Zen G26 Carb Adjustments - Help
05-15-2008 | 08:27 AM
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Zen G26 Carb Adjustments - Help
Flew my Zenoah G26 for the first time yesterday .... both landings were dead-stick. This is my first gasser ... so I am not familiar with the tips/tricks on carb adjustments. No problems at 60 % (or higher) throttle settings ..... but after flying for 3-4 minutes, when I went to 1/2 throttle (or lower) it seemed to load up/be too rich. The manual states that the Low Speed Needle should be set 1/4 open from best mixture ... should this be done at full throttle ? half ? idle ? I was using an APC 16 X 10 prop. Any ideas ? Thanks. Bob
05-17-2008 | 05:08 AM
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From: Miami,
FL
RE: Zen G26 Carb Adjustments - Help
Hay bob i know it is a killer when no one post a response. I to am new on the gas aspect i will ask some of the guys out at the field on sunday a lot of gassers they will be more then glad to help. I ill get back to you.
05-17-2008 | 07:37 AM
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From: Mount Dora,
FL
RE: Zen G26 Carb Adjustments - Help
Bob,
just go back to the standard settings for the G-26.
a. Low-Speed Needle: 1 1/8
b. High-Speed Needle: 1 3/8
The 1/4 open from max rpm is only on the high speed needle. Try the standard settings and let me know how you do. You could even start at 1 1/4 and 1 1/2 to stay a bit rich but the stock settings work fine. How did you work out max rpm?
What plane do you have it on. I use a 17x8 Xoar prop and have a huge amount of success on it. i las had it on a 16.5 pound Giant Thunderbolt and it flew it well.
good luck
Paul
just go back to the standard settings for the G-26.
a. Low-Speed Needle: 1 1/8
b. High-Speed Needle: 1 3/8
The 1/4 open from max rpm is only on the high speed needle. Try the standard settings and let me know how you do. You could even start at 1 1/4 and 1 1/2 to stay a bit rich but the stock settings work fine. How did you work out max rpm?
What plane do you have it on. I use a 17x8 Xoar prop and have a huge amount of success on it. i las had it on a 16.5 pound Giant Thunderbolt and it flew it well.
good luck
Paul
05-18-2008 | 01:37 PM
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RE: Zen G26 Carb Adjustments - Help
Yes, I had seen those instructions I certainly would have followed them .... who wouldn't ? As I noted previously, this is my first gasser .... so I had not really had the chance to spend a lot of time in this forum.
06-28-2008 | 05:14 PM
#8
RE: Zen G26 Carb Adjustments - Help
The 26 has the the regulator side of the carb facing the wind blast which is higher in flight than on the ground. The reference hole in the little cover needs to have a tube soldered in, a short piece of tygon put on and inserted into the fuse where the pressures SHOULD remain constant. The way it is stock, as the airspeed picks up the reference hole picks up increased pressure which presses down on the diaphragm holding the needle open more than normal resulting in a rich mixture when you throttle back. It may take a little experimenting to find a spot where the pressures remain constant and don't influence the carb mixture. You can search for pics of the mod here on RCU, that's how I found out how to do mine and it really helped. Good luck.
07-02-2008 | 06:08 PM
#11
RE: Zen G26 Carb Adjustments - Help
ORIGINAL: BalsaBob
That would explain why it runs good on the ground ...... and then eventually quits in the air. Is there a modified cover available from Zenoah .... or another company ?
Thanks. Bob
That would explain why it runs good on the ground ...... and then eventually quits in the air. Is there a modified cover available from Zenoah .... or another company ?
Thanks. Bob
Edited to add:
In addition to the way shown in this picture, I've seen guys solder the existing hole shut and drill and tap the center of the plate and screw a small brass fitting in like those used for muffler pressure. I put a hose on mine and run it inside the fuselage.
07-04-2008 | 06:18 AM
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From: Spiceland,
IN
RE: Zen G26 Carb Adjustments - Help
the guys that are telling you to solder the tube on are dead on. I had this same issue on my b-25 this summer. Also, I picked up 800 rpm with the stock velocity stack on, as opposed to off. I had engine out flights and etc.. until I these changes were made..
07-04-2008 | 11:34 AM
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RE: Zen G26 Carb Adjustments - Help
ORIGINAL: Jezmo
The 26 has the the regulator side of the carb facing the wind blast which is higher in flight than on the ground. The reference hole in the little cover needs to have a tube soldered in, a short piece of tygon put on and inserted into the fuse where the pressures SHOULD remain constant. The way it is stock, as the airspeed picks up the reference hole picks up increased pressure which presses down on the diaphragm holding the needle open more than normal resulting in a rich mixture when you throttle back. It may take a little experimenting to find a spot where the pressures remain constant and don't influence the carb mixture. You can search for pics of the mod here on RCU, that's how I found out how to do mine and it really helped. Good luck.
The 26 has the the regulator side of the carb facing the wind blast which is higher in flight than on the ground. The reference hole in the little cover needs to have a tube soldered in, a short piece of tygon put on and inserted into the fuse where the pressures SHOULD remain constant. The way it is stock, as the airspeed picks up the reference hole picks up increased pressure which presses down on the diaphragm holding the needle open more than normal resulting in a rich mixture when you throttle back. It may take a little experimenting to find a spot where the pressures remain constant and don't influence the carb mixture. You can search for pics of the mod here on RCU, that's how I found out how to do mine and it really helped. Good luck.
I concur 100%!
If you want, you can run the tube out the bottom of the cowl, and bevel the bottom of the tubing at a 45 degree angle so that the bevel is facing backward. THe factory velocity stack is also an important part to install. It will eliminate alot of the turbulence in the air entering the carb, which wil alow more constant mixtures.
