Please help, I cannot get the carb adjusted properly. Upon takeoff engines sputters. When I adjust
low idle needle leaner, engine stalls in air. When I make it richer it sputters worse. Has any one
had this problem, if so please help.

Thanks!

Dale

Hey Dale,

I went through all the g90 troubles you are describing ( classic rich midrange ).The first thing I recomend is using a hotter glow plug, Im using an OS F (four stroke) plug and It seemed to help my probs no end.Ive also been told that prop selection and fuel have an effect on carb adjustment, I dont run any nitro in my fuel and have been told that big supertigres realy dont need much if any 0-5% would be fine.As far as props go. Ive tried a 13x6 (screamed its **** off),14x6 (great sport flying prop) and now run a 15x4 wide blade (awesome for 3d) all APC props,Id recomend the 14x6 as a good starting point. Ive also been told that it can takeforever to fully run in a supertigre ringed eng to a point where it becomes reliable and makes full power but I recently purchased my second G90 for a 3d plane and ran it in as per the instructions( 5 min full throttle slobbering rich and then lean out gradually to the point that it is ready to fly.I did this in the space of two 10ounce tanks of fuel and then went flying,I ve since put at least 25 flights on this plane with no deadsticks or needle adjustments whatsoever and its makeing awesome power running an OS F plug / no nitro and a 15x4w apc prop.

Hope this gives you somewhere to start

Cheers

Weedy

I've been experimenting with a well run ST G90 and found some interesting results.

Fuel: Powermaster 10%
Prop: APC 14x4w

Stock configuration: rpm: 10,500

Swap carb to Magnum 91/108 rpm: 11,500
Swap stock muffler to Ultrathrust rpm: 12,500

Magnum carb = $37.00
Ultrathrust muffler = $74.00

Bottom line: The carb swap is a no-brainer ... for $37.00 add 1,000 rpm
The muffler is a little expensive but adds another 1,000 rpm over stock. If you have an old ST G90 laying around, give it a try. Transition is great with the Magnum carb. Power with both mods is awesome... and it sounds like a high performance dirt bike!

I am going to flight test the modified ST in my Aeroworks Edge 540T 40/60 tomorrow. AUW is 6lbs.

Flight Report #1:
Engine would not run consistantly. I believe the problem was too much boost/heat using the Ultrathrust muffler. The bench runs were great with that combo, however, it was a totally different story in the plane. By the way, I switched to a Magnum 91/108 carb which has proven to work very well in the G90.

Back to the Bench:

I removed the Ultrathrust muffler and installed my OLD Jtec manifold with dual pipes. The result was a loss of 400 rpm and lower head temp. I also found that the McCoy 4 stroke plug seems to improve low-end performance. Max rpm with APC 14x4w is now 12,100

Flight Report #2:

Success! Maiden flight went very well. The modified ST G90 performed flawlessly. I was getting 12,100 rpm with a APC 14x4w which provided truly unlimited vertical. Most flying was done at 1/2 to 3/4 throttle. KE flight was extremely neutral. I didn't notice any tendency to pitch in KE flight. Upright flat spin was good but inverted was better. I have not tried 3D yet, however, the modified G90 has great thrust and throttle response. I had to cut the flying session short due to weather conditions. I'll post more as I get more flying time on the Edge.

Weedy,

Are you running the stock muffler & carb? What rpm are you getting on the 15x4w? You may be surprised how much improvement is gained by the $37 Magnum 91/108 carb alone. BTW, the Magnum 91/108 carb can be found at Ho@@yPeop@@