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TT 61 GP leaning out?

Old 12-30-2011, 05:23 PM
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skypiratescotty
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Default TT 61 GP leaning out?

well, i searched for a while with no answeres so i guess i'll pose the question here. I'm flying a TT 61 GP and it has gotten to the point where it leans out no matter how I set the HSN. It has maybe 1 /2 gallons through it and is a powerhouse even running 1/2 turn on the rich side. anyway, second flight of the day it seemed to be leaning out when climbing for a loop so i landed and let it cool down a bit. refueled ( 10% coolpower, brand new jug ) and fired up. advanced to full throttle and pointed it up and it sagged. this is where i get lost. i ran the HSN closed and then opened 3 turns. still leaning out, kept going in 1/4 turn increments until i got 5 1/2 turns out and still leaning so i packed it up. i just pulled it off the plane and checked head, backplate and carb mount bolts. everythings tight and no leaks except the prop shaft will move in/out like 1/16" that i never really noticed before. bad front bearing? there is no side to side play and when it was running the last time it looked smooth except for revving/ sagging flat and level at WOT. i don't know.....any ideas would be greatly appreciated!!

Scotty
Old 12-30-2011, 06:19 PM
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delman
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Default RE: TT 61 GP leaning out?

Check that you carb is fully seated on the case after loosening the screws and retighten. Also check your fuel lines in and outside the fuel tank for pin holes. Those items can cause it to lean out. A clogged nipple on the muffler (pressure fitting) can be at fault too.
Old 12-30-2011, 06:42 PM
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Default RE: TT 61 GP leaning out?

will do....thank you!!

Scotty
Old 12-31-2011, 01:42 AM
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Default RE: TT 61 GP leaning out?



I have a few ASP engines with a problem similar to that. Ifound that there was air leaking aroung the o ring on the HS needle. I cut a thin washer of small diameter fuel tube and slipped it over the thread so it was seated hard against the thread and the outside wall. This will stop any air getting in. Also I have done the same on the LS needle as well just for safety.
Hope this helps
Old 12-31-2011, 03:37 AM
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skypiratescotty
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Default RE: TT 61 GP leaning out?

thanks cymaz

ya know, i inspected that o-ring and it did look like it doesn't quite fill the groove that it is seated in. i'm gonna replace the o-ring that is on the carb barrel to engine today so i might as well do the one on HSN as well. i appreciate the help.
Old 12-31-2011, 03:47 AM
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Default RE: TT 61 GP leaning out?

The TT GP 61 doesn't have a front bearing. It ran well for one flight? Check fuel lines and clunk in tank.
Old 12-31-2011, 08:28 AM
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Default RE: TT 61 GP leaning out?

thanks turbo
it sure looks like a bearing to me. i put many a bearing in my skateboard wheels back in the day and this looks very similar but of coarse i could be mistaken. i just replaced o-rings on HSN and carb to crankcase joint and also bolted a different engine on the plane. gonna run the OS 65LA that I know is perfect and go from there. also got new fuel tubing this morning so hopeful to have it worked out soon.

thanks again
scotty
Old 12-31-2011, 08:43 AM
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Mr Cox
 
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Default RE: TT 61 GP leaning out?

I don't think that there is any .61 GP engine. It sounds like you have the .61 Pro (ballbearing, twin needle carb) rather than the .65 GP (plain bearing, airbleed carb).

The Pro version has a twin needle carb, you may then have leaned the low-end needle too much so that it is now also limiting the full throttle setting. Unscrew the low-end needle a little and see if that helps on the high end too.
Old 12-31-2011, 12:54 PM
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Default RE: TT 61 GP leaning out?

Hi!
Yeah!
No Ball bearing in the TT GP engine! But! How is your tank placed? That's the main problem I think!
It's very important that the tank is placed so that a line drawn trough the center of the tank is running through the carb fuel intake orifice when the plane sits horizontal!
That's the "Tank mounting rule" ...and it must be obbeyed if you want your engine running without problems.
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Old 12-31-2011, 03:00 PM
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Texastbird
 
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Default RE: TT 61 GP leaning out?

Well, if you are running Cruel Power in a bushing engine, that might be part of the problem. They really need some castor oil to seal the bushing main, and not run hot.
Old 12-31-2011, 03:06 PM
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Default RE: TT 61 GP leaning out?

Scotty
Your TT GP 61 has an air bleed carb.Make sure when you adjust the low speed mixture ,
clockwise for rich,and counter clockwise for lean.
Old 12-31-2011, 04:12 PM
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Default RE: TT 61 GP leaning out?

thanks for all the tips fellas!!

it is definately a TT 61 GP as it has GP on the engine left side and 61 on the right. tank is situated such that the centerline is even with carb, maybe 1/8" inch high but certainly no more. replaced both o-rings, removed tank and inspected ( no sign of pin holes ) and replaced fuel lines anyway. i did notice the air bleed seemed to have backed out maybe from vibration but idle has been great and so has transition to WOT. The problem is only at WOT. At idle i could point the plane straight up and no change but i think I'm still going to put LSN 1/2 way across the opening and re-tune from there. by the way, there are no air bubbles in the fuel line at any time. it got late and i didn't get to run it but will first thing in the morning and see what happens.

thanks again for all the input!!!!
scotty
Old 12-31-2011, 04:22 PM
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Default RE: TT 61 GP leaning out?

here is a pic of the set-up. not really any different than most of my other planes. i almost alway side-sling em' and get the tank as close as possible.
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Old 12-31-2011, 05:53 PM
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Mr Cox
 
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Default RE: TT 61 GP leaning out?

Okay, that's the GP version. The airbleed will not affect the high end at all. It might just be an obstruction in the fuel at the position of the seat for the needle.
Old 12-31-2011, 07:27 PM
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Default RE: TT 61 GP leaning out?

cool, thanks Mr Cox. that's an easy fix i've done with an older Enya 45CX that sat for years. I use a flavor injector and connect fuel tubing so i can suck a couple of ounces fuel from jug then connect to fuel nipple on needle valve and pressure blast the sucker open. works like a charm or use air hose and blast it out.

thanks again!!!
scotty
Old 01-01-2012, 12:05 PM
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Default RE: TT 61 GP leaning out?

Hi!
When an engine gets a little worn (Piston to cylinder fit not as tight ) then the carbs fuel sucktion ability becomes not as good as compared to when the engine was new. Then it's important that you do whatever you can to help the engine suck fuel! That's your problem!

To have an engine function properly includes using 10-15% nitro fuel, A 12x6 ,13x4,13x5 or 14x4W Prop( Best props are APC and RAM). Medium hot glow plug like a OS 8 or Enya 3 glow plug (No idle bar plugs please). 12 oz tank (not bigger)! and probably in your case ...get rid of that small silencer that robs power and use the standard TT silencer which probably have less exhaust diameter outlet compared with the after market silencer you have on now. A silencer with less exhaust area gives much better fuel draw!

Old 01-01-2012, 12:28 PM
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Default RE: TT 61 GP leaning out?

Great!!! Thanks for all the suggestions fellas!!!! My TT 61 GP is ripping holes in the sky once again. I swapped out an OS 65 LA and did a flight to make sure it wasn't a plumbing issue it plane flew great. Put the TT back on and same problem so I removed needle assembly and disassembled the needle valve completely and blew though the fuel inlet nipple. There was some initial resistance and then a "POP". Put it all back together and the thing runs perfect. Turns out there was a small obstuction in the nipple causing the problem. Just goes to show that fuel filters in the fuel jug and the airplane are a must!!!!

thanks again!
Scotty
Old 01-01-2012, 05:51 PM
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Default RE: TT 61 GP leaning out?

Sometimes, you get lucky by pumping fuel thru the rnv in reverse direction.
Old 01-01-2012, 08:45 PM
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Default RE: TT 61 GP leaning out?

I've seen fine whiteish fibers accumulate around the NV tip. My guess is its some sort of organic junk wafting about from the lawn being mowed that's so small it passes through a normal screen type fuel filter. It takes a while for that stuff to accumulate to a level where its impeeding fuel flow.
Old 01-01-2012, 09:03 PM
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Default RE: TT 61 GP leaning out?

I use sintered bronze fuel pickups and a third line for fueling.


Ed Cregger

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