GMS .32 needle reset
02-22-2006 | 05:29 PM
#1
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From: Ithaca,
NY
GMS .32 needle reset
Hi, I bought a GMS .32 engine, so I'm having problem with it, When I go to full throttle it dies, I started to play with the needles and now it is doing worst [
]. I was wondering if somebody knows the factory carburetor setup.
Thanks
]. I was wondering if somebody knows the factory carburetor setup.Thanks
02-22-2006 | 06:59 PM
#2
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RE: GMS .32 needle reset
I have 4 of them. Pretty good little engine.
Open the needle up 3 turns or so and crank. LEAVE THE BATTERY ON. advance the throttle slowly until you are at full power. Now lean out to a peak and richen up 3-4 clicks.
If it still won't go to full power from idle, you probably have a bad plug.
My buddies are always carnking up and snatching the battery off, then wonder why it quits sometimes when they power up. The crankcase may be full of fuel and douses the plug. I think it is best to crank at a high idle, then slowly advance the power to blow out the crankcase. Then I idle down, remove the battery and go fly. Much more reliable.
You also might want to check the low end needle on the throttle arm side. At idle for 15-20 seconds, then flip to full power. If it chokes and spits, it's way too lean. Open, screw out, the low end needle a quarter turn. If it revs up slowly and smokes on the way up, it's way too rich. Close, screw in, the low end a quarter turn. Once you get close, go to 1/8 or 1/16 turns. Most engines have the low end set rich at the factory so expect this unless you have been playing with it.
If you have the low end totally messed up here is an old trick from Super Tigre from the 1970s. Hook a long piece of fuel tubing to your fuel nipple instead ot the tank line. Stick a T-pin in the carb and close the carb so it holds the pin. This is to get a small opening. Screw the idle needle carefully in until it is about closed. Blow through the fuel line, put your ear down near the carb and slowly open, screw out, the needle. When you hear a hiss, stop. This is a good starting needle setting.
As I said, I have 4 in twins and a buddy has 2 in a TwinStar. We started with 9-6 props and had loads of trouble. I had one engine go sour, just wouldn't keep running. Another fractured the lower con rod bushing, which went through the engine. Hobby Services from Tower replaced both engines. We have since started using 10-6 props to keep the rpm down a little and have had much better results. I have the second replaced .32 on my break-in plane, a Little Stick, and it is running great. I am running a 10-6 and can hover the plane for a while so it has plenty of power on the larger prop. I might try something like a 9-7 or 9-8 on my TwinStar later on.
Open the needle up 3 turns or so and crank. LEAVE THE BATTERY ON. advance the throttle slowly until you are at full power. Now lean out to a peak and richen up 3-4 clicks.
If it still won't go to full power from idle, you probably have a bad plug.
My buddies are always carnking up and snatching the battery off, then wonder why it quits sometimes when they power up. The crankcase may be full of fuel and douses the plug. I think it is best to crank at a high idle, then slowly advance the power to blow out the crankcase. Then I idle down, remove the battery and go fly. Much more reliable.
You also might want to check the low end needle on the throttle arm side. At idle for 15-20 seconds, then flip to full power. If it chokes and spits, it's way too lean. Open, screw out, the low end needle a quarter turn. If it revs up slowly and smokes on the way up, it's way too rich. Close, screw in, the low end a quarter turn. Once you get close, go to 1/8 or 1/16 turns. Most engines have the low end set rich at the factory so expect this unless you have been playing with it.
If you have the low end totally messed up here is an old trick from Super Tigre from the 1970s. Hook a long piece of fuel tubing to your fuel nipple instead ot the tank line. Stick a T-pin in the carb and close the carb so it holds the pin. This is to get a small opening. Screw the idle needle carefully in until it is about closed. Blow through the fuel line, put your ear down near the carb and slowly open, screw out, the needle. When you hear a hiss, stop. This is a good starting needle setting.
As I said, I have 4 in twins and a buddy has 2 in a TwinStar. We started with 9-6 props and had loads of trouble. I had one engine go sour, just wouldn't keep running. Another fractured the lower con rod bushing, which went through the engine. Hobby Services from Tower replaced both engines. We have since started using 10-6 props to keep the rpm down a little and have had much better results. I have the second replaced .32 on my break-in plane, a Little Stick, and it is running great. I am running a 10-6 and can hover the plane for a while so it has plenty of power on the larger prop. I might try something like a 9-7 or 9-8 on my TwinStar later on.
02-22-2006 | 07:29 PM
#3
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RE: GMS .32 needle reset
ORIGINAL: Ed_Moorman
I have 4 of them. Pretty good little engine.
Open the needle up 3 turns or so and crank. LEAVE THE BATTERY ON. advance the throttle slowly until you are at full power. Now lean out to a peak and richen up 3-4 clicks.
If it still won't go to full power from idle, you probably have a bad plug.
My buddies are always carnking up and snatching the battery off, then wonder why it quits sometimes when they power up. The crankcase may be full of fuel and douses the plug. I think it is best to crank at a high idle, then slowly advance the power to blow out the crankcase. Then I idle down, remove the battery and go fly. Much more reliable.
You also might want to check the low end needle on the throttle arm side. At idle for 15-20 seconds, then flip to full power. If it chokes and spits, it's way too lean. Open, screw out, the low end needle a quarter turn. If it revs up slowly and smokes on the way up, it's way too rich. Close, screw in, the low end a quarter turn. Once you get close, go to 1/8 or 1/16 turns. Most engines have the low end set rich at the factory so expect this unless you have been playing with it.
If you have the low end totally messed up here is an old trick from Super Tigre from the 1970s. Hook a long piece of fuel tubing to your fuel nipple instead ot the tank line. Stick a T-pin in the carb and close the carb so it holds the pin. This is to get a small opening. Screw the idle needle carefully in until it is about closed. Blow through the fuel line, put your ear down near the carb and slowly open, screw out, the needle. When you hear a hiss, stop. This is a good starting needle setting.
As I said, I have 4 in twins and a buddy has 2 in a TwinStar. We started with 9-6 props and had loads of trouble. I had one engine go sour, just wouldn't keep running. Another fractured the lower con rod bushing, which went through the engine. Hobby Services from Tower replaced both engines. We have since started using 10-6 props to keep the rpm down a little and have had much better results. I have the second replaced .32 on my break-in plane, a Little Stick, and it is running great. I am running a 10-6 and can hover the plane for a while so it has plenty of power on the larger prop. I might try something like a 9-7 or 9-8 on my TwinStar later on.
I have 4 of them. Pretty good little engine.
Open the needle up 3 turns or so and crank. LEAVE THE BATTERY ON. advance the throttle slowly until you are at full power. Now lean out to a peak and richen up 3-4 clicks.
If it still won't go to full power from idle, you probably have a bad plug.
My buddies are always carnking up and snatching the battery off, then wonder why it quits sometimes when they power up. The crankcase may be full of fuel and douses the plug. I think it is best to crank at a high idle, then slowly advance the power to blow out the crankcase. Then I idle down, remove the battery and go fly. Much more reliable.
You also might want to check the low end needle on the throttle arm side. At idle for 15-20 seconds, then flip to full power. If it chokes and spits, it's way too lean. Open, screw out, the low end needle a quarter turn. If it revs up slowly and smokes on the way up, it's way too rich. Close, screw in, the low end a quarter turn. Once you get close, go to 1/8 or 1/16 turns. Most engines have the low end set rich at the factory so expect this unless you have been playing with it.
If you have the low end totally messed up here is an old trick from Super Tigre from the 1970s. Hook a long piece of fuel tubing to your fuel nipple instead ot the tank line. Stick a T-pin in the carb and close the carb so it holds the pin. This is to get a small opening. Screw the idle needle carefully in until it is about closed. Blow through the fuel line, put your ear down near the carb and slowly open, screw out, the needle. When you hear a hiss, stop. This is a good starting needle setting.
As I said, I have 4 in twins and a buddy has 2 in a TwinStar. We started with 9-6 props and had loads of trouble. I had one engine go sour, just wouldn't keep running. Another fractured the lower con rod bushing, which went through the engine. Hobby Services from Tower replaced both engines. We have since started using 10-6 props to keep the rpm down a little and have had much better results. I have the second replaced .32 on my break-in plane, a Little Stick, and it is running great. I am running a 10-6 and can hover the plane for a while so it has plenty of power on the larger prop. I might try something like a 9-7 or 9-8 on my TwinStar later on.
------------
You forgot to tell them to reset the needle once the battery was removed from the glow plug. Battery powered glow plugs provide false needle settings. But you knew this - right?
02-22-2006 | 08:45 PM
#4
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RE: GMS .32 needle reset
I never set mine that close, always on the rich side. I always leave a smoke trail for the first of a flight. I guess that's why mine last so long I get tired of them and chuck them in a box. I will admit that I have been running short of engines now that we have built so many twins and I also use the old engines on seaplanes.
I usually think that changing the needle valve once a year is plenty and changing it once a month means you don't know beans about running engines.
Guys usually ask me if I want to hold the nose up, but I also rarely do this. If you're not running too lean it'll run fine with the nose up.
I don't think in all the years I have been flying models that I have had a top end change appreciably when removing the battery unless I was running too cold a plug or too low nitro. If it changes too much with an A3 or #8, the plug is bad or you're trying to run FAI fuel.
I usually think that changing the needle valve once a year is plenty and changing it once a month means you don't know beans about running engines.
Guys usually ask me if I want to hold the nose up, but I also rarely do this. If you're not running too lean it'll run fine with the nose up.
I don't think in all the years I have been flying models that I have had a top end change appreciably when removing the battery unless I was running too cold a plug or too low nitro. If it changes too much with an A3 or #8, the plug is bad or you're trying to run FAI fuel.
02-22-2006 | 10:59 PM
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From: Tokoroa, , NEW ZEALAND
RE: GMS .32 needle reset
One thing to watch with the GMS32 is that the low-speed needle has quite an effect on the hi-speed mixture. It's easy to get the situation where you've leaned out the low-end so much that no matter how much you open the main valve, it can't get enough fuel at full throttle.
Try richening up the low-end so that there's a gap between the low-speed and the spraybar when at full throttle, then tune the top end. Once that's sorted you can start playing with the idle-needle to get a good idle.
On the GMS32 I'm running a tuned pipe on I have had to deliberately set the low end needle quite rich in order to get anough fuel-flow at full throttle.
Try richening up the low-end so that there's a gap between the low-speed and the spraybar when at full throttle, then tune the top end. Once that's sorted you can start playing with the idle-needle to get a good idle.
On the GMS32 I'm running a tuned pipe on I have had to deliberately set the low end needle quite rich in order to get anough fuel-flow at full throttle.
