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OS.61 hard to start

Old 03-01-2011, 10:02 AM
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Kaos
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Default OS.61 hard to start

I have an X-Cell Custom (model 1003, I think) with an OS.61 SF engine. It only had a gallon of fuel run through it many years ago and then was stored in a clean, dry environment. The whole machine is in pristine condition and was very carefully built, including some nice upgrades.

My problem is getting the engine to spin. After installing my radio system and getting it carefully programmed, I ran the engine. This was several weeks ago and it was a fairly warm day. I had some trouble when my Sullivan starter refused to turn the engine over when using my flight-box built-in 12v @ 7Ah battery. I got out my nearly-new, freshly charged RV battery and the engine spun right up. It has a beautiful, smooth idle and excellent throttle response. I let it idle for several minutes at a time and it did not load up or stumble. I did not fly it, however.

I had to delay my first-flight for weeks due to windy weather or rain. Finally, a beautiful morning arrived and I loaded up my X-Cell and equipment and headed out to our local flying field. My Sullivan starter refused to turn the OS.61 over, even though I had just installed and charged a brand new 12v @ 7Ah battery in my flight box. So, I borrowed a starter and larger battery and still no go. It was a cold day, perhaps about 50 degrees.

So, I ordered a Hobbico Torqmaster 180 starter and it arrived yesterday. Would you believe it, still no go! Even with my big RV battery! In all attempts to start at the field, or just spin it in the shop, I did remove the glow plug in an attempt to blow out any excessive oil, or whatever. The engine spins up great with no glow plug. After doing that exercise last evening, I reinstalled the glow plug and finally got the Torqmaster to very slowly flip the engine over. It was about one revolution every 2 seconds at first, then it finally starting spinning fast enough to start.

The engine seems to have very high compression, and now I'm beginning to think it might be an ABC engine, which I understand have a choked cylinder, meaning the piston fit near the top of the compression stroke is tight, particularly when the engine is cold. With the glow plug removed the engine turns over by hand quite easily, although I can feel just a bit of
resistance near TDC. And as I mentioned earlier, the engine runs and idles like a champ once started, and it feels very smooth.

With only one gallon of fuel through it, and assuming that maybe it's an ABC engine, can I conclude that it is not yet fully broken in? Or, do I need to warm the engine is some way before running it?

TIA,

Kaos
Old 03-02-2011, 01:29 AM
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tadawson
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Default RE: OS.61 hard to start

Myself, I would look at the wire size from your battery to the starter - too small, and it won't give enough current for *any* starter to work . . .

- Tim
Old 03-02-2011, 07:49 AM
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Kaos
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Default RE: OS.61 hard to start

Good point, and that did occur to me. Funny thing is, both of my starters have the original wires and they look to be of a pretty heavy gauge. And I don't use extensions. I might try replacing the wires anyway with a heavier gauge. I don't know what else to try.

Does anyone out there have any experience with this particular helicopter engine (OS.61 SF)?

-Kaos
Old 03-02-2011, 08:47 AM
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BarracudaHockey
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Default RE: OS.61 hard to start

You can try holding it on its side a bit towards the muffler, also make sure the fuel line is clamped until right before you start it.

ABC engines are tight. My Sullivan is powered by 2 3S lipos because I had an Avant 90 that was a pain to start and that was a ringged engine.
Old 03-14-2011, 04:29 PM
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chris6414
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Default RE: OS.61 hard to start

Same here. My old 12V box batt wouldn't start my OS .61 SX-H WC in my Ergo. 2, 3S batts in series and she spins up no problem now. [>:]

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