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Saito 125 problem

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Saito 125 problem

Old 02-01-2007, 11:24 PM
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oregonrc
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Default Saito 125 problem

I've got a new H9 Showtime with a new Saito 125 on it. I broke it in fairly rich for about 50 minutes before I maidened the plane. We tached the engine at 9300 RPM before backing it down 300-400 RPM before flying it. The first flight the plane seemed to lean out and died. We restarted the engine, richened it up and the motor seemed to cavitate. I brought the plane in, richened it a little more and it seemed to have no power at all and would barely respond to throttle inputs. Here's the question. On the ground, the engine runs flawlessly. Is it possible that the cowl needs to be cut further? At present, the cowl has the stock intake holes, clearance holes for the valve covers and for the exhaust to exit. The general concensus at my club is there aren't enough outlet holes in the cowl and the air is compressing under the cowl. It makes perfect sense to me. Anybody have the same kind of experience? Thanks!

Dave
Old 02-01-2007, 11:59 PM
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rc-sport
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Default RE: Saito 125 problem

How big is the hole in the bottom? If it was over heating it over heat on the ground too. Have you checked your fuel lines for leaks.
Old 02-02-2007, 02:17 AM
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Penuts
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Default RE: Saito 125 problem

I would suspect a air leak somewhere,Check your pressure line from your exhaust to your tank also, A air leak will lean out your engine and quit in the air but run fine on the ground.
you should be able to tell if its running hot when you landed.as far as air flow goes if you need more air to exit the cowl, increase the exit port, just open it up some.
Might be a good idea just to replace all your fuel lines including your pressure line from your exhaust to your tank also. You got a great engine there, my runs fantastic and i love it.
Good Luck
Old 02-02-2007, 03:24 AM
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oregonrc
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Default RE: Saito 125 problem

I don't understand why an air leak would cause the engine to run differently on the ground then it would in the air. A loss of pressure should have the same result on the engine whether it be on the ground or in the air, shoudn't it?
Old 02-02-2007, 03:40 AM
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Default RE: Saito 125 problem

I had a Saito 72 break a con. rod, because of overheating. The front of the cowl was all open, and there was a large opening underneath. The engine was mounted upright, and ended up being in a dead air corner. I learned the hard way to make sure the exits are 2 to 3 times as big as the intakes, and make sure the airflow passes over the engine, not by-passing it.
Old 02-02-2007, 03:12 PM
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Default RE: Saito 125 problem

Engines can run lean in the air even though they run fine on the ground, not sure why but they do. Check your lines before you cut up your cowl or you could remove the cowl completely and fly it that way to see if it over heats. My money is on the lines having a leak.

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