Thunder Tiger 1.20 Problem....Help!!
 

One of my twins has a single fuel tank in the main fuselage, no header tanks in the nacelles. Both engines have Perry pumps. Beautiful. Highly recommended.

A single engined plane is flying in vain.

WLR

Thunder Tiger 1.20 Problem....Help!!
 

MarkR, my TT 120RP runs beautifully on 5% nitro 10/10 castor/synthetic, so I don't see any problem with 5% nitro 20% castor, other than the fact that the lower the nitro percentage, the more sensitive the needle valve setting is going to be. That's just the nature of the beast.

The head shims are not always necessary, especially if you run with little or no nitro. I would suggest running it with no pump first and get it to tune properly. All else being properly set up (e.g., tank position etc.), a misbehaving engine is not going to improve it's manner with a pump.

Thunder Tiger 1.20 Problem....Help!!
 

Volfy:

Si vis pacem, para bellum

Agreed. Also:

Semper paratus.

WLR

Thunder Tiger 1.20 Problem....Help!!
 

....Hey ...you guys really surprise me with the 5 % fuel talk. You are talking about a 1.20 here not a .25....!! If you want performance..15 % nitro is the call.... otherwise settle for average at the very least !!!! Try it .... you'll know what I'm talkin about !!!!!!
Alan

Thunder Tiger 1.20 Problem....Help!!
 

Alan, my experiences has been that the little engines are the ones that needs the extra nitro. The Cox .049 and such really wake up with 30% nitro. The small engines have much more heat discipating surface area with respect their displacement so they can use the extra heat generated by high nitro and actually prefer it.

The big glow engines, however, can retain combustion heat much better and can run happily on little or no nitro. Mokis, for example, run great on FAI fuel. That's not to say they don't make more power on more nitro. With head shims in place, you can safely run the big boys on higher nitro too.

I personally prefer to run my bigger glow engines on low nitro for better fuel economy. It's nice to get that extra power with higher nitro, but fuel consumption goes up too. That may not be a big deal with a .40 engine, but on a 1.20 or a 1.50 2stroke, that could mean carrry 24 Oz. of fuel instead of 16 Oz. for the same flight time.

Thunder Tiger 1.20 Problem....Help!!
 

Volfy, I generally run everything on 15%, but not for the power. All the way down to the Cox 0.020 on my "Littleist Stick, " up to "Iron Annie the Saito" on my Ultrastick 120, my engines run well at 15%, so I only need to keep one type on hand. I use Omega 15% heli, gives the lube needed in everything, the big 4-strokes are happy and the little Coxes sing.

(But the Zenoah G-38 really prefers a gas/oil mix.)

Want to sing? Put a twin on the wing!

WLR

TT120 sorted
 

Just an update on the earlier problems with the TT120 - I sent it back to the supplier after some more messing about. After a liner and piston change, it now runs spot on. Vertical performance is excellent.

Thanks for all the replies to the original note. :)

TT 120
 

Azcat

I have the TT 120 and mayby three tanks of fuel through it. I need some suggestions. Here are the questions.

1. Runs very rich but very consistent. Smooth transistion long low idle speed does not seem to load up, but when you pinch test it is running very rich. Also the high end seem to be about 1 1/2 out on the needle. Another 1/4 is to rich the other way same amount to lean, but the engine is not opening up tach about 6200 on a 16x6.
2. Compression seems low on this engine do they take a while to break in?
3. Fuel flows out the inlet to the carb hose if I take it off the carb nipple. Do I need less muffler pressure.

This engine is smooth and seems reliable but running at about 1/2 power.
Any suggestions ??? :confused:

Thunder Tiger 1.20 Problem....Help!!
 

The compression on my first one was terrible, and I thought it would get better with some bench break-in. Half a gallon later it was still poor. I sent it to ACE. They claimed they put in a new head gasket, and that compression was fine. They seemed to kinda, maybe, think so, that it could have an expanding ring, and seemed to have not heard of a Dykes ring. Mine is still very low on compression, have to use a starter to start it, but it produces some serious power in the air. Last tached at 8800 with 10% Omega, APC 16x8, and a Slimline Pitts style muffler. I have engine number two now, but have not yet run it.

You might be well advised to send it in to the importer, ACE, and have them check it out.

I haven't flown the Edge 540 it is on since December so don't remember where the needle valve was, but around 1 1/2 to 2 turns open, using a Perry Pump.

Good luck with it.

Clair

Thunder Tiger 1.20 Problem....Help!!
 

Thanks Azcat

I will try a few more tanks through it but if I dont get serious improvment I will send it in. Probably after a gallon. I think I will put the 16x8 on it also. Gee my .60 has more compression than this. I did get on the Ace web site but you cant e-mail them with a question (thanks a lot). So weather permitting I should know by next week if any improvment. By the way how many turns out are you on your high end needle?

Thunder Tiger 1.20 Problem....Help!!
 

See above re: turns out on high speed needle.....somewhere around 1 1/2 to 2 turns open as I recall. Start with two or more and then turn it in until it sounds right.

I agree with your distaste about customer service at ACE since they moved to California. Hard to get any straight answers from them. The guys across town selling Chinese Magnums are apt to eat their lunch if they don't wake up....

Clair

Thunder Tiger 1.20 Problem....Help!!
 

AZCAT

I flew three more tanks through it compression is still week but it runs great. You couldn't ask for a smoother idle or transition. It was that way out of the box but the high end seems rich. I would really like to get more than 6200 on a 16x6 prop at sea level. Someone mentioned head gaskets? Anyway it pulls my 10.5lb Balsa Nova but barely hovers it.

Thunder Tiger 1.20 Problem....Help!!
 

Mine would probably windmill on a fast dead-stick...so little compression it is hard to tell when the piston is starting up, but the engine runs strong.

Your 16x6 rpm reading sure sounds low, especially at sea level. Have you taken a reading with another tach? Maybe your tach is off. Mine turned a 16x8 APC 8000 when new still on the bench, and after break-in, 8800 with readings from two tachs. 10% fuel.

Clair

Compression...or lack thereof
 

Don't worry about the lack of compression on these engines. The ring is designed to expand when the engine fires to seal up the chamber (according to our local engine guru).

At first I was concerned about the lack of compression on my TT120 even though the engine ran quite strong. When I pulled my new one out of the box and found that it had very little compression just like my other one, I figgered that was the nature of the beast. And what a beast it is! There's just enough compression to allow starting with a back-flip of the prop, but only after the engine is warmed up.

I'm still running mine on 10% nitro with a VP-30 pump. After leaning out the low-end needle a bit more the midrange stutter all but disappeared. The engine runs great and will easily pull my WM Extra 300 1.20 out of a hover. I probably have 3 gallons of fuel through the engine, and have heard that it takes 5 gallons before they're fully broken-in. Definitely one of my favorite glow engines.

-Tom