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O.S. 160 Gemini problem

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O.S. 160 Gemini problem

Old 10-16-2010, 03:37 PM
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DMyer
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Default O.S. 160 Gemini problem

I recently got an old O.S. Gemini 160 twin for free... the one with an air bleed carb. I just started it and I could not get any power out of it. I am pretty sure I had both cylinders working - but it would only put out 5,900 RPM with an APC 17x8 prop. Transisition was awful. No amount of needle twisting made it any better. Is this one worn out, or could out of adjustment valves cause it to be this much off in power? Any ti[s would be appreciated as I am not a 4-cycle guy (yet).


dan
Old 10-16-2010, 05:26 PM
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Default RE: O.S. 160 Gemini problem

Answered my own question... nothing wrong with it... one of the glow batteries was low on power... with another battery I got both sides running - 8,100 RPM on a 17x8 and ran very smooth with a very nice idle.
Old 10-17-2010, 10:57 PM
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Default RE: O.S. 160 Gemini problem

I have the older and original FT-120 Gemini. Had a similar experience with the glow batteries. I now use two seperate batteries. Idles like a charm and sounds like an antique. I have it in a 1/4 scale cub. HoweverI could only get 7,500 rpm with a 16-8 prop.. noteven close to the advertised 9,000 rpm.
Old 10-17-2010, 11:09 PM
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Default RE: O.S. 160 Gemini problem

Hi Dan, glad you got that sorted.
Can you please tell mehow to tell if one cylinder is not firing ?

Thanks

Paul
Old 10-18-2010, 04:06 AM
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Default RE: O.S. 160 Gemini problem

Paul, the engine will hardly accelerate, run at low rpm and one cylinder will be much cooler to the touch than the other.

It will also sound like a single cylinder engine! - John.
Old 10-18-2010, 08:49 AM
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Default RE: O.S. 160 Gemini problem

When you get both sides running - you will know!!!! Night and day difference. I was not sure the first time myself but when both sides fired off I knew I had struck gold for this free engine.


I was real happy with the tuned 8,100 RPM with a 17x8 APC - on 15% 4-cycle fuel.... had a surprising amount of pull. I am going to try a Xoar or Vess 18x6 Beechwood Sport prop on it next as I beleive that will be a lot better than the current APC prop that came with the engine.

Dan
Old 10-18-2010, 07:35 PM
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Default RE: O.S. 160 Gemini problem

Thanks Dan :-)
Old 10-18-2010, 07:37 PM
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Default RE: O.S. 160 Gemini problem

Thanks John, that was very helpful, although I won't attempt to touch the cylinders to findthat out !! lol. :-)
Old 10-18-2010, 07:56 PM
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Default RE: O.S. 160 Gemini problem

Just feel the exhaust...
Old 10-18-2010, 07:58 PM
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Default RE: O.S. 160 Gemini problem

Thanks rafeeki, never thought of that....how silly !!

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