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HelicopterEngines Plugs Mufflers Fuel › TT39 running rich about hover
09-08-2003 01:37 AM  14 years agoPost 1
airbailey

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Iowa

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i have a TT39 maveric muffler and it seems to run rich at about half stick but at full throttle it is fine and at idol it is fine. the head temp is about 200 deg at full throttle on a test stand i am running cool power 30% fuel

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09-08-2003 02:37 AM  14 years agoPost 2
Joe Ubaldo

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Grand Rapids, MI USA

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Trying leaning the low needle 1/16 of a turn at a time (but don't go too lean). The low needle impacts the carburation up to about 80% throttle opening.

What are you needles set at right now?
What muffler?
Standard or UNIFLOW fuel plumbing setup?
Header tank?

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09-08-2003 12:02 PM  14 years agoPost 3
airbailey

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Iowa

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high needle is 3 3/4 low is 3 1/2 i am running the maverick muffler

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09-08-2003 06:48 PM  14 years agoPost 4
RaptorPilot

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Newbury Park, CA

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Sounds like your low speed may be a bit rich, but it can be very sensitive so don't move it much. The TT39 can take 2 gallons to break in. Once it is broken in and you get the settings dialed correctly, it's a great engine. Here is a list of symptoms and what they mean:

Won't idle after a cold start ---- low speed is too rich
Crankcase is too hot for the "3-second touch" test --- low speed and/or high speed are too lean
Head speed decreases after liftoff, followed by a low frequency wobble --- high speed needle is too rich
Engine bogs on a full power climbout --- high speed needle is too lean

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09-08-2003 07:42 PM  14 years agoPost 5
Joe Ubaldo

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Grand Rapids, MI USA

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In2helis,

3 turns open on my low and high needle during break-in were way to lean. It's better to play it safe and start the needles at 4 turns each (mine needed 5 turns on the low needle to keep cool).

Now that my TT39 is broken in, I'm running 3.5 on the high and 4.0 on the low and it's running great at ? 225 degrees F measured with a Raytek.

The manufacturing tolerances vary greatly with theses engines so play it safe regarding the needle settings. The bottom line is there's not much risk in opening up the needles. There's a lot of risk turning them in too far.

Just my .02

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HelicopterEngines Plugs Mufflers Fuel › TT39 running rich about hover
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