Magna

The instruction is simple and does not have more info. Mine thus far on 2 tank of 16 oz run great but not started with hand. Its a pain, but easy with starter.

It seems like we tune lo first and then to hi? What is the arrangement. My thus far is only on 16x6, but will try to maiden this weekend with 18x6W.

Thanks!

Tired Old Man

My Feedback: (1)

The G-26, like the G-62, requires that the prop be positioned s noted in the instructions for easy hand starting. Ralph at RCIGN could give you a more specific "clock" position for the blades.

As far as tuning is concerned, the 26 is like any other. Peak the low needle at somewhere near 2,500 to 3,000 rpm, then peak the high needle at high rpm then back off just a "touch". Now re-peak the low needle and you should be very, very close to the final running point.

Pat

Magna

Pat

What do you mean by peak the lo needle somewhere 2500-3000rpm? Do I adjust them while in idle or?

Thus far, the run in is great even at idle to mid and full. Transition seems no hesitation though I did richen both needle by 1/4 of turn. I may need to check the tach again with the 18x6w.

Do you think I get adequate airspeed with 8000rpm on 18x6w on a 13lbs Katana. Wonder if speed too slow?

Tired Old Man

My Feedback: (1)

Essentially, yes. Set the throttle at about 2.5 to 3K rpm, then peak the low needle. Then go to max rpm and do the high. That's about all there is to tuning a gasser. The whole thing was in reply to your question about how to tune a G-26.

As for you power levels, I think a G-26 is a little on the short side for a 13 pound plane, depending on what type of plane it is. For something like a Cub, it would be great. For somethig like an Extra, it may be a little short. The rpm levels you have are fine for the engine.

Pat

chuck l

My Feedback: (17)

Magna,

FYI, I'm pulling about 9200rpm with stock muffler and 17x6 APC prop. One word of caution, don't set the low speed mixture rich, the engine will die at idle while still in the air. A lot of us have been there. Get the leanest setting that will allow the engine to transition to full throttle, plus keep your idle a little high (200rpm) until the engine is broken in to help prevent deadsticks.

Chuck

tande

My Feedback: (48)

"Amen"

RTK

My Feedback: (1)

Set the low needle for an idle of about 1800 rpms, with so sagging or loading up when transitioning. Then Peak the high and back off a hundred or so.
The best prop for this engine is a 18x6 mejz. Should run 9000+/- with a free flowing exhaust.

pe reivers

All In all, Silversurfer said it. [link=http://www.prme.nl/forum/viewtopic.php?t=10]More detailed instructions have been posted here[/link] with follow up fine tuning after the engine (typo edit) has been run in.

Tired Old Man

My Feedback: (1)

That's a good thread/manual for engine tuning. It wouldn't hurt for many to download it for future reference.

Preivers, thank you.

Pat

Magna

Thanks all for the info. been very helpful.

Magna

OK! I tried the above tuning ie tune the lo first. This is what I encounter.

When I idle at about 2.5-3k, I slowly peaked the lo ie leaning it out. The rpm increased substantially to almost 4.5k. Then I backed off a bit. Later move on to hi needle and do the setting as recommended. Somehow I may have missed something as I felt that its overleaning ie engine quit as I reached WOT.

When I peak the lo needle, I felt that I can turn almost 3/4 or a turn. At any rate it kind of messed up so I started over again with factory setting + 1/4 turn open. Fire right up with a flip and then idle hi/well. Max speed seems to be good compare to earlier run. I got 18x6w at 7300 vs 7000 rpm earlier on. I did not do any thing else and it transition just ok except if I push the throttle WOT fast from 5 sec idle, it will hesitate and almost died. It seems to bog down and wanting to cut, only with quick return to mid/lo throttle the engine stay running. What happen here?

I managed to squeze in 2 flights with 18x6w on 7300rpm. I did not touch the lo end needed.

But if I push the throttle to WOT slowly, its OK. So my tuning essentially still not right.

With most of the rpm reading here I believe I should get 8000rpm with 18x6w on standard muffler so I got some way to go to get that remaining 700rpm. So I should do the following right?

#1 Idle at 2.5k rpm
#2 Peak the lo needle
#3 Then go WOT
#4 Peak the hi needle
#5 repeat step 1-4 until I get best possible rpm?

How do I know I'm over lean/heating? I can feel it when the smell of exhaust started to get heated up in the earlier tuning session.

RTK

My Feedback: (1)

Here is the easiest way I have found to set the needles on any engine. Fine tunning will follow when flying in the air.

Set both needles out 2 turns
Peak the high and back off 100 or two
Keep leaning the low till it will not transition, then richen till it will (as per RGIGN1, shoot for about 1800rpm at idle)
Now re-set the high as previously mentioned

Your engine now will be set for best power and best transition. Minor tweaking will be made by how things go in the air.

Tired Old Man

My Feedback: (1)

Remember that part about backing off the high needle a little bit?????????

If it bogs during a fast transition, go back and first try bcking off the LEAN setting that you have on the high speed needle. If it still bogs during a fast transition, back off the low needle 1/16 of a turn or so. It sounds to me like you have the high end much too lean, and forgot about the backing off the top part.

If you are seeking perfect matches in rpm numbers from some source, good luck. You're going to be experimenting with props and needles for a long, long time.

Magna

Ok! I will try out the hi needle. I haven't touched anything after I reverted back to factory setting. I have not peaked the lo end yet. I will do the 4 steps again with backing off from peak.

Will let you all know how it goes.

Silversurfer, not so much of matching rpm reading with any sources, but with 7300rpm compare to most at 8000 on same prop/muffler (albeit diff elevation/atmo/fuel etc) I shouldn't be loosing that much right?

Tired Old Man

My Feedback: (1)

Depends a lot on the prop, and the veracity of the people providing rpm numbers. I have never matched someone elses numbers, only come close on one side or the other.

If you cannot attain the numbers you believe you should after tuning the engine, the issue is likely with the prop. Perhaps also the gas, but not the oil. You do have a much higher humidity level than most places in the U.S. Something to consider since it will have a negative impact on engine performance. Also remember that the engine is new and will continue to gain rpm as it runs itself in. That amount will vary considerably from engine to engine.

BTW, no prolonged periods of high rpm running on the ground. Not good at all for the engine.

DO NOT max peak the high needle and leave it there. Back off to the rich side1 or 2 hundred rpm.

Antique

My Feedback: (4)

Anything more than about 2 turns open is too far on the low speed needle and is affecting the high..
One more time...Open both about 2 turns...Peak the high..Leave it there...Set the idle SPEED with the throttle servo, you want about 1800 rpm...Lean the low slightly...The idle speed will increase...Re set the speed to 1800...Lean the low some more...The idle speed will increase...Re set the speed to 1800...Keep doing this until the speed no longer increases as you lean the low needle...With the idle at 1800 try the transition...It will probably die...Slightly richen the low needle until the transition is good...Re set the high for max rpm, back off just a little...The carb will be really close....There is a spot just above idle where the needle setting will not be so touchy, that's where you want to be...Takes a little experimenting, don't give up....
All the G26s I have converted turn about 8200 with the stock muffler and a Mejzlik 18-6, 8800 and more with less restriction...32-1 oil, 87 octane gas, 7000 feet altitude...
There is no difference in performance with electronic ignition, a spark is a spark if it's in the right place...Stock timing according to the Zenoah manual is 28 BTDC....

Magna

Hi Ralph

Thanks for the detailed explanation, I will try that.

Hi Silversurfer

Reason for me looking at the nos is because with original setting, I got 9000-9100 rpm on APC 16x6, so with 18x6W which seems to have been flown by many, mine drop to as low as 7000 before it reached 7300 when I set it back to factory, obviously still on rich side as I open extra 1/4 turn on both needle.

Even with loads, I should be high 7000, say close to 8000. I hope my case will improve from here. My tuning skill(lack of it) is seriously impeding the flow....

Antique

My Feedback: (4)

18-6 W will not turn 9000 but will turn over 8000 with less restriction...Run it some time with no muffler at all....

ryan@ddm

But not for too long, and not because of the ear-snapping sound

Extended operation without a muffler can lead to significant temperature differentials near the exhaust port of the cylinder - which can cause the cylinder to warp and crack.

Magna

Hi all

I have followed the points best I can, and this is what I get with APC 18x6W.

Start with 1.5 turn open for both needle as well as with 2 turn full open. Tuned the hi first and then the low bit by bit. Very hard to sustain at 1800 rpm idle for tuning. The hobbico meter will see it up and down from 1800 to 1900 even though I detected no change of the engine rpm sound. I then set it with 2000rpm, much easier. It got a to a point(almost there) with little sagging or hesitation if I whacked the throttle WOT. It take like .5 sec to reach full speed. It seems the sagging only happen at the very lo rpm range somewhere 2000-3500. Anything above this it responded instantaneously! If I open my throttle slower, its perfect but I felt it be better.

I tried to lean it them bit by bit and hopefully will get better result. Then I repeak the hi, it now hit 7500 rpm vs earlier at 7300.

It idle very well at 1800 or 2000 but transition is not instant if too low idle.

Then just for fun, I installed a free flow muffler that look like tuned pipe header with 1.6mm ID (except no tuned pipe) from my buddy. It was loud as crazy. Ear drum feel like bursting! Rpm went up to 8100 rpm!!! LOL!

Am I on the right track?? Thanks all!

Zippi

My Feedback: (10)

Magna,

I am getting the same thing with my G26. I'm running a XOAR 18X6 prop and the best rpm I can get is 7500. My engine also will bog down if the throttle is advanced to quickly. I have riched up both the low and high needles and it still bogs down. I tried an APC 17X6, retunnedand I was getting around 9600 rpm but it would still bog down. I am not new to gassers but this one has me a little stumped.

captinjohn

Zippi, 9600RPM,s is not bogging down!!! What is it you mean when you say "bogging down" ? If you open the engine throttle to fastthat hasa fairly big carb bore...it may bog down on spool up. Maybe it would help to adjust your throw on the throttle servo...so it opens a little slower! Just a Idea. Capt,n

Zippi

My Feedback: (10)

9600 rpm is pretty good for an APC 17X6 but that's if I ease in to it. If I stab it the engine will bog and die. I just came back in from the garage and I put the XOAR 18X6 back on and retunned it again. If I richen up the high end I get a really good fast response on the throttle but the rpm is down to about 7000. That's not good for a 26cc with an 18X6 prop. I should be getting well over 8000 rpm.

captinjohn

Zippi, i see what you mean. Maybe the 18x6 Xoar may be too much prop for the 26. I really do not know. Did you try a few degrees each way on the spark timing? Capt,n

Zippi

My Feedback: (10)

Thanks for the info Capt. The 16X8, 17X6, and 18X6 are the props of choise for a 26cc. Don't know what I'm doing when it comes to the IE other than hooking it up. This is a G26 from Ralph Cunningham and he's one of the bestwith Zenoahs.