Hi,

Somewhat new to the gas planes. I have been flying gliders for years and have went and bought a trainer plane. It has a Tower Hobbies .46 engine on it. I have done the break in on it and it seemed fine. When I went to the field to fly it though it seemed to have problems. My situation is the idle is running great but when I move my throttle to half way the engine is running at full power. When I move the throttle all the way up, it goes back to idle. Any advice would be much appreciated. Thanks in advance.

Need more info. You have checked the throttle body to ensure you don't have some kind of funky mix running in the radio, right? Throttle should be fully open at full throttle, etc etc.
At full throttle, does idle sound different than at idle setting? A little faster but very rough? You did break-in and have manual, and have read it carefully, right? All that stuff about how to set the high speed needle? Sorry to seem patronizing. Gotta ask. Does engine continue to run at full throttle or does it die after a few seconds? Sounds like it's running rich to me. Turn the high speed needle at full throttle and see if engine picks up speed when you sloooowwllly turn the needle in.

You could also do a search here on RCU, there was a post not too long ago which had some excellent setup advice in it.


Andy

Thanks for the help a651. Yes I did check the mix. Idle does sound different at full throttle. It does sound rough and it sounds as if it wants to stall. Engine does continue to run at full throttle but only when I have the throttle control on the radio at half way up. I did try turning the needle and the engine did pick up some speed. Still sounds like it wants to stall. Thanks again for the advice.

This is what I would do, with the little info given.

Turn the high speed needle valve out to richen it up. From what it sounds like about half a turn may work.

Then set then engine up for a good idle, run the engine to full power. If if bogs at all, lean the low end needle out a little (1/8 - 1/4 turn.) do this until you get the low needle to advance the engine up to full power quickly and ther is no aparent engine bogging or dying.

Then run the engine to full throttle, and set the high speed needle valve. Remember that with a new engine, or one with a remote needle to give then engine a few seconds of run time per click of adjustment to allow it time to take effect! What you want is to SLOWLY bring the engine to peak lean. This is the point that any more leaning of the fuel will result in a LOSS of RPM. Once you have found this point, RICHEN the needle high speed needle to about 400 - 500 RICH of PEAK Lean. Let then engine set for a few seconds, then thottle down to idle.

If the engine is idling at the same rpm, or slightly away from it, you are close! If the rpm is different, reset your trim setting on your transmitter to reset the idle to a good idle rpm (around 2200 - 2600 is fine.)

Now take the throttle and rapidly apply full power. If the engine bogs, lean the low end out again. If it dies, richen the low speed needle again.

Once this is done check to see if the High end rpm is around where you set it earlier. If the engine is holding somewhere around 400 - 600 rpm RICH of peak, and the engine accelerates from idle to full power with little to no hesitation, YOU'VE GOT IT!!!

The reason for the repeat of the process after doing it the first time is to ensure that everything is set right. On most RC engines the High speed and Low speed needle will vary one another. If one is set way out of whack, the other will have to be set out of whack. This will go on and on, till you get a bad running engine! At this point it is best to start from the beginning and make sure everything is set right. Starting with the factory recommended needle settings is a GREAT place to start!!

Te reason I recommend to start this process by richening the high speed needle is to make sure you aren't running too lean! This takes one of the factors out of the picture. Then you get the low end close to running right. Then you reset the high end needle to where it needs to be. Then you check / reset the low end needle to the newly found good high needle setting. If the high rpm is way off after resetting the low end to the new high end, reset BOTH needle valves to factory settings and repeat process.

Just my thoughts,

Reg

[link=http://www.rcuniverse.com/forum/Engine_Problem/m_1764767/tm.htm]Click here[/link] and read the 3rd post in the thread. It may help you. It sounds like your High speed needs to be leaned out.

With the plane on the ground open it up wide open. then pinch the fuel line. if the engine picks up a lot of rpm before it dies you are too rich.