Re: Super Tigre Carb Tuning

Can you provide me some basic instructions on tuning my smaller (les
than 120 sized) SuperTigre carburetor? To properly set up your carburetor, there are a few steps...
Make sure the spraybar is set so that the fuel slot is pointed straigh down the center of the carburetor. You will have to look through th carb from the bottom, with the venturi opened to full. Loosen the tw screws next to the high-speed needle valve to rotate the spraybar s that the slot is centered.
The idle needle can be seen in the slot of the spraybar. It looks lik a piece of wire that has the end squarely cutoff. It should be less tha one-half way across the slot when the venturi is opened to full.
The high-speed needle should be opened about 2-1/2 to 3 turns out fro closed.
All of these settings are very rich. You'll have to start the engine a about 1/4 to 1/3 throttle. Once the engine starts, advance the throttl to full. You can then lean the high-speed needle until the engine i running just rich of peak RPM.
Once you have the high-speed needle set, you can retard the throttle bit and use the idle needle to adjust the engine. Retard a bit, an adjust. Keep doing this until you have reached the desired idle RPM an mixture. Remember, since we started out with an intentionally-ric setting, the idle mixture will have to be leaned.
Finally, the midrange can be adjusted by rotating the spraybar a hair Just loosen the two screws next to the high-speed needle and rotate th spraybar just a tiny bit. Either direction is OK. This will help you ge a good transition and midrange
-- bgferr ----------------------------------------------------------------------- bgferr1's Profile: http://www.rcgroups.com/forums/member.php?u#347 View this thread: http://www.rcgroups.com/forums/showthread.php?t 728
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How old is your Super Tigre engine? The older series of ST carbs tuned like a recent OS and did not need midrange adjustment of the spraybar unless you were running a tuned pipe. Sometimes not even then.
Ed Cregger

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I have around two dozen Super Tigre engines and I don't think I've ever made the famous spraybar "midrange adjustment."
I think Super Tigre's hard-to-tune reputation is undeserved and intimidates some folks.
Good flying, desmobob
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Agreed.
The problem, as I see it, is that folks plop a NIB engine on a model and expect it to be able to tune it right up and just fly. That's not how many glow engines work right out of the box. There is that necessary thing called break-in.
Many brand new engines are not reliable in idle and transition until they have had at least four or five full tanks of fuel rank through them and even then they will improve significantly over the next twenty or so tanks of fuel and will require retuning now and then.
Then to further exacerbate the "problem", folks fit the engine with a 12" low pitched propeller, which compounds the problem and makes an engine that is designed to run on 10" props struggle with swinging a huge windmill. Super Tigres were designed to rev up. The standard prop for a .40 to .45 back when these engines were designed was a 10x6 or 7, NOT an 11x6 or a 12x4 - 5.
Wanna make it even worse? Use fuel with 15% or more nitromethane. Suddenly we have a midrange that is too rich, so what do we do? We use an OS Type F glow plug which ratchets up the problem even more.
OS Engines has followed these usage trends by designing engines with extra large cooling fins and more of them. The result is that these engines will tolerate larger propellers and greater amounts of nitro without a problem. To even make it better yet, their machining specs are so much tighter that their engines really do not need an old fashioned break-in. Just the token break-in described in the instructions.
Gee, now I feel better that I have a couple of OS .55AX engines. Maybe, after completing a few sales and swaps to help clean out the garage, I'll be able to resurrect my Fun One and plop one of the .55AXs on the Edson Universal Adjustable Engine Mount that I bought from MECOA/RJL a short while ago.
Ed Cregger
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replying to Robert Scott, Larry Stahl wrote: Might you also repair these engines? I have one SuperTigre 40, made in Italy, in original box - I think it was crashed. There is a label that reads: "S 40 ABC W/M" and below is written: "cod. 11001824". I know nothing about this engine, except it appears to be very well made. So, anything you can tell me is appreciated. Thank you.
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It's a new GS 40 made in China not Italy. The info on my previous post is straight from the FAQ section of the Super Tigre website. I have yet to try it, but I will soon as I am having issues on the transition from idle to wot.
--
bgferr1
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Fit it with a 10x6 prop and burn fuel with no more than 10% nitro.
Run four or five tanks of fuel through it on the ground, but elevated three feet, very rich to seat the ring. Keep running the 10x6 or even a 9x6 or 7 sized prop. Don't fall for the 11x6 thing that folks will tell you to use. The Super Tigre .40 was designed in an era of high revving engines - noise be damned. If you try to lug them down with a large prop, you will experienced a rich midrange, even after break-in is complete.
The GS-40 is a great engine. Congratulations. There is nothing wrong with the carb.
Ed Cregger
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There is a premium plug from Enya that solved the midrange barbling when accelerating from idle to takeoff. After dinking (n optional) around with two ST51's from the 90's I found the extra buck or two for the premium plug to be the permanent fix. Went from deadstick dog to reliable.
Frank Bowman, a piston ring fitting guy who I no longer seem to be able to contact, clearly stated to me in an email that he religiously laps the liner tops on Super tiger liners that he is fitting rings to. He said that they are notorious for not being flat enough to seal properly at first. Perhaps the "extended break in" is the period of time to gum up the leaky head? I've seen more than one exhibit "mystery" drops of fuel and oil coming off near the head gasket level.
But the Enya #3 has higher platinum content- most of our "platinum" filaments in glow plugs are a sponge impregnated with a little platinum. The platinum is the magic which catalyzes the glow fuel to "compression ignite". One theory for why the enya 3 works so well is that it has more platinum for much longer. Sure they're $6 instead of $4, but mine all last for years.
--
Waterbug
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replying to Robert Scott, Larry Stahl wrote: Might you also repair these engines? I have one SuperTigre 40, made in Italy, in original box - I think it was crashed. There is a label that reads: "S 40 ABC W/M" and below is written: "cod. 11001824". I know nothing about this engine, except it appears to be very well made. So, anything you can tell me is appreciated. Thank you.
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