sometimes it's not easy to find how healthy is the plug, because it may looks nice but it may not be doing the job. I'll tell you when I got the chance to run the engine again, I'll change the plug and see what happens.

Thank you for your input.

Jorge

Sport_Pilot

That is not the premise of my advise. I was commenting on the first post which said it would quit on a sudden throttle up or throttle chop.

estradajae

It was refered to Jaka's post.

Jorge