Good afternoon everyone. I'm having a problem with an engine. I bought a super tigre g51. Now, I've been trying to tune it since last fall. My problem is, I get a good idle and and good response, but when I take it up to w.o.t. it runs for maybe 5 seconds, then dies on me. This happens almost every time. Once in a while it'll bog down and let me back off the throttle and recover it without it shutting off. I've tried two different plugs. A long plug with an idle bar, not sure of the make. A guy at the field gave it to me and told me to give it a try, and an OS8. One other thing, no matter how tight I make it, the exhaust leaks. Could that be the problem? Could it be at full throttle, there isn't enough pressure to push enough fuel to the carb? If so, how can I seal it up? Is there an oring I need? Thanks for any help.

I saw one guy out at the field screwing around with a ST with similiar problems.

Since others were helping him, I didn't think to step in.

However after I saw him fighting with the engine for DAYS, I finally stepped in.

He had the "cat eye" facing UP instead of down.

I remove the needles, flipped the cateye over, stuck the carb back in and the problem was gone much to his amazement.

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Also pull out the carb, put a CLEAN piece of fuel tubing on it, and with the the throttle wide open, blow through the tubing.

You should hear and feel an audible escape of air.

Close the throttle while doing this and air should continue to flow to a lesser degree until the barrel is completely closed.

If all else fails take the carb apart, and clean it out. I've found debris in ST carbs that affects transitions and idles.

That wouldn't solve an existing problem and could create a new problem.

BTW: Did you put in an in-line filter?

Any small debris could partially clock the cat-eye arrangement the ST's use.



Open the throttle up fully and look down the throttle barrel.

You will see a brass rectangle transversing the opening.

If the brass rectangle appears to be solid, the "cat eye" is facing down as it should.

That brass block should be perfectly perpendicular to the entrance.

If it looks good, loosen the carb screws and pull off the carb. Note or preferably mark the EXACT postion of the carb with a marker before you do or your throttle trims will be way off once it is re-installed.

Now that it is off, turn the carb over and you will see the "cat eye".

Open and close the barrel. As you do so you'll see what appears to be a pin, that moves into the cateye opening.

At mid throttle that pin should move to about 50-60% of the distance down the cat eye.

At full idle it should almost close all but 1-2 mm, but you will not be able to see this because of the barrel opening.



What do you mean by this?

Is the engine upright or inverted?

Why do you say it is leaking? Do you see smoke coming out somewhere it should not?

Is the header affixed properly to the cylinder head?

Where is it leaking from?

Ok, if you are aware of the exhaust assembly on a super tigre, there is a header that bolts to the engine, that piece slips into the muffler and a screw clamps the muffler to the header Assy. That is where its leaking. I know this because I see oil leaking from that joint. It's leaking badly. This is why I think I'm loosing too much tank pressure at full throttle.

You may not have the header tube inserted far enought into the muffler.

Loosen the holding screw and twist the muffler back and forth pushing the tube in as far as it will go, then re-tighten.

You can use high temp sealant to make a better seal, but unless you see gobs of smoke coming out of the tube, this isn't your problem.

Try to angle the muffler exit DOWN to help with the oil issue....


BTW: one thing you should check ASAP which many miss.

The pressure nipple on the muffler of ALL glow engines can and will get full of crud from time to time.

I don't know how many engine problems I've cured for people by walking up, pulling off their pressure line, sticking a small allen wrench in, reconnecting and telling them to fire up their plane again...

You may not feel resistance to inserting something to clean out the crud, but it can be there never the less, preventing your fuel tank from pressurizing properly and killing transition performance.

Ok, ill give both of them a try. I don't think its a nipple, because I put a new nipple in it when I got it. Wait, do you think the nipple isn't big enough? I mean opening wise. Maybe I need a bigger opening nipple. It was broken off when I got the engine, and the lhs gave me a replacement, I believe a dubro. I drilled the size the directions told me, and threaded it in. Wonder if I got the wrong size. I'll check into that. And try to reposition the muffler, and pull the carb off and look at the cats eye. Thanks for the help. If everythings ok, I'm gonna go the hi temp sealer route. I'll let you know how it comes out.

The tank does not require a lot of pressure, you only need about 1-2psi from the exhaust to provide adecuate pressure for the fuel.

Somehow I doubt that you got a nipple that is not the right size. If anything since you re-drilled it is likely you installed a slightly larger one.

But the nipples can fill with crud that gets blown in by the engine very quickly... even if the nipple or engine is new.

All the more so if you've been screwing around with the engine, as you may dislodge junk that has built up inside.

Check by hooking a piece of clean tubing to the nipple and blow through the clean end. (Remember though that pressure is building up inside the muffler and you may be blowing in the wrong direction so to speak, which is why I still advocate checking to make sure the opening is free of debris. )


Do the same for the carb.

You can use the same technique ( I use a small brass tube hooked to clean tubing ) for the fuel tank too.

You should be able to pressurize the tank by blowing, but the pressure will not diminish over time which indicates a leak.


Super Tigers are a bit problematic at times during transitions...

Some engines I've had are very smooth.

Others can be set to EITHER transition well but idle poorly ( too rich, they bog down ) or idle great but transition bad.

When I get one of these problematic engines ( fortunately so far I've only had two ) I use this fix...



My Gallery has the article associated with that image...

It cured my problematic SuperTigre, but I'm not sure this is what you need.

G'day

I have a ST 51 and it was just like yours. The first thing that made a big difference was a different plug. I started with an OS F (four stroke) plug, and this made the engine usable. Later I tried an Enya #3 (said by many to be the Rolls Royce of glow plugs). This made the engine perfect. That plug is still in the engine after six months occasional use.

I use fuel with 10% nitro, 5% castor oil, 15% Klotz T200 synthetic oil and 70% methanol.

Mike in Oz

K. Checked all ports for dirt, all seem to be flowing well. Ill try to seal the manifold and the carb better. I checked in the engine, and it looks almost new. Then ill try tuning it again. Oh, and maybe get the recomended plug for this engine. For all I know the idle setting could be messed up to.

Ok i think I found one of my problems. Just found tuning directions from super tigre. Tell me to open carb 2 1/2-3 turns to start tuning the carb. I was starting 1 1/2 turns out. Would explain why it was stalling out at full throttle. The engine was being starved for fuel. I'm going to seal everything up and tune this thing according to the directions, to the letter.

It's handy to have a syringe to check engine and fuel tank problems. I like to first look at the fuel tank, mainly the feed line, but the return/pressure line can cause trouble too.
You should never be able to see a parade of bubbles traveling through the feed line. If the tank and lines checks out, then I move on to the engine.

I'll check for bubbles when I get it back together and start tuning it. I did find the exhaust leak though. Took the header off to check the fitting, and there isn't a gasket between the header and the engine! I'll fit a new one on and seal everything up, then I know the engine isn't the problem.

Was the engine new or used when purchased? This brand of engine and others when run lean will eventually destroy the engine. I believe this is your problem and there is nothing that can be done so toss it and buy an OS.

How helpful.... []

it's very hard to "destroy" a SuperTigre, like that.

They simply will NOT run overly lean. If the engine starts and runs at all it tends to be close or within it's sweet spot.

I'm going to go over it, then re-tune it. Oh, and I got it used, barely. Two tanks.of fuel went thru it. Since then, I've put two tanks thru it. Thanks for the help. I'm gonna stick with it and get some hands on help as needed. It seems like a good engine, once properly tuned. I've got to get this one running, I've got a new engine comming.

I have never understood these kind of replys.?? It's like working on a ford and a member ask for some advice and you allways get the clown that says junk it and get a Chevy..............Nice reply and so helpfull.

BIGMIG [&o]

Lol. I'm a Chevy fan myself, but I see what you mean. There's one in every croud and I've found mine.

Super Tiger 51 is a ringed engine and takes a lot more time to break in but, once fully broke in it will be a good running engine

Thanks. That's what I was told when I got it. was also told to make sure I got the Italian made one as the Chinese ones are junk.

If it is a ringed ST, NEVER run it lean on the break-in, and only gradually lean the needle for full RPM over many short runs. Excess heat will destroy the ring/cylinder seal very quickly on a new engine. For the first few runs, it should be run with WOT, plug heat on and so rich that raw fuel is spitting out the exhaust. It should not be able to keep running without plug heating. You are trying to knock off all the machining dingleberries and rub in the ring and big end bearing, and anything nasty should be washed out with the exhaust. Rich also means that there is plenty of oil for lubrication and heat extraction. The engine will then thank your care and continued consideration with a long and happy life.
Evan, WB #12.

The Italian ones were certainly better, but I would not consider the Chinese ones to be "junk".

I haven't had one of the latter fail after years of hard flying 20+ minutes per flight sortees.

I've been told by several people at the field, and I believe one on here that they would never buy another Chinese made one again. Really, I don't know the difference, but I'm going off what I've been told. They may well be an acceptable engine, quality wise.