Question on carb needle settings on engine from Newbie.
01-01-2006 | 09:40 AM
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From: Wallingford,
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Question on carb needle settings on engine from Newbie.
Hello all,
I have a few questions on engine settings from a newbie.
First of all, I bought a Thunder Tiger .46 Pro about 6 years ago and can't find the manual. If someone can send me a pdf or point me in the direction of a pdf of it on line, I'd really appreciated it.
Secondly (and sadly), I'm just breaking in this engine and I am trying to understand the needle settings on the carburetor. I know there is a low end and a high end, but I'm not sure what each one does, or where to set each one. I did get the engine running and realized that the carburetor was set too lean because the engine would stall at higher RPMs. I opened the high end needle up until I could just run the engine at the higher RPMs. I let the engine run for 5 minutes, and will do so a few more times to break it in.
Is this where I want the carburetor needles set for break-in? And once the engine is broken in, do I want to open the carburetor up a little bit more to run a little more rich for better cooling? I'm not sure why there are two needles (high and low), instead of just one. Isn't it just the gap between them that determines how the engine runs?
Finally, does anyone know the default needle settings for the Thunder Tiger .46 Pro?
Thanks for any help/advice you can offer.
-Tux
I have a few questions on engine settings from a newbie.
First of all, I bought a Thunder Tiger .46 Pro about 6 years ago and can't find the manual. If someone can send me a pdf or point me in the direction of a pdf of it on line, I'd really appreciated it.
Secondly (and sadly), I'm just breaking in this engine and I am trying to understand the needle settings on the carburetor. I know there is a low end and a high end, but I'm not sure what each one does, or where to set each one. I did get the engine running and realized that the carburetor was set too lean because the engine would stall at higher RPMs. I opened the high end needle up until I could just run the engine at the higher RPMs. I let the engine run for 5 minutes, and will do so a few more times to break it in.
Is this where I want the carburetor needles set for break-in? And once the engine is broken in, do I want to open the carburetor up a little bit more to run a little more rich for better cooling? I'm not sure why there are two needles (high and low), instead of just one. Isn't it just the gap between them that determines how the engine runs?
Finally, does anyone know the default needle settings for the Thunder Tiger .46 Pro?
Thanks for any help/advice you can offer.
-Tux
01-01-2006 | 01:08 PM
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From: Chesterfield, MO
RE: Question on carb needle settings on engine from Newbie.
the TT .46 is a great engine. There are 2 NV so you can adjust the mixture at IDLE independently of the higher settings. The high speed NV is the big stick about an inch long. You adjust this with the engine running at full throttle. Just be careful to avoid the prop. The low-speed is adjusted with a very small straight-bit screwdriver inserted into the end of the carburetor barrel. You adjust this to get a nice idle and transition from idle. You have to do this one with the engine off. make the adjustment, start the engine, test for good idle and transition, then shut the engine off and try another setting. repeat until the idle and transition is good.
The high speed NV should be set slightly more open (CCW) from the peak rpm setting. perhaps three or 4 clicks from peak. start with the HS NV at 2.5 turns open (close it until it stops and then open 2.5 turns). start the engine at full throttle. Most glow engines will run at full throttle with the HS NV set anywhere from 3 or 4 turns open to 1.5 turns open. The "right" spot is somewhere in between. Glow engines will run at full throttle with the low speed NV set anywhere, so don't worry about the LS NV until the engine runs well at High speed and is broken in a little. while the engine is running at full throttle, turn the HS NV clockwise until the engine speeds up. Only do a few clicks at a time, then wait a second or two for the engine to respond. keep closing until the engine gets to its maximum speed. you can tell this from the sound. at some point the engine will go no faster and then it will begin to slow down again. you have found the peak setting, so open the needle valve until it slows down a little. you always want to run the engine on the rich (open) side of the peak setting. Another test to determine if you are rich or lean is to pinch the fuel line (between the tank and carb) with your fingers while te engine is running at full throttle. Pinch it off completely for about 1/2 second. You should hear the engine speed up a little. if it quits immediately, you are too lean. If it is set properly, the pinch test should cause it to speed up for that 1/2 second time frame and then continue to run. If you pinch the fuel line off for more than 1/2 second, of course, any engine will quit eventually.
The high speed NV should be set slightly more open (CCW) from the peak rpm setting. perhaps three or 4 clicks from peak. start with the HS NV at 2.5 turns open (close it until it stops and then open 2.5 turns). start the engine at full throttle. Most glow engines will run at full throttle with the HS NV set anywhere from 3 or 4 turns open to 1.5 turns open. The "right" spot is somewhere in between. Glow engines will run at full throttle with the low speed NV set anywhere, so don't worry about the LS NV until the engine runs well at High speed and is broken in a little. while the engine is running at full throttle, turn the HS NV clockwise until the engine speeds up. Only do a few clicks at a time, then wait a second or two for the engine to respond. keep closing until the engine gets to its maximum speed. you can tell this from the sound. at some point the engine will go no faster and then it will begin to slow down again. you have found the peak setting, so open the needle valve until it slows down a little. you always want to run the engine on the rich (open) side of the peak setting. Another test to determine if you are rich or lean is to pinch the fuel line (between the tank and carb) with your fingers while te engine is running at full throttle. Pinch it off completely for about 1/2 second. You should hear the engine speed up a little. if it quits immediately, you are too lean. If it is set properly, the pinch test should cause it to speed up for that 1/2 second time frame and then continue to run. If you pinch the fuel line off for more than 1/2 second, of course, any engine will quit eventually.
01-01-2006 | 01:47 PM
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RE: Question on carb needle settings on engine from Newbie.
Good info from DMcQuinn, but one thing he said sounded a little confusing to me, so I'll clarify it a little in case it confused you too.
Turn the needle valve in till the engine runs at its highest RPM - Now let's say the needle is at 10 O'Clock, as you keep turning, the rpm will not change (or will change VERY little). Then, at 12 O'Clock you hear the RPM start to drop. You should return the needle to the 10 O'Clock position, and maybe 1 or two clicks toward 9 O'Clock
Also, if you are breaking in the engine, turn the needle back to 9 - maybe even 8 or 7 O'Clock so it's running fairly rich, but not sickly rich. Do that for about 2 tankfuls and you'll be fine.
Turn the needle valve in till the engine runs at its highest RPM - Now let's say the needle is at 10 O'Clock, as you keep turning, the rpm will not change (or will change VERY little). Then, at 12 O'Clock you hear the RPM start to drop. You should return the needle to the 10 O'Clock position, and maybe 1 or two clicks toward 9 O'Clock
Also, if you are breaking in the engine, turn the needle back to 9 - maybe even 8 or 7 O'Clock so it's running fairly rich, but not sickly rich. Do that for about 2 tankfuls and you'll be fine.
