[] We are new to r/c planes and have purchased two Tower Hobbies 40MKII Trainers. We are having trouble with the engine, which is a .46 Tower Hobbies two stroke. Idling is the problem. We can make the engine run fine at full throttle and at half throttle, but when we bring it back to idle to land the engine dies! Creating an awful lot of dead-stick landings. We are running 15% Omega fuel and have a Tower Hobbie glow plug in the engine. The idle mixture needle is set to manufacturer's specs and the high speed mixture is three to four hundred rpm off of peak. Curious about a hotter glow plug or maybe 30% fuel. Open to any suggestions. Thanks!!

The Tower Trainers are a very fine Trainer Plane, but those Tower .46 engines are the absolute worst! I have owned two Tower .46 engines and both were horrible. They produce good power, but are the most aggrivating engine I have ever had to keep in tune. I have around a dozen flying Airplanes with various different 2 stroke and 4 stroke engines, and I have plenty enough experience in tuning an engine. I found the Tower ,46 more headache than it was worth. A cheap little O.S .46 la would be a much more dependable engine to have mounted on that Tower Trainer, or a Thunder Tiger Pro .46 if you want a quallity engine that can move on to other planes later down the road. Actually just about any other .46 size engine from just about any other manufacturer will be a better engine than the Tower .46 IMO.

Someone will probally come in here, and tell you that you need to try this and try that with it, but please listen to all the bad experiences with the .46 Tower and get rid of that thing before it causes many more deadsticks and a potential crash!

The Tower 46 is a bit finicky at first. It really doesnt
run that well until broken in. And break in takes a while.

My experience has been that you need a fairly rich setting
on the high speed needle and a fairly lean setting on the idle.
The needles interact somewhat so expect to do some tweaking.

More nitro is not the answer. In fact this motor seems to prefer
lower nitro. And I did not have good luck at all with the Tower
plugs. They are supposed to be the same as an OS 8 but the
46 we had did not like them at all. We had much better results
with a Fox idle bar plug.

This engine leans out a LOT in the air. So you need to have
it running pretty rich on the ground. 300 or 400 off peak is
probably not rich enough. Dont expect much until you get
a gallon or so through it. I would recommend some bench running.

Mike Hammer

The low speed mixture is too rich (how do I know? -- it would be a pain to start & it would die away at part throttle if it was too lean).

Start leaning the low speed needle (turn it clockwise) 1/8 turn at a time, with testing between tweaks.

Let it idle for at least a minute after tweaking the needle, then accelerate to full throttle & reset the high-speed needle (do it each tweak). If it staggers & stumbles when you advance the throttle, it is still too rich -- tweak it again 1/8 turn. If it staggers to a stop try advancing from idle with the glo-stick on -- if that helps, it is too rich --- tweak away pal.

If it quits cold when you advance the throttle -- put the glo-stick back on & try it again -- if it still quits cold, it is too lean -- go back anti-clockwise) 1/8 turn & try again.

It is a powerfull pain in the *****, but eventually you will learn to get it close to being civilized. I hate mine, but it it is still usefull.

Thanks guys,will process the information, try to make a rational decision either tweek and keep or tweek and throw

I've had three of those engines and they ran perfect. The only problem I had was the muffler coming apart on the first one.

Enjoy,

Jim

I'm of the exact same opinion as ckangaroo70 . I've had two tower .46's, the first one died a premature death when the entire piston cracked down the side. It hadn't completely come apart, but it wouldn't run reliably so I tore it apart and found the crack. Tower replaced it, although they were nice enough to include a note saying although it wasn't due to a manufacturing defect or anything under their control, they were still fixing it. (this engine had maybe 3 runs on it, was still being broke in)

anyway, engine #2 was a horrible @#)(*% to tune. It would seem like once you had it tuned, it would hold it for a couple minutes if even, and then you start from the beginning. (the needles were NOT moving on their own either due to vibration) overall one of the worst engines I've had.

I guess it's just a real crap shoot with that engine, I have the same Tower RTF. It took a friend of mine all of about 3 minutes to tune it to a nice idle & smooth transition & it's ran like a raped ape ever since. Not a deadstick one to it's name. He did this as another guy was telling us what a piece of crap engine it was & how we would never get it to run right. Lol he slinked away rather quietly after it was all dialed in, in just a few minutes.

Don’t give up on the tower hobbies Engine. I think a lot has to do with the way you tune the engine. If you tune it just right you will be happy you never threw away that engine. Trust me.

Go ahead and give up on it, but don't throw it! I had one for awhile and experienced the exact problem you stated. I called Hobby Services and told them I was unsatisfied. They told me to send it back for full credit. I used the credit and bought a ST G45 and haven't looked back. I understand the draw of the tower engine..BB,ABC and cheap, but you can get the same thing with an ST and it's a better engine.....I think they are offering a $10 gift certificate with the ST's now, so that will cover your troubles and shipping

Mike

Funny- I have one of these engines on my old pattern plane. The only problem it has is that I cant get it to stop running. (leaky bearings)......

Seriously, The engine can be tuned to be very reliable- Like others have said rich on the high side lean on the low. You will be tweaking it for the first gallon or so but once it is broken in it should be fine. (not a great engine) but good enough for a trainer.

does your glow plug have an idle bar? if not maybe try one

Hi... Thought I'd just add my input to this thread... I'm training a fellow member and
he has the tower 46...About two gal. through it now.. Anyway out of the box the engine
ran great. After break-in we have set still a bit rich.. And she ran great, a bit slow on
transition but good, she always hesitated a bit at lift-off, and transistion lagged slightly
in flight... But she worked well, after a gal. she started to dead stick slightly after lift
off.. We were slowly leaning it out through out the flights.. Anyway we checked all,
clunk, tk., line, removed cleaned needle valve/carb, new plugs, he was running towers
so I gave him a new OS#8 etc.. But still the same.. It would run great on the table,
pinch test, nose up, transition all showed setting were on.. But the same results...?? We
have other members that have had the same results and yet the have some/same
members that have more than one just run great??.... IMO...

This hobby needs the Tower type engines... So when you do have a problem engine
let them know about it and send it back for a fix/replace.... Don't just set it somewhere,
Let's not get them to stop produceing it, but repair/replace and make them better..

My trainee bought my used LA46... so he could continue his landing training... But he
is sending the tower back.....

Here is where you went wrong. You got it too lean. Forget what you
know about setting engines on the ground. This thing leans out a LOT
in the air. If you set it like you do for most other engines (a little rich from peak)
it will lean out and die in the air.

It has to be WAY rich on the ground. Its kind of hard to judge
but through trial and error and lots of deadstick practice you
can get it dialed in. Once you hit the magic combination it
actually runs really well.

Also it seems to be picky about plugs. The one we had did not
respond well to Tower plugs or os#8s. We had the best results
with a Fox idle bar plug. I dont really like Fox plugs but in this
case it worked a lot better.

Mike Hammer

That doesn't indicate a lean in-flight condition -- note it only dies when throttled back to idle.

Aside from low-speed mixture tuning, the idle speed may be set too low. Try cranking up the idle speed a bit (slightly greater throttle opening at idle).

the best suggestion I have for a Tower 46 is to firmly tape a quarter to the cylinder head and throw in the trash!!The quarter is there just in case someone finds it----at least they will have a quarter which will make it worth finding!

Mike, Totally agree with everything you put in the post about this engine. Just to add my $.02. I found the same trends when I used the Tower muffler on the OS and Magnum .46's and .50's. That muffler is amazing, It will add a little over ,1200 RPM's on 15% Nitro on other engines, over their stock mufflers. But the increase in performance also requires some refined tweaking to get the engine dialed in. The engine picks up allot more RPM's in the air, than on the ground, since the muffler sort of acts like a tune pipe, it will cause the engine to demand more fuel in the air than on the ground, therefor go lean and die, burn out the plug and maybe the engine.

Just for the sake of arguement, I put an OS .46 FX muffler on a Tower engine and found it easier to tune, but nearly lethargic in performance. I too, found that the engine likes an idle bar and a fairly rich setting on the high end and very lean on the bottom, similar to a large SuperTigre engine.

I have had several of these just for fun, to fool around with. I had one come apart before the first gallon, sent it to Hobby Services and got another new engine right back. It worked great, using your recipe. Like SuperTigres and Magnums, these engines need to be broken in and tweaked quite a bit for the first two gallons, but after that, they run like the proverbial scalded ape.

Remember you usually get what you pay for, but if it comes with a long warranty, make use of the warranty. I have had similar problems with Magnum .52's, but with a Tower muffler, good break-in and some patient tuning, they are awesome on power. If you are a Tower member, they usually double the warranty on all tower products, making some of their stuff a very good deal for heavy, prolonged usage.

Good luck and happy landings.

There is a fix for your sick tower hobbies .46 engines, I read all of the comments and symptoms of this poor "MISFIT" engine that we are all burdened with, Well my engine did relate to 100% of them, but not anymore. First of all the tower plug is not standard length and they will not work with this engine, Install a "FOX" idle bar plug, Not os #8 nor the # 3 for that matter. I'm sure they have their uses elsewhere. Change that darn rear needle carburetor to a front needle carb from a GMS .47 if you get dead sticks and you see bubbles in the fuel line, Also my engine has 2 head shims which make the compression a little high. I can get a very reliable low idle and only using a castor synthetic "5% nitro" fuel at 4300 feet of altitude, if you use higher than 10% nitro fuel in this engine then you will risk blowing glow plugs and probably detonation unless you use more head shims, My suggestion is as your engine gets older, use the higher nitro fuel so that it will run better because the tolerances weren't as good as when it was newer ( Here is a riddle of this relevance) The older I get, The better I was..... Let me know if this remedy works for your engine as it did mine, I know for proof of compliments from club members, I have a tower trainer with a tower .46 abc engine that climbs out like a homesick angel and it thinks it's half pylon racer.....and not one deadstick landing....Happy landings...

Thanks for all the info.Got with my instructor tonight and used a OS A3 plug and got the thing acting decent. Got it pretty lean on idle mix and RICH on high mix. Ofcourse I wont get to put it back in the air until tomorrow but it acted pretty good on the bench. It actually idled for 10 minutes or so. Transition from idle to full throttle was decent and it held up pointed up, down or on its back. Will get by the H/S and try a Fox plug and lower nitro. I'll run a gallon of that through it and see if we can't tweek and improve. That is one down and one to go. At least I have somthing to go on with the other since it was acting the same

Hey Mike,

I hear what your saying.... Before he finally bought my LA, we tried a new fox plug,
reset all to factory spec. rich rich and more rich... it ran.. I guess you could call it that,
but did not inspirer any confidence for practicing/learning landings...So we slowly
started leaning it 1/8 then test flew... Anyway we could never get it right... I think it
was just "one of those".... My main point was.... Don't stick that quarter on it and
trash it..... send it back for repair/replace.... This hobby needs good powered lower
cost engines... And tower seems to be pretty good at standing by them... And if "ALL"
send back the "Bad" ones.. They will keep??? standing by their warr. and hopefully
learn from the problem one's.....

If you take off the Tower "TUNED" muffler and put a regular muffler on the engine, most of your problems will go away. I liked the MACS "One Piece"

Enjoy,

Jim

That is actually a reasonable solution & the engine has sufficient power that the loss, resulting from the backpressure of the regular muffler, will not be crippling. The Tower muffler can be saved for something like a TT 46 Pro, or OS 46 AX -- both of which respond impressively to that tuned muffler.

You can also try stuffing some coarse steel wool in the Tower muffler (downstream of the pressure nipple) -- that works too.