I have a G-26 Zenoah engine on a ultrastick lite. The problem is that I can play with the throttle on the ground and it is very responsive, but in the air the throttle is very slow to respond to changes. I can put it from low to full in an instant, but the engine will take about 1 to 2 seconds to respond. Any ideas?
Bill R.

Engines tend to run richer in the air. Could be foaming caused at the higher speeds. Is your gas tank well padded and insulated from the airframe? I've actually never run into this with a gas engine, so I don't know that gas/oil mix foams like glow fuel does. Might want to ask this of the Gas Engines forum here.

Also, sound travels about 600 fps so if your plane is 1,200 feet away it takes two seconds for the sound of the throttle change to reach your ears.

A G-26 on an Ultra-stick Lite...An Ultra-stick LITE????????????? Uhh, you mean of course the 1.20 size plane....I have a G-26 in a Stearman and have no throttle lag, but then again I don't "slam" the throttle to wide open, haven't had to as of yet.

yeah it is the Ultrastick lite 120. A friend of mine did the job of the G-26. It involved moving one servo all the way to the very end of the tail and chopping the nose off. It has tremendous power, but is very touchy. I think it is a mixture problem. The lag shows in power as well as sound. It is really responsive at low altitude and on the ground, but above 100 feet or that far away.... you can see that it gets worse with the increasing distance. The other controls are not like this... they work perfectly.
So Should I work on low as well as the high end? I have always heard that the low end mixture is the transition mixture. Advice?
Bill R.

Bill,

You're lucky the engine hasn't died in the air yet. I had a G26 on the same plane, ran great on the ground, would die in the air or on landing or just not put out power. After reading in the gas forum, I installed a brass fitting on the metering diaphragm cover and ran a piece of tygon tubing inside the fuselage. Problem solved. What is happening is varying air pressure is acting on the metering diaphragm affecting the air fuel mixture while the plane is in the air. With the tubing running inside the fuselage, that pressure variation is minimized. The carb on the G26 is a tad bit big so it makes tuning very touchy.

I wrote this in a thread in the Gas Forum sometime back regarding the same issue on a G26:

"4. Next and most important, assuming your mixture screws are facing down toward the ground which is the common installation. In this position, the fuel metering diaphragm is facing into the prop wash, ie forward. The variable atmospheric pressure from the prop and air stream effects the performance greatly by my experience. The engine runs fine on the ground, but sucks when it's airborne. Then you begin to chase your tail to adjust the carb to no avail. My G26 was initially installed on an Ultra Stick Lite with the engine exposed like on your plane. I had a least a dozen dead sticks and a crappy running engine until I took the advice to solder a fitting on the metering diaphragm cover in order to run a vent line into the fuselage and to plug the exist hole with silicone. Engine now ran sweet on the ground and great in the air, day and night difference, no more dead sticks. Well the plane ultimately crashed and the engine is now on a profile plane with the engine fully exposed again. Since it was a profile, I didn't run the vent line into the fuselage, just ran it back under the fuselage. You guessed right, the sweet running engine now didn't run worth a darn. Two of the first three flights were deadsticks. The vent line is now inside the fuselage, engine runs great and no more deadsticks."

Good luck and let us know how it goes.

Chuck

I don't know why the pictures are showing up, RCUniverse must be having a problem this morning. Pictures weren't showing up in the thread where I copied the quoted paragraph. PM me with your email address and I'll send you the pictures showing what you have to do.

Thanks for the help Chuck! How much of a difference did it make? It sounds exactly like what is happening to me. Mine will almost die, but it kicks and sputters just enough to stay alive. I will work on that solution tonight. Have you ever heard of any replacement carbs for the G26 the are a little better?

Bill R.

Bill,
It was a day and night difference. No more deadsticks, and a great running little engine. There are replacement carbs, namely the carb used on the G23, but I wouldn't do that unless you really have to. This is a quote from RCIGN1 on how to set the carb on the G26:

"The low is too rich and is affecting the high...Typical low setting is about 1 1/3 to 1 1/2, then with the low leaner you will have to re set the high...
The carb on the G26 is pretty big for the size of the engine and needs to be set a little differently..Open both about 2 turns...Set the idle speed at about 2000 rpm and slowly lean out the needle.(If it won't idle at 2000 it's way rich on the low needle.)..The idle speed will increase..Re set to 2000 and continue leaning..When the speed no longer increase...Go back and try the transition..If not good slowly open the low needle a little at a time until the transition is good, and re set the high...I think you will find both needles open about 1 1/3 to 1 1/2 after adjusting this way...A 16-8 and an 18-6 will both turn about the same, but the 18-6 will pull harder and fly the plane slower..Depends on what you want...A non restrictive noisy exhaust diverter will give you about more rpm..It should idle at 1800 when correctly set.... "

This quote came out of this thread:
http://www.rcuniverse.com/forum/m_37...tm.htm#3702497

Chuck

I agree with what Chuck said about running a tube from the carb. diaphram cover to inside the plane. I 've had to do this on many of my gas planes.
I also have a Ultra Stick Lite with a G-26 but you can see by the picture that the carb. diaphram is facing the rear, I have had no problems with this carb. position and didn't install the tube on the diaphram cover.
This plane flyes very good with good throttle responce and no dead sticks.

Well.... I got the plane out this weekend and looked at the carb to go buy a tube for all of the suggestions above.... but.... no went hole as pictured. I cannot find the vent hole on any of the sides... have not checked the bottom though. I guess I am going to have to work with the mixtures... any suggestions?
Bill R.

Does your carb have the needles at the front, if so the metering hole is usually on one side of the front cover that is held on by four small screws. Remove the cover plate being careful not to damage the diaphram below. Drill a suitable size hole in the center of the plate and silver solder in a short piece of brass tubing or a brass nipple making sure that it is flush with the inner face of the plate.

Use solder or high temp silicone to block the original hole in the plate and reassemble. Connect a length of gas tubing to the new fitting and run it into the fuse via a hole in the front bulkhead and your problems should be over. HTH

Karol

Look at the picture I sent you. The square plate held on by the four screws is where the vent hole is located. The hole is very small and is on the raised part that is a circle shape.

I've got a G26 in one also. I moved both servos to the tail on the sides of the fuse. I didn't cut the nose down. It was a bit nose heavy and then I sent the G26 to Ralph for conversion. He took almost a pound of the motor. The plane flys awsome and I even use it for a trainer for my buddies on the buddy box.

If Drone Pilot is freaking out about a g26 the he should drop when he finds out I have a brison 2.4 on my USL that 40 cc.
I had the same problem had to add a tube to the vent and ran it inside the Fuse,has ran great since.
I have made this mod. to all my gassers straight out of the box.
WYLDMAN

I also have a US Lite with a G-26 and the nose chopped off. My G-26 is stock right down to the muffler and it runs flawless in any attitude with out any mods. One thing I would suggest though is if you have the tan colored carb block, (like in L48's pic above) they have been known to crack and leak. No amount of tuning or mods will mask a airleak. I have the black bakelite one on my engine and it has been leak free.

Haven't had a problem with this block so far, does the black block keep the carb. in the same position or does it rotate it?

The black block was made to fix the cracking problem with the tan block...Both rotate the carb to make the shaft parallel to the cylinder...

Unless its and NOS engine then the black block is the orginal intake and puts the carb at a funny angle. How to tell them apart??? Install it and see what it does to the carb.
TKG

G62 carb insulator block 101..Shiny black, Horizon aftermarket...
Dull black, stock Red Max chainsaw, used also on the G62 airplane engine...Some kind of plastic material, not strong enough for good threads...
Bakelite is molded from layers of linen, is brown....That's why the Horizon tan block cracks...
The bakelite brown block is too weak to be tapped without something else in the hole, there are inserts in the block...Shiny black block has no inserts, threads are in the block..Dull black block has no threads in it, the carb bolts go all the way through to the cylinder...

Hi Ralph,

Sent you an e-mail a couple days ago and followed up with a PM, and wondered if you received any of them ?

Karol