Hope this is the right forum. The problem I am having is the engine, after about 3 tanks of breaking in, still cuts-out when throttling back and has a hesitation when accelerating. Any ideas? Also, I misplaced the manual for this and cannot seem to locate one anywhere on the net. I've read several posts, but the all are too vague. Some one out there I'm sure has experienced this same problem....please help...[:-]

I have one and it took a bit of time playing with the needles before I got it running right. I used an engine test stand and ran the engine until I got the low end needle right. Then I started playing with the high end, running it first on the rich side and then slowly leaning it out. As I did this process I had to make a few adjustments to the low end. I noticed on mine that the low end adjustments had to be made in small increments. And the high end seemed to have a sweet spot and if I got away from the sweet spot, it did not run reliably. So, keep trying to tune the engine with small adjustments. Once you get is just right, leave it be.

JR

I've had 4 of these and you have to make sure the idle mixture setting(little screw on the side of the carb)has about a 1/8 of an inch gap in the mixture screw with a wide open throtle,all of the ones I got had different settings when I got them and this seemed to afect low end if not set right with the sputtering tour talking about.lol

OK, I have lost my manual and everyone is saying adhust the low end to a certain mm gap...where do I measure the gap...or even better, about how many turns out is it roughly?? For the low end that is?? And which one first, low or high end....It seems this engine runs fine for a while, then I can't even get it to start and raw fuel is dumping out. THANKS for the input guys and please keep the info coming...

IN reply to the 1/8 gap, where is that measured??

As you look down the venturi from the front of the engine, you will see a needle protruding from the left side, and a spray bar from the right side. You want this 1/8" gap between the two when at full throttle. If not, adjust the low end. The low end adjustment is the small slotted screw on the left side of the carb (looking from the front). This screw will adjust the needle that you were looking at in the venturi. Turn the screw CW to close the gap (leaner), or turn it CCW to increase the gap (richer).

While I do not own a TH 46, a 1/8" gap seems a bit excessive to me. Another method to initially make this adjustment is to attach fuel line to the carb's input nipple and blow into the fuel line. Make the low end adjustment so that you just start to hear the air coming out of the spray bar.

Good Luck and holler if you need help.

I have the same problem with mine. Since I have it on a SPAD3D, I tune it with the airplane vertical to be sure it won't lean out and die in a hover. The problem with that is it loads up when horizontal. Very frustrating indeed, wish I would have bought another FX.

1/8 inch gap is what it calls for in the manual and I always start there and do a little adjusting from there if needed,I have as well as a freind of mine,have had to just send them back in,but the ones that I have now run just as strong as an fx,any day!not dogging o.s. cause I've had them to,but I like the tower engines and think they run great once dialed in,and if your a tower memeber,you get a 4 year waranty!can't beat that. Oh,ya and I bet if you call tower and tell them you lost your manual,they would probaly send you a new one.lol

On the hesistation in the throttle is it in the midrange? If it is it could be from using an idle bar plug in this baby. Mine acted up like this until I put a non idle bar plug like the OS A3 or Tower Power plug back into it. On the bottom it just sounds like you need to tune the low speed needle. Good luck.

Sport10

Mine runs fine w/o an idle bar. It has a cheap TH plug in it.

When an engine HESITATES its tuned to LEAN (not getting enough fuel). When it STUMBLES it's too RICH (getting too much fuel).

Try this... Set the low speed RICH so its operation doesn't intefer with the high speed adjustment (1/8 inch as stated before). Tune the high speed for max rpm then richen it a few clicks (ccw on main needle). (This is because in flight and as fuel levels in the tank decrease (lower) which will cause the engine to lean. A lean engine runs too hot and this will damage you engine.)

Then set your low speed needle. Test it by letting the engine idle a bit (5-15 seconds) then opening the throttle. If it hesitates or dies then it's too lean (open ccw on the low speed). If it stumbles and smokes then it rich. The low speed needle is very sensitive to movement so only 1/8 or smaller turns as necessary. As you get close a 1/64th turn are in order. Once you get the hang of it - it's quite simple and you'll be able to do it in a minutes. Also, a tachometer is better for setting the high speed but max rpm can can be done by listening to the engines pitch. But, be careful to stay a little rich on top (high speed needle)...

Don't fly your airplane until everything is perfect on the ground. Otherwise your risking your investment. As your flying it listen to the engine. An engine in the air has a different amount of load on it. Therefore, your fuel mixture will change slighly.

I have the Tower instructions - they are too big to scan in totality, but if you need the section on tuning just email me. I can't post them as they have a copyright notice on them.

There are other methods but this is what works for me. There was some mention in other posts about transition. If your asking about setting the needles your problem is most likely not a transistion problem. A transistion problem is when you get the high and low speed needles set perfectly but the engine won't run well in mid rpm. My experience with this engine leads me to beleive that once you get the needles set it should transistion fine. Mine has a good carb. on it. I noticed two break-in points. At about 2 tank fulls it ran smooth and then after a gallon it got smoother. Now it ticks over like a Swiss Watch...

I have one of these engines also (what a bear to tune), you also may want to check for air leaks around your needle valve assembly. After countless days of adjusting this so sensitive engine I pulled my lines off of the needle valve (both inlet and outlet) and put a scrap piece of line on one side and held my finger over the other and blew. Guess what ? I could hear an air leak . It wasn't the needle its self but it was leaking around the two orange gaskets. I disassembled it and used high temp RTV to seal the threads, I have no air leaks and the engine is not near as finicky. Just a thought you may want to try, this engine seems to make a lot of power.
Good luck

Turn the idle screw in 1/4 turn, and see if it improves.

My friend who flies with three others that have these engines, gave me a restrictor(well, kind of), that goes in the exhaust pipe. He said this helped greatly with his problem, so we'll have to see. I'll try it later today. Thanks again for all the replies.

Well,as far as the exauhst goes,my buddy said he has heard of someone else doing this with a sleeve that fit inside the exauhst because they where not geting enough pressure to pressurize the fuel tank,but if it goes beyond that,and still doesn't run right,send it back for warranty repairs,but let us know the out come. Andy

You got it....charging the reciever battery right now...will know something soon...

Well, I flew my P-51 foam fuse/foam wing, Tower Hobbies .46, and despite all the problems with that engine, she flew GREAT!!! I put a restrictor in the exhaust and that was the ticket. Now it transitions beautifully and doesn't stall when idling down. I had a 'professional' fly it...since I've never flown a low wing performance plane. I told him to ring it out and thats exactly what he did. He said it's one of the best flying planes he'd ever flown..but, he also said it was ugly...in jest. The motor ran flawlessly. Now, I can't wait to go fly her myself. A BIG thank-you to all who helped me.

Glad this worked out for youI'm definitly going to remember this one with the TH .46 I might have to try this with my TH .61 I have in my shoestring,it just doesn't seem to top out all the way,and thought it was not getting enough fuel,mabey this is my ticket! lol flying

I have had 2 of these, and the same problem. What they need is an extended break in period. Also, as mentioned earlyer, make sure everything is right on the groud before flying it. They really are good engines, you just need a little patience.