In another post, it appears that this carb may be a butterfly design.

I just don't think the small displacement is able to be carbureted properly with gasoline. The passage size and needle taper for reliable tuning might be out of reach?

It goes back to what others have said about linear fuel delivery. You might get it right, but it's probably dumb luck.

I'm of the opinion that the difference between the venturi effect at idle vs. WOT is too great to rely on the ports you can make available on a carb that is small enough to fit on these units.

I hate the GT9 I have, but I cannot dispute the fact that it is an absolute animal at WOT on either gas or glow.

Sorry but I cannot agree. Brutus has shown it is not difficult to get acceptable fuel delivery and throttling from small gas engines. I have a NGH GT9 too with a cheap ASP carb and a muffler from Just Engines and it is fine. With a Graupner 11x6 prop it idles at 2,800 rpm and 9,900 to 10,100 at WOT depending on the air temp. The muffler (from an ASP .40) does make a difference.

"Not difficult" is pretty subjective. There's just a hand full of us that would attempt to make those mods, let alone dedicate the time necessary to get that all figured out. Also, I don't think anyone is arguing the engines don't make power. They do! The 10cc Evo will turn a 13x6 to 10.5k pretty easily.

The bigger issue, the one Tucci mentions and I agree with, is to date the production 10cc engines have fuel calibration issues, big time. They idle, and they have great top end. Mid range though, is pretty miserable when it comes to consistency and flat spots. In fairness, I have to say it would appear we have a new generation of carbs to play with that are just now coming out. My fingers are crossed, but only time will tell if they finally got it right with these. -Al

"Not Difficult" indeed is subjective.
I have recently found out some things about myself and psychology in general (long story but it involves the Kruger-Dunning effect), so I go along with it being a bit more difficult than I personally estimate.

That does not do anything to the fact that I am just free-hand grinding away in a standard glow carb, and still getting it right now 3 out of three and a fourth underway.

Effectively that means, that it might not be easy for Joe Average, but it should be absolutely doable for a manufacturer with an R&D budget and facilities. Plain and simple.

Left or right, difficult or not, it is possible and a manufacturer should with certainty get better results than me.

As for calibration and small engines: I am on my way getting a 5 cc (.30) fourstroke done, and I do not have the feeling it is impossible.

If I can do it freehand, imagine what I (or any manufacturers "local guru") could do having a proper R&D workshop....

Well I doubt the Chinese have gotten very creative or imaginative yet. They still just blindly copy what is out there already. Unfortunately, their improvements tend to be badly thought out or done.

My experience with the Chinese mfgr's has been that if they can't get it right on paper, there's no way on God's earth they're going to get it right, period!

Oh, and I agree Burt, this is not an insurmountable problem. It should (could) have been fixed a long time ago.

Where is Mr NGH ? He is pretty quick to post pics of his new 9cc engine but has never come on here to explain its issues . Selective deafness I guess.

Originally Posted by the pope

Where is Mr NGH ? He is pretty quick to post pics of his new 9cc engine but has never come on here to explain its issues . Selective deafness I guess.

The original lead engineer left the company. He went off to do different things. Whether he left in good graces or not is questionable.

Yeh didnt he go off to JBA amongst others ? I think he leaves a tale of woe wherever he went . Im sure Mr NGH must have some knowledge on the carb issues that us mere mortals dont know and would like to .

Originally Posted by the pope

Yeh didnt he go off to JBA amongst others ? I think he leaves a tale of woe wherever he went . Im sure Mr NGH must have some knowledge on the carb issues that us mere mortals dont know and would like to .

I think you have some facts right but timelines wrong, but hey who cares if you "share your love" and if it makes a good story?? ...
I Think Mr. Chow started with JBA where he designed the JBA 15G (small issues with the large carb and muffler but nice engine otherwise), afterwards he moved to NGH and designed some of the NGH engines. He also converted the JBA 56AR to the NGH GT9.

I have finally fitted my ngh 9 in a ben buckle falcon, all 96" w/s . With a bolly 12.5x6 and an 8 ounce tank running times in the order of 45 minutes.
If you fly vintage/old timers you'll appreciate that that the throttle is either all or f*** all, this thing keeps the plane up on just over tickover.
I've fitted an OS 46 fx super silencer on it and the only way to hear the engine is to rev up when it's flying.
I slowed down the servo to the throttle, now takes about 1.5 seconds or so to go from idle to full throttle.
It's not perfect but it keeps me happy.

That is looking nice. I think it all turned out well for you too.

Originally Posted by ngh engine

NGH GT9-Pro

now in stock from HK. very cheap with CDI https://hobbyking.com/en_us/ngh-gt9-...___store=en_us

Dang! I can't convert an equivalent glow engine for that kind of money...

Now it still has to prove itself, I guess, and I am still not convinced about the long term reliability of all these membranes and thingamagoogles in that carb....