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Engine Gurus, I need help

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Old 01-02-2003, 02:23 AM
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Tired Old Man
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Default Engine Gurus, I need help

I need some help from all of the 2 stroke engine gurus out there. And I hope there are a lot of you.

Here's the set up.. Lanier Ultimate Pitts, OS BGX-1, 35cc glow engine. Old style engine with front needle carb. Engine has a little over 2 gallons of 10% nitro fuel through it. 18% or better oil content. I have replaced all the o-rings on the carb, high, and low needles with factory new. Excellent engine compression.

Side mounted engine using the radial mount provided with the engine. OS #8 glow plug. Bisson Pitts muffler with pressure tap.
Zinger 18/6 balanced wood prop. Have also used 18/8.

24 oz. Dubro fuel tank, set up at even level with carb inlet nipple. Three line fuel line system on tank. One line from muffler to tank, one line for fill and de-fuel through fuel dot, one line to carb. Both fill and engine lines are clunked. Line to engine is large tubing. No leaks found anywhere. No fuel foaming noted.

Field elevations used are from sea level to 800 feet above sea level. Problem occurs at any weather and temperature condition.

The engine will start and run for awhile. Regardless of the high and low needle settings, it will lean out and quit in flight. Set the needles another way and it will richen up in flight and quit It has even leaned itself down to sputter in flight, then went to reverse rotation after I played the throttle attempting to keep it going.
It acts like it has a fuel draw problem but I cannot figure out why.

I've tried everything I can think of, and I'm hoping someone out here has more ideas. I have gotten really good at dead stick landing a 14 lb. bipe If you do, please share them with me.

Silversurfer
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Old 01-02-2003, 03:18 AM
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Default Engine Gurus, I need help

When it gets hot things will expand and it is drawing in air. Check the orings on the carb. Just something you can check.
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Old 01-02-2003, 03:50 AM
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Default Engine Gurus, I need help

SOUNDS as if the engine isn't getting enough cooling,have you tried flying without the cowl,had the same problem with a edge,had to open a very large area for the hot air to exit the cowl.
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Old 01-02-2003, 12:50 PM
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Default .

maybe 'o' ring on the needle valve, air in fuel line, damaged needle valve?
could try flying without cowl and placing a piece of large fuel line over the needle valve. i have had needle valve turn due to vibration and the 'clicker' not holding needle valve in place also. could be many things up to and including bad fuel....
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