Thunder Tiger FS75 problem in Reactor 46
 

Have a new TT 75 in a reactor 46 (Have about 3 tanks thru it). Last time at the field engine would run up on the ground but would not go to full power in the air. Took it apart and reworked fuel lines and retuned engine statically (including low speed), seemed to be running fine on the ground. Good idle, great throttle response. Put it in the air and it ran fine for about 3 minutes and then would not go to full power again. Landed and tried to adjust it on ground but it stalled and would not restart at all. It was pretty windy so we packed it in for today.

I am beginning to think it may be overheating, the Reactor has a pretty tight cowl but we have cut good sized entry and exit vents.

Fuel tank may be just a touch high since the TT is mounted upside down. Only other thing to note is that it has a dubro fueling valve mounted in the side of the plane. We are using Cool max 15% nitro fuel with 18% synthetic lubricant.

Any ideas of what we are missing?? I am thinking about returning it is this keeps up.

Thanks Bill

RE: Thunder Tiger FS75 problem in Reactor 46
 

Try it without the cowl and eliminate the question about it getting hot

RE: Thunder Tiger FS75 problem in Reactor 46
 

what you need to do is go back to basics with the set up of fuel tank etc etc. start by making sure the fuel tank internal lines are correct in terms of clunk to carby and breather to pipe , block off the 3rd line if fitted. check to make sure the fuel tank rubber stopper is fitted well with no leaks when pressure is applied. [ do this test by blocking one outlet pipe and blowing in the other ] the tank must blow out abit like a balloon would. try another batch of fuel mixed at 20% oil [ not 18% ] adjust the required carby settings as listed in your manual [ keep the high speed needle richer ] now as long as the front air intake on cowl lets air to the cylinder / head and air can escape oput somewhere all should be fine. also see if you can get the tank down abit lower as if its too high the engine will flood.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Thanks for the inputs. I was reading another 4 stroke thread and came upon another potential problem. The Reactor design does NOT call for foam around the fuel tank at all and this is the way my son built it. The tank is held in place by the neck (where it goes thru the firewall) and glued balsa in the rear. In the saito post, builders were in strong agreement that the tank should NEVER touch the wood of the plane. Any comments about how this would effect the Thunder tiger 75 in the Reactor?

Thanks
Bill

RE: Thunder Tiger FS75 problem in Reactor 46
 

The problem doesn't seems to be neither with your engine nor fuel....because you say it stops working after 3 minutes....the problem should be with the fuel delivery system somewhere....check that the clunk on the tank is working freely...when you install it again, wrap it in rubberfoam...
The engine maybe is not fully broken in...I suggest that you run a couple of tanks more, a little bit rich...and fly it a little bit rich....does the engine works for more than 3 minutes on the ground?
What kind of propeller are you using?

Saludos,

Jorge

RE: Thunder Tiger FS75 problem in Reactor 46
 

Hi jorge,

Yes the engine seems to run good in the driveway. We thought it was ready to go until we put it in the air. It has a 13x6 prop on it now but we used a 12x6 for the early break-in tanks.

RE: Thunder Tiger FS75 problem in Reactor 46
 

I don't use much foam around my tanks. No problems yet.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Fear, I have a Reactor with a Saito .82, and just used foam stuffed in back of the tank instead of the piece of balsa they call for. Haven't seemed to have any problems relating to fuel foaming at this point. Keep us posted on your TT75; I was really interested in using that engine in this plane before I found my Saito on ebay. I'm still thinking of buying the TT75 for my Phoenix Super Decathlon.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Just to keep everyone updated, we have pullled the TT 75 out of the Reactor and my son is buying a brand new Saito 82. He is tired of messing with the TT and just wants to fly the plane. We never could get the thunder tiger to run consistently at full power, it idles great. We sent it back to ACE hobby and they are going to see if they can find anything wrong with it. Will keep you advised.

RE: Thunder Tiger FS75 problem in Reactor 46
 

As I suspected, ACE hobby found nothing wrong with the thunder Tiger 75 engine except that they felt the low speed was set too lean.  They tested it upright on their stand with a smaller prop (11x8) and said it ran great at all throttle settings.  i will mess with it again when it comes back, we may put in on an extra 300 we have in 90 degree orientation or we may sell it. 

My son has the new Saito 82 mounted on the plane and is getting ready to fly it.  Can anyone recommend the best prop for the 82 on the reactor 46.  he likes to fly mostly 3D.  He has a 13x6 on it now but the manual calls for larger props/pitch.

Thanks

RE: Thunder Tiger FS75 problem in Reactor 46
 

I would wrap the tank with foam and balance your prop, both at the tips and the hub.Try flying it without a spinner also.

I would guess that your engine is going lean in flight.Is the engine real hot when you land?

RE: Thunder Tiger FS75 problem in Reactor 46
 

yes, the thunder tiger was hot any time we ran it. Now they are suggesting that the prop was too big even though it is recommended in the manual. We just ran the Saito 82 on the plane and you can hold your hand on the bottom of the engine, much cooler.

RE: Thunder Tiger FS75 problem in Reactor 46
 

I have several 4-strokes including 4 different 70-class engines, TT .75, Saito .72, OS .70 & Magnum .70. All run about the same for me. My TT .75 is in a cowled plane and the previous plane it was in had a cowl. I did run nearly a gallon of fuel through it for break-in. I found a 13-6 APC was turning right at 10,000 rpm, so I fly a 13-7 or 14-6 prop to keep the rpm lower.

I run Omega 10% or 15% castor blend fuel.

Your problem sounds like fuel foaming or the tank too low and the engine set too lean with a prop too small.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Maybe it's likely that the same problem could be reproduced by the new engine in place??

RE: Thunder Tiger FS75 problem in Reactor 46
 

thanks all for your suggestions. After receiving the TT FS75 back from ACE hobby I put it back on the test stand in the driveway. Mounted it at 90degress and it ran great with both a 12x7 and 13x6 prop. As ACE suggested to me, this engine with its updraft carb just does not like to be mounted inverted. Also seems to run better and slightly cooler with higher nitro content fuel. Thanks again!

RE: Thunder Tiger FS75 problem in Reactor 46
 

Glad to hear that<div></div><div>I'm close to reach a 6 liters of fuel through the engine, and every time I like it more and more.</div><div></div><div>I'm not sure if the engine doesn't like 5% nitro fuel, or was just not the time to do it, I couldn't get a reliable idle with coolpower 5%...so I keep with my Graupner 12% nitro fuel... it is a shame because the engien seemed to have more power on the coolpower than with the Titan G12...but because of the Idle....</div><div></div><div>Next time I'll try to finde Omega 10-15%..if the prices here allow me... and try to sell the coolpower gallon to someone...


Saludos,

Jorge

</div><div></div><div></div><div></div><div>Saludos</div>

RE: Thunder Tiger FS75 problem in Reactor 46
 

I see in post #1 you said it had a dubro fueling valve, a guy at our feild had a similar problem, engine would run fine on the ground but would act up in the air, turns out the valve was the problem, once removed it ran fine. Maybe that why on your test stand it ran great, just a thought.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Also, my engine is 135 degrees, almost inverted....I haven't had any problems with this setup so far, more than it is dificult tu start because I can't prime the engine as it is cowled, gotta get a choke valve...<div>
</div><div>I don't use anything special, normal fuel tank, fuel filter and a filling line.</div><div>
</div><div>Keep us updated on how this beaty works for you..</div><div>
</div><div>Saludos,</div><div>
</div><div>Jorge</div>

RE: Thunder Tiger FS75 problem in Reactor 46
 

Sure sounds like fuel foaming to me. The more air in the tank the easier for the foam to develop. Definitely insulate the tank, even with the Saito.

RE: Thunder Tiger FS75 problem in Reactor 46
 

A hotter plug may help the idle on 5%. IMO the Thunderbolt four cycle plugs are about the hottest four cycle plug out there.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Ok, now my TT-75s story, I bought this engine on December 2008, and here is were my problems start:

1.- Great price I would save almost $100 over a Saito or O.S.
2.- Receive my engine and the threads on the head where the exhaust manifold screw in were mismachinne manifold would not screw in.
3.- Send the engine to ACE for repair or replacement ($20).
4.- Month and a half later receive my engine.
5.- Fought a couple more months trying to get a relaiable running engine, went from a 13x6, 12x6 and a 12x8 but still something is wrong the engine out of the sudden surges.
6.- One more time send the engine to ACE for repair ($20) and of course nothing is wrong with the engine.
7.- So I start taking the engine apart by myself and what I found that the carb and the carb manifold don't seat flush with each other.
8.- ACE said that is no problem at all, but wait here comes the best part.
9.- The rubber O-Ring that seals the union is score and ACE said they check it and it was fine when the engine left their repair shop.
10.- So guest who has to pay for a new o-ring plus shipping ($10), you got it me.

And now I'm reading these engines may develop an early bearing wear, I guest at some point send it again to ACE ($20 again); sorry guys I might have a lemon but Saito or O.S. would caught these kind of problems from the begining or replace the engine. What a bargain ah, also the fuel consumption is horrible. All these 6 years runing Saito and O.S. I grew up used to have dependable 4 strokes from the get go when I opened the box, I like to fiddle with and engine from time to time but this was a nightnare, all that time wasted trying to tune an engine that was manufactured with lower standars than those I'm used to.

These has been my Thunder Tiger expirience, and sincerly hope yours are smoother than mine.

RE: Thunder Tiger FS75 problem in Reactor 46
 

jucava,

I have heard of the same types of problems with service from other makes hobby services. I don't know what the problem with your engine is but the manifold carb mismatch is common to a lot of four stroke engines and is likely not your problem. I don't know why you paid $10 for an o ring, you can buy them at automobile parts stores for pennies or at least no more than a couple of bucks. I think you need to expain the problem better because I have no idea what is wrong with it.

RE: Thunder Tiger FS75 problem in Reactor 46
 

Other manufactures services centers have done the right thing and their turn arround time has been 2 weeks at most, I was extremly explicitd and elaborated a lot my engine behavior to ACE in writng when I sended the engine.
Don't you think they should check the o-ring?
How you know if the o-ring you get on the auto parts store resitst GLOW fuel?
And no, the manifold-carb mismatch is not a common problem in other quality brands
And if you pay attencion when you read my post will realize I don't have a problem anymore only a lemon that became a lime.

I'm sorry but I just get used to quality engines that work flawlessly from the begining, even if a have to pay more, lesson leraned (save on the penny and spend on the dollar).

RE: Thunder Tiger FS75 problem in Reactor 46
 

if the o-ring from autostore doesn't resist glow fuel, than it would be just a couple of cents...

I'm not an expert there, but guys here use whatever o-ring that fits, and I haven't read about problems caused by glow fuel on the o-rings... mostly are problems with silicone diaphragms but not with glow fuel but with poetroleum based components.

This engine has a slight angle mismatch on the carb/manifold...the mismatch is an angle mismatch, and it is less than a milimeter, I can live with it, and in my engine, it is not a problem, it doesn't leaks and it isn't a problem.

I don't mind tweaking with the engines, in fact, I like it, and I really love that everytime I do something on it, the engine performs better. Everytime I have a problem, I learn a lot, in fact, thats why I like the hobby, and I like the hobby mostly because of the engines...but it is just my point of view.

Indeed I have found a couple of things problematic with the engines, and I've corrected them.

Anyway you could get a lemon with every brand.

By the way, with a thunder Tiger 4 stroke, or with other cheaper engines, I think you save more than pennys.

Saludos,

Jorge

RE: Thunder Tiger FS75 problem in Reactor 46
 

Sometimes they do the wrong thing and take longer and sometimes they don't fix the problem, I have heard horror stories from all of them from time to time. Though ACE does take a couple of weeks longer than most.

If there is no air leak there is no reason to remove the carb and check it. Pro's know its best not to take apart something that is working. A score does not mean it was leaking, in fact it could have been scored on disassembly.

Ah, but it has shown to be very common, especially with Magnum. In fact it has some benficial gain in providing turbulance and atomization of fuel. There is often a mismatch between the head and manifold as well, though I am not sure there is any advantage there.

You still have a problem, you just decided not to deal with it.

All of my TT engines have had equal quality to my OS engines except for a tendancy toward loose screws. I agree the hobby services are worse. My TT .91 FS worked better than my OS .91 FS except that it needed a longer break in. I suspect (because you have not told us what the problem was) that your problem was something else. It may have been a fuel system problem, such as a leakey fuel line or tank, or it needed more break in time, or you simply didn't understand some differance in that engine and the engines you had before. In fact I think this has been the first negative report I have seen on that engine.