ORIGINAL: nevster
gents thanks for all the good advice. I will take off the carby, clean it and inspect the fuel tank.
I was running muffler pressure - just didn't show up on the photos.
I will also try an APC 11x7 prop. The fuel I'm using is 10% cool power.
At idle the motor is doing slightly under 5000 RPM.
David - the model started out as a polyester fuselage which I ''inherited'' (see attached photo) - can't remember how exactly,
and then I scratch built wings and tailplane from plans off the net. I'm also trying e-flite electric retracts.
I have considered an OPS pump - I don't think I could actually fit it in however - I'm struggling to fit in the battery
and leads for ailerons, flaps, retracts etc etc
I will let everyone know once I've tried a few modifications
Thanks again
Neville,
I was able to take some snaps of the paperwork that came with my engine (see below). As you can see, the length of the pipe (plug to max diameter) is correct at 38-40 cm. If yours is set at 38 cm (to high point not total length), that should be ok although it might be best to lengthen it to 40 cm to start with - it looks a tad short.
Is that an OPS
speed or
nitro pipe?
A few further thoughts came to mind: First, I'm not sure your fuel contains any castor oil (unless you've added some) and European engines (especially Italian engines) always recommend the use of a good 50% of castor. You might want to try Omega 10% if Morgan is the fuel you can source as it has 30% castor lubrication which should be just enough to keep the engine happy. Otherwise, Morgan 4-stroke (Cool Power or Omega) contains 50/50 lubrication and is a 15% nitro blend. Could turn out to be a good fuel for it.
As mentioned by others, the 11x9 prop is too much. These engines are designed for high rpm on an 11x7 prop. Max torque is achieved very close to max rpm unlike later design long stroke engines. An idle of 5000 rpm sounds like definitely too much. You should be able to get it down. Also, check the high speed needle for leaks as the carbs had a rather "loose" needle/o-ring fit that could leak if the o-ring wasn't in good shape. You might also want to try a cold plug like a Rossi R4 and R5 if you keep your fuel at 10% nitro or less.
BTW, that looks like an 8 mm carb but given the black needle valve, I'm not so sure - it could be a 9 mm carb. Please confirm which one. Whatever the carb, if you can get a pump on it, it will behave better. it shouldn't be necessary with an 8 mm carb though. I'd get it running right on an 8 mm carb first and then go from there.
Let us know how it goes!
David