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Poulan 25cc Featherlite needs help

Old 03-28-2010, 10:18 AM
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Default Poulan 25cc Featherlite needs help


Ive got a Poulan trimmer engine I converted. It runs OK, easy starts , good idle. The problem is it acts cold at full rpm. It runs rich for about 10 seconds at WOT , then its like it heats up and it smooths out, and the rpm goes up to a proper 2 cycle operation. I tried leaning the high end , but it leans out once it heats up at WOT. Would a hotter range plug help? If it goes back down and idles for awhile , it seems the engine cools back down, and it does the same thing all over again. Thanks, flyrc
Old 03-28-2010, 10:59 AM
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Default RE: Poulan 25cc Featherlite needs help

Instead of cooling down, I am thinking it is loading up with fuel due to a rich idle. The fuel can drop out of suspension at idle if the mixture is rich, and accumulate in the crankcase. Then when you go to full throttle, the rush of airflow in the engine scoops up the fuel and the mixture goes rich until it burns out the excess.

My flying buddy had this problem, but never noticed it because he never let the engine idle for very long. However he did most of his flying at around half throttle and his mixture was rich. He complained about the engine running differently when he first started inverted flight. When he went to show me the problem, I noticed that as soon as he turned the airplane inverted, a puff of smoke came out and the engine sounded rich. Getting the idle/midrange mixture leaned out and optimized fixed it. (Note that his installation had the cylinder in the upright position.)


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