OS 61 "SF"

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TX_QBALL@webtv.net - 06 Apr 2004 00:20 GMT

Anyone have the low and high RPM limits for this engine. It's does ok
from mid to full throttle but the idle is rough and dies.I've adjusted
the low end and just can't find that rite spot.The low end is not like
my other engines.The little offset screw that rocks the plate back and
forth don't have a lot of movement.There's no air leakage. The engine
doesn't have much time on it.Got it and replaced the bearings and low
end adjustment assembly. I put the new one in like the old one came out
but wondering if something is arye. I need to get a tack to see exactly
what r's it's turning but I'd guess around 5000.
Help
Walt

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James D Jones - 06 Apr 2004 15:29 GMT

If you are only getting 5000 RPM, something is wrong. This engine
easily exceeds 12K when properly adjusted. It seems likely that you
are running way too rich. My 61 SFs aall did a "4-stroke" idle at
less than 2000 RPM without difficulty.

I use a 13X6 prop on mine, and it runs great. First adjust the high
end by peaking it lean and backing off abou 300 RPM. To adjust the
idle, use the pinch test. With glow heat on, pinch off the fuel
while it is idling. If the engine speeds up much before quitting,
it's too rich. If it slows and stops, it's too lean. You should
get a small increase in RPM only.

Once adjusted, remove glow heat. If it slows down a great deal, then
you have a bad glow plug.

Jim - AMA 501383 (remove NOSPAM to reply)

> Anyone have the low and high RPM limits for this engine. It's does ok
> from mid to full throttle but the idle is rough and dies.I've
[quoted text clipped - 6 lines]
> to get a tack to see exactly what r's it's turning but I'd guess
> around 5000. Help Walt

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Mike - 06 Apr 2004 16:14 GMT

Good advise Jim.
However your last comment regarding the engine 'slowing when glow power is
removed' should include, in addition to a bad glow plug, possibly bad fuel
.

Happy Flying,
Mike

> If you are only getting 5000 RPM, something is wrong. This engine
> easily exceeds 12K when properly adjusted. It seems likely that you
[quoted text clipped - 23 lines]
> > to get a tack to see exactly what r's it's turning but I'd guess
> > around 5000. Help Walt

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Model Forum / Radio Controlled / Air Models / April 2004

OS 61 "SF"