2 Stroke Glow Engine questions
07-30-2007, 07:14 PM
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2 Stroke Glow Engine questions
Hey gang...
I'm running two planes, with two different engines... Magnum .91XL and Super Tigre G-90... I pretty much completely forgot how to dial these engines in for peak performance/proper mixture.
On the Magnum, it is in a CG Extra with a 14-6 Master Airscrew Prop. This is a used engine and came with the plane when I purchased it. It ran fine, but I had to get a new carburetor for it, as I broke the low speed idle needle valve (on the throttle side). I put it on, thinking it was set to factory specs... and I can't keep this plane running. The engine is rich I feel.
On the Super Tigre, it's in a Seagull Edge 540v2, with a 14-4W APC Prop. This engine started right up and runs fine, but the throttle response is sort of delayed and I can't seem to make myself happy.
For both engines, what is a good starting point to get these dialed in and running right? I'm thinking about closing all the needles, and then starting at 2-3 turns out on the high speed side, and one to two turns out on the low speed... Is this right? Any one have a better grasp on fine tuning?
The supertigre was nearly new, just a few tanks through. With the prop, and muffler... it's a lot more quiet and feels stronger than the magnum. The magnum has a pitts style, and was used. Both have good/tight compression and the cylinder walls dont have any scratches to indicate bad rings. These were also oiled and and covered prior to having them sit, and i shot more oil in before I started them just to keep things up and up.
And for the haters... Yeah I prefer O.S., but the budget doesn't allow for new engines just yet
I'm running two planes, with two different engines... Magnum .91XL and Super Tigre G-90... I pretty much completely forgot how to dial these engines in for peak performance/proper mixture.
On the Magnum, it is in a CG Extra with a 14-6 Master Airscrew Prop. This is a used engine and came with the plane when I purchased it. It ran fine, but I had to get a new carburetor for it, as I broke the low speed idle needle valve (on the throttle side). I put it on, thinking it was set to factory specs... and I can't keep this plane running. The engine is rich I feel.
On the Super Tigre, it's in a Seagull Edge 540v2, with a 14-4W APC Prop. This engine started right up and runs fine, but the throttle response is sort of delayed and I can't seem to make myself happy.
For both engines, what is a good starting point to get these dialed in and running right? I'm thinking about closing all the needles, and then starting at 2-3 turns out on the high speed side, and one to two turns out on the low speed... Is this right? Any one have a better grasp on fine tuning?
The supertigre was nearly new, just a few tanks through. With the prop, and muffler... it's a lot more quiet and feels stronger than the magnum. The magnum has a pitts style, and was used. Both have good/tight compression and the cylinder walls dont have any scratches to indicate bad rings. These were also oiled and and covered prior to having them sit, and i shot more oil in before I started them just to keep things up and up.
And for the haters... Yeah I prefer O.S., but the budget doesn't allow for new engines just yet
07-30-2007, 08:25 PM
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RE: 2 Stroke Glow Engine questions
Hi Fear.. my tip for initial settings for low idle:
1. Screw it in all the way, but do so gently. Once you feel resistance from closing, stop.
2. Attach a piece of fuel tubing to the carby fuel inlet and apply air pressure to it. You know how to do that don't you? Just put it between your lips and blow. Ummm... had a Marilyn moment there, sorry. Anyways...
3. Slowly turn out the low idle needle until you hear/feel air escaping past it. Screw it out a little further just to make sure it's set a little rich.
This should give you a reasonable starting point, and at least allow the engine to idle, albeit it at a rich setting.
Initial setting for high speed needle should be 3-4 turns out. Again, this will ensure it's nice and rich and will allow you to tune it in.
With regards to fine tuning once you have it running, search the forums for process.. there are a few approaches you will turn up, all claiming to be the best way. Do what I did.. try one and see how it goes. If it doesn't work, give the next method a try, etc... you'll get there in the end! At the end of the day, it's all about a steady idle and a smooth transition from low to high RPM.
FYI, I am a fan of the old "pinch test" for low idle settings, and a "-200 rpm rich" method for high speed settings.
Hope this helps!
1. Screw it in all the way, but do so gently. Once you feel resistance from closing, stop.
2. Attach a piece of fuel tubing to the carby fuel inlet and apply air pressure to it. You know how to do that don't you? Just put it between your lips and blow. Ummm... had a Marilyn moment there, sorry. Anyways...
3. Slowly turn out the low idle needle until you hear/feel air escaping past it. Screw it out a little further just to make sure it's set a little rich.
This should give you a reasonable starting point, and at least allow the engine to idle, albeit it at a rich setting.
Initial setting for high speed needle should be 3-4 turns out. Again, this will ensure it's nice and rich and will allow you to tune it in.
With regards to fine tuning once you have it running, search the forums for process.. there are a few approaches you will turn up, all claiming to be the best way. Do what I did.. try one and see how it goes. If it doesn't work, give the next method a try, etc... you'll get there in the end! At the end of the day, it's all about a steady idle and a smooth transition from low to high RPM.
FYI, I am a fan of the old "pinch test" for low idle settings, and a "-200 rpm rich" method for high speed settings.
Hope this helps!
07-31-2007, 06:38 PM
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RE: 2 Stroke Glow Engine questions
U really think it needs to swing something bigger? I just ordered a few new ones to try... i forgot what good manufacturers of props were... I have a few MAS props laying around, one is a wood scimitar that's 14-6... and then i have a few of their sport props that are glass filled nylon around that same size... will have to check. I ordered another APC, none in 15" dia tho.
Yes, the magnum will idle. It's wierd. I can get it howling like the wolves at level, when brought up to vertical, it stays consistent, but if i put the nose at a downward angle it dropped RPMS... aduable enough to sound like the throttle was chopped in half.
Still waiting on the new fuel tank for the extra/magnum combo.
Yes, the magnum will idle. It's wierd. I can get it howling like the wolves at level, when brought up to vertical, it stays consistent, but if i put the nose at a downward angle it dropped RPMS... aduable enough to sound like the throttle was chopped in half.
Still waiting on the new fuel tank for the extra/magnum combo.
08-01-2007, 01:06 PM
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RE: 2 Stroke Glow Engine questions
I have had a bunch of ST90s. The best sport props are a 14x6 and a 13x8. The best 3D prop is a 15x4W. I tried a 14x4W on one. It was a heavy model but the prop was terrible. The 14x6 and 15x4W both out pulled it. I hovered the plane with all three. The 14x6 took 90% throttle the 15x4W took 75% throttle and the 14x4W would not hold the hover for very long at 100%. Maybe a lighter plane would be different but you still gotta figure the other two props are better.
David
David
