ABC is a fine engine, I have abc and ring types. ABC are naturally tight at top of stroke. Your motor needs breaking in, that is all and do make sure all washers are there. I am not familiar with TT engines so I can not tell you about specific washer placements. I always use electric starter and spinner as I feel it is safer (and I am lazy- let's admit it OK) Worse come to worse and they are right about ABC (and they aren't) you already have it, what ya gonna do? Throw it away? Fly the dang thing after you run another 3 tanks thru it at home breaking it in. Ya got the time don't you? If your motor is tight thru entire rotation, something IS wrong/missing. Keep at it, it will come. Wanna spend some money? Don't buy engine- get electric starter and battery for it. IMHO

No double nut on 2 stroke, common on 4 stroke though

sa what am I to do?? I do have a problem of this engine don't want to run at any thing below half throtle (acts like it wants to run but cant, I think we allready know why.) and I need idle to taxi. so should I just get me a extra engine mount from teh hobby shop and fashion me up a engine test stand?? that would be easier than trying to hold down a light easily breakable plane for the hours its gona take to make this engine into a broken in engine. mater of fact I think that will be todays project. take some wood and make an engine stand that I can clamp down to some thing and let run through a couple tanks of fuel.

Take an old belt or piece of rope and loop it around the tail. Drive a stake or tire iron in the ground for an anchor to hold the plane in place. Shouldn't hurt anything. You said ground was soft from rain, should be easy enough to get stake in ground. Will motor not idle down because too tight or because mixture is wrong? Has it EVER idled? Like before the prop came off did it have these problems? Try to go back to the last KNOWN good condition. Had an Evolution motor the other day with a missing washer behind prop drive washer, felt OK until prop tightened down. Then could not turn it. Somewhere along the way a washer had come up missing. This MIGHT be your problem. Anyone out there more familiar with Thunder Tiger engines please chime in here. Sarges- is there a manual for your motor? If so does it show a part list or diagram? Look for a washer that may be missing. Don't give up. Hope you didn't run engine too lean and do damage to cylinder walls. That is anther slim possibility. Wish I could be there to look at it first hand.[&o]

Bruc

Does the TT have ball bearings or bushings. On the EVO it has bearings and on the one I was talking about it was missing a thin washer that rode on the front of the front bearing behind the prop drive washer/flywheel. Without it the drive washer was dragging on the nose of the engine casting and sounded just like the complaint you are making. We found a small diameter thin washer to place in there and all was OK. You might try looking for such a washer around the house. When you had the prop come off the other day, did the drive washer behind it on the shaft also come off? If so, that is probably what is going on. These are VERY close tolerance machines you're dealing with.

Bruce

I looked at the exploded diagram found in the manual and all washers and prop nuts are accounted for (I got a replacement prop nut and prop washer from the flying field, they have a box of extra little parts that people find lying around on the ground).
thing is when I run it at (aproximates here) 1/2 or more throttle it runs and does good, no sign of death. if I throttle it down it will die and the prop will be stuck at the "hard spot" im now assuming is TDC (Top Dead Center piston position). now I wonder if I let it run long enough to get hot ,like leave it on full throttle for 10 min., and then throttle it down to see how far I can get before I kill it. if its just tight when cold it should idle fine when warmed up and should run with a normal attitude. am I right??? Might be the basis for an experiment.

Is rotation stiff thru entire rotation or just neat TDC?

It really sounds like the low end is not set right. I'm assuming it's an "air bleed" type carb, which means the low end needle adjusts the amount of air the carb gets (rather than fuel). If this is the case then turning the low end needle clockwise will richen the mixture, counter-clockwise will lean it.

First thing I'd do is try adjusting that low end. If that doesn't work, then I'd say something truly is wrong with the engine.

Sure wish I could actually get my fingers on that thing for a few minutes.
Dennis-

just tight at the TDC spot. is realy easy to turn up to TDC point.
DBCherry: which way would you recomend to turn the air bleed screw?? richer? leaner? need more info? I had a pic around here some where.

It is a characteristic of ABC to be tight at TDC, it would be bad if not. Again, not familiar with TT carbs so I will stay out of that issue except to say mixture may well be the problem. You never said if it ever did idle properly before. If so, what happened to motor just before it changed to where it would not? ABC engines ARE in general fine engines. You might have a bad one but I doubt it and it should idle fine and have a good midrange and top end as well. Sorry, but I feel the guys at the field may have steered you wrong on this issue. I know it is hard to know who to trust at times. I have several of both ABC and ringed engines with no real preference for either type. Yer having a little bad luck, let's not blame a whole class of engine, OK?

I'm not sure if there is a problem here. The fact that you can get the engine started leads me to believe it's not excessively tight. I would have to agree with DBCherry, sounds like it just isn't tuned correctly.

sarge,

I will assume this is a new TT .42 GP or at least a air bleed carb. If it is not, forget the following: First Be sure to break the engine in with 3 or 4 tanks. I wont go into that as there is many ways to do that. Search the forums for some great expert advise. Then, adjust the high end needle 3 or 4 clicks of the highest RPM. Next go to the idle tuning.

Without knowing what the engine sounds like when it goes to idle, I'd have to guess. I'd check the air bleed hole in the front and see if the idle screw is blocking 1/2 of the hole. That will be a good starting point. Assuming you have set the high end to full RPMS and backed off 3 or 4 clicks, and you still cant get it to idle start turning the idle air bleed screw out to lean about 1/8 at at time. That will be leaning the mixture. If it is getting better, you will be going in the right direction. If not set back to 1/2 and start turning it in 1/8 turn at a time. Then when you get it close, you'll have to go back to the high end and retune that. Then back to the low end for fine adjustment. You should be good to go.

ABC engines are great. They are no worse than a ring engine. Sounds like the guys at the field are from the old ring school. Or jellous of you purchase. Soon you will be flying rings around them and grining.

Once the high speed is adjusted, slow the engine down to the point where it begins to falter. holding it there, pinch the fuel line with fingers or needle nose pliers (be careful of prop at all times)(this will LEAN the mixture) if the engine accelerates a little before quitting then you are too rich. If it quits immediately, you are too lean. Adjust bleed screw accordingly and try again lowering speed every time until you get idle speed. It is a balancing act but it can be done.

If your engine only wants to work at wide open throttle then the fault may lie within the LOW SPEED adjust tneedle being too lean. The low speed needel adjusts from idle to upper mid range; the high speed needle works adjusuts only the wide open throttle portion.
Please have an experienced modeler fiddle with the low speed needle as they are a bit tricky

Im not shure why U took the time to bold all of that. but if you took the time to actualy read what has been written you would see that is a carb equipt with ONE neadle valve and one Air Bleed Screw. there is no low end needle, period. thanks for trying but u need to look before you leap.

Ok, end rant.

bruce: ill give it a try when I get me a engine stand set up. not gona try to hold down plane while at full throttle, nuh-uh![&o]

Did you get my PM ?

ya i got it. prety shure it just needs a little adjustment. like I said once I get that stand made I will get to tuning it and Ill post here if I need any further help.
thanks for your help bruce, your a god send for us newbies.

OK, keep me in mind.

Sarges,

Go easy, we know your frustrated.

I was just looking at the specs on that engine. In the GP series they only show a .42 so assuming that is the engine we are talking about.

If you already do not know, on almost all glow engines, the Air Bleed/Low Speed needle is controlling the mixture from idle to mid-throttle, from that point the high speed needle takes over. I agree, being that you cannot run anything below half throttle you are lean. If it was sloppy rich it would run but either die from being flooded after a few seconds and most likely spitting fuel when you throttle up from idle, but being lean would kill the engine pretty quickly once the Air Bleed screw takes effect coming down from full throttle or going to half throttle or better from idle without spitting fuel.

I found this from a thread a year or so back on setting the Air Bleed Screw. Although he mentions the OS engines the thread was on the TT42GP

He goes on to say that this worked well for him. When tuning remember that an air bleed carb is opposite from a low speed needle valve carb. Also, make super small adjustments, I am talking about 1/16 to 1/8 turns at a time, then run it. As was mentioned before, you must have the high speed needle set properly first.

On an Air Bleed, turning the screw out leans the engine while turning it in richens it. You are actually adjusting air, not fuel. This was mentioned before but I thought I would reiterate it. After reading tons of posts on this engine, it being tight at TDC seems to be pretty normal and once it is broken in it will last for ever and the tightness will not be as bad.

If you have already tried this or I am being to redundant, just ignore this post

thanks buba gates.
I went out to mess wit it today (it was on the plane) and got it to idle with out going any where. I got it to throttle down to where if you looked down in the carb there is just a tiny little hole any littler and it will promptly die from the sputters. thanks for teh help. now all I gota do is adjust those z-bends so that the control surfaces dont need so much trim (dang aleron needs full right trim tab plus I got to hold the stick over a little to keep them level) then I can confidently go to the flying field and know all my bases are covered. That way I can concentrait on flying the model (and not crashing it).
I would be still tuning it but the hot shot 2's battery got to weak to start the last time. so its been on teh charger for atleast a hour.

People spend thousands of dollars on their planes
buy all the gear like starters and electric fuel pumps
buy all the spares that you can afford

and go to the Dollar Bargin Bins to buy tools

you will not strip a nut with the correct tool ( ring spanners)

an adjustable spanner has no place in a modelers toolkit

Very cool Sarges

You mentioned about adjusting the z-bends. I hope you really me the clevises. These are the little plastic/metal peices at the end of the rod usually out at the surface. The way I do this is to turn the radio and airplane on and have the trims where then need to be and measure how much the surface is deflected. The I center the trim and turn the clevis until it gets the same deflection. Work slowly and methodically on all of the surfaces and you will be able to get the trims centered well and can concentrate on flying.

A good rule of thumb is if you need to rasie the surface you turn the clevis towards the surface and to lower the surface you turn the clevis away from the surface

Uhhh, ok. thanks[8D]

well the LT-40 ARF did not come with enough "snap close" fitings for all control surfaces. The instructions called for Z-bends on the alerons so I tried to make Z-bends with a needel nose pliers and a pair of flater nosed pliers. well the bends did not come out well. they cinda did not come out at the right spot so the alerons are kinda screwed up. the only other flight control surface im worried about is the elevator. it can be adjusted, thats not what im woried about. im worried that my elevator is warping on me. It sorta looked like it was warping. that and I need to peel away the covering and do some seriose glueing on the ruder. it wobbles side to side. I did not notice any thing when I was buying it but it definitly has it now. so i gues I need to order some glue and push rods conectors.

nener nener I got a reason to go to tower!!

Good to see motor is running now.
As for ailerons, forgive me if I repeat what you already know, OK?

1. Turn on radios and center ail trim control
2. Make sure ail servo horn is centered (perpendicular to case) if not remove center screw, lift off horn/arm and adjust to center (may need to rotate to new position completely). reinstall horn and screw
3. turn off radio for now. If at any time you think you may have moved servo, turn radio back on and allow it to recenter itself.
4. Measure and mfg pushrods to fit between servo and aileron torque rods. Put clevis at torque rod end.

MinnFlyer- I bet you have a nifty picture you can post for him of this.

5. Make sure both ailerons are in same relative position to wing (up/down), may be able to reference to a wingtip or something else static.

Attached are links of hardware you could use, there are other types also but these would work good on a trainer. Wire would only require one simple cut and a 90 degree bend, not a z-bend. Your choice, I'm sure more options will be offered.

http://www2.towerhobbies.com/cgi-bin...?&I=LXAZC3&P=0

http://www2.towerhobbies.com/cgi-bin...78&FVPROFIL=++

Good luck
Bruce[

ABC engine sucked competely!! no offense but i had one of tower hobbies abc .46 engine, and i bolted it on tower hobbies fun 51. At first, it run just fine but more and more i pushed the aircraft to the limit such as hard snap rolls and aerobatics moves with heavy G pulls. the engine seem to hate me more every time I put it in the air. Just before i crashed on take off, the engine had to be on wide open trottle for whole time so it won't quit but every time, i land the engine quits and deadstick everytime. so i decide to dump the engine and replace with .50 ringed SX O.S. engine. I love that engine.