Super Tigre .51 2-stroke problems

[warbirdlover15]

I had bought this engine in an auction and have run it once with great reasults, then I had installed it into a plane (hanger 9 p-51 sport 40). I was able to get it started but when I tried to advance the throttle, it would quit or when I would remove the glow plug or screw in the high speed needle from the origonal starting position (which is 3 turns). I then set the low speed to the original position and I was able to advance the throttle to full but with the high speed needle still at 3 turns instead of 2 and a quarter.
engine is also inverted

Neeeed help please!!!!!

[Dale Hunter]

Michael, welcome to R/C Canada!
Feel free to call me (780 672 0927), I get down that way regularly. Always a lot easier to diagnose in person.
In the meantime, I'd start by looking at the tank set-up. Possibly a pinched fuel line, by the foam maybe. Or a air leak, pinhole. If you take the tank out, block all but one line hold it under water and blow proving no pinholes in lines.
If it ran good on a test bench then it WILL run good, after your problem is located and recktified (me bad speller!)

-Dale-

[aceplant00]

probably an issue with the engine being inverted. 2 strokes do no like being inverted. Best on side of head side up.

[Cougar429]

First thing is to install a 4-stroke plug. When inverted the fuel/oil has a tendency to flow down into the plug bore. This reaction pretty much happens with anything beyond side mounting, getting worse as you mount towards inverted. 4-stroke plugs, such as an OS "F", remain hot longer due to the need to stay lit on the intake'exhaust stroke and do a better job of burning off that fuel and oil.

Dale Hunter is also likely pointing out an important point. Normally with the engine mounted right side up the centerline of the tank will line up with the center of the carb. Flipping the motor inverted places the tank much higher in relation to the carb and can exacerbate the mixture. One way you can check is to try and run the motor with the plane supported inverted. Another indication is this: if fuel is leaking from the carb with the engine stopped and full throttle then you have your fuel tank too high in relation to the carb. I had the same problem on my Harvard II and it took a bit of work to get the positions correct.

You never mentioned how it idles, so I'm making the assumption it is stable. One thing to try is to pinch the fuel line while idling and then see if the motor simply dies or if it momentarily speeds up. If so this is an indication the LS needle is set too rich.

Not sure on ST settings, but with every other motor I have you normally start with the HS needle 1 3/4 turns out and the LS needle flush with the throttle arm. Once you have them close adjust the HS needle at full throttle, then work down to idle, adjusting the LS needle for a stable idle. You may have to do several throttle ups to see how it accelerates. If it stalls then you likely are still too lean. If it stumbles and burps oil and smoke you are too rich. The perfect condition will have it able to idle forever and still transition smoothly to full throttle.

NOTE: You will want to do the final adjustment to the HS needle, richening a couple of clicks from peak to ensure you will not have a lean run when airborne.

All this is predicated on having a mechanically sound engine. Air leaks in the carb mounting or crank bearings will make the motor require an overrich setting to compensate.

p.s. I'm not trying to be condescending with these instructions. Just do not know what your experience level is and am trying to cover as much as possible.

[SpaceCowboy]

I would recommend using an idle bar glow plug for inverted installation. I always used an FOX Standard idle bar plug in my .75's and 45's even though they were mounted sideways.

The ones made in Italy had to have the low speed adjusted about 3 -4 turns rich out of the box.