Transition Problem
10-29-2003 | 03:39 PM
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From: Charlotte,
NC
Transition Problem
Help!
My son has 2 motors with the same identical problem, a Tower Hobby 75 (15 flights) and an OS 46 (60 flights). About 6 weeks ago the TH 75 started hesitating at throttle up, it recovers and flys fantastic until you have to do a quick throttle up again. He has learned how to DEAD STIK rather well lately. We've changed glow plugs several times. Now his OS 46 has started doing the same thing, exactly the same thing. Several of the guys at our small club have tried to help me tune the motors but with little success. The OS has 51 flights on it and has been "tweaked" only 3 times in the last year prior to this problem starting. I have changed fuel since it appeared to be the only common thread but still have the same results.
Any help would be appreciated.
David
My son has 2 motors with the same identical problem, a Tower Hobby 75 (15 flights) and an OS 46 (60 flights). About 6 weeks ago the TH 75 started hesitating at throttle up, it recovers and flys fantastic until you have to do a quick throttle up again. He has learned how to DEAD STIK rather well lately. We've changed glow plugs several times. Now his OS 46 has started doing the same thing, exactly the same thing. Several of the guys at our small club have tried to help me tune the motors but with little success. The OS has 51 flights on it and has been "tweaked" only 3 times in the last year prior to this problem starting. I have changed fuel since it appeared to be the only common thread but still have the same results.
Any help would be appreciated.
David
10-29-2003 | 04:09 PM
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From: Dix Hills,
NY
RE: Transition Problem
Tom Kat:
This could be any one of many problems. However, since the engines have been run in and apparantly tweaked properly, I would venture a guess that it's probably a fuel issue.
There could be a leak at the fuel tank seal. Tighten the screw that holds the rubber stopper a little bit - not too much. Change the fuel tubing and the clunk. Tubing loses its elasticity after a while. Debris can clog the clunk, etc. Make sure the muffler's pressure port is open and not clogged. Change the tubing going from the muffler to the tank. Watch the fuel going through the tubing for air bubbles.
If none of these fixes remedies the situation, then the engine will need to be examined more closely.
Good luck.
Pat
This could be any one of many problems. However, since the engines have been run in and apparantly tweaked properly, I would venture a guess that it's probably a fuel issue.
There could be a leak at the fuel tank seal. Tighten the screw that holds the rubber stopper a little bit - not too much. Change the fuel tubing and the clunk. Tubing loses its elasticity after a while. Debris can clog the clunk, etc. Make sure the muffler's pressure port is open and not clogged. Change the tubing going from the muffler to the tank. Watch the fuel going through the tubing for air bubbles.
If none of these fixes remedies the situation, then the engine will need to be examined more closely.
Good luck.
Pat
10-29-2003 | 04:41 PM
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From: Charlotte,
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RE: Transition Problem
Bob_nj,
The OS 46 is turning a Master Airscrew 11/6 with a K&B 1L plug
and the TH 75 is turning a 12/8 with an OS idle bar plug. Sorry I don't recall the number but I'm at work (notice I never said working) and the planes are at home.
I will check fuel caps and clunkers tonight as well. I'm very new to tuning motors so I'm assuming that if the low end needs adjusting it probably is too lean. Am I guessing in the right direction?
Thanks for the ideas. I'll let you know what comes of this,
David
The OS 46 is turning a Master Airscrew 11/6 with a K&B 1L plug
and the TH 75 is turning a 12/8 with an OS idle bar plug. Sorry I don't recall the number but I'm at work (notice I never said working) and the planes are at home.
I will check fuel caps and clunkers tonight as well. I'm very new to tuning motors so I'm assuming that if the low end needs adjusting it probably is too lean. Am I guessing in the right direction?
Thanks for the ideas. I'll let you know what comes of this,
David
