OS MAX 20 R/C Help

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Chris H - 25 Sep 2004 04:30 GMT

Hi,

I recently bought a rc gas boat and can get it started, but one it
dies, I'm forever un flooding it until it finallys starts again. The
motor is brand new but the instructions dont say how many turns to
turn the needle valve, or the air bleed. So I've been pulling my hair
out just trying to get this thing started. Currently the needle valve
is set to about 1 turn out, and starts with about 1/3 throttle. At
the moment I can get it started again, but I've had it started a few
times today.

Thanks in advance,

Chris.

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Boat Hull Maker - 25 Sep 2004 11:33 GMT

I should be 2 to 3 turn, depend on the different nitromethane %. If 0%
nitromethane, approximately 2.25 turn. As the nitromethane % increase, turn
out the needle valve more. Accurate needle valve setting can be obtained by
testing only. Normally start your motor at a rich setting, gradually reduce
the number of turn. Most r/c carb. has an idle mixture control valve, need
adjusting too.

> Hi,
>
[quoted text clipped - 10 lines]
>
> Chris.

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Chris H - 26 Sep 2004 08:57 GMT

> I should be 2 to 3 turn, depend on the different nitromethane %. If 0%
> nitromethane, approximately 2.25 turn. As the nitromethane % increase, turn
[quoted text clipped - 17 lines]
> >
> > Chris.

I bought a new glow plug and had the boat running today for a good 20
minutes in the water. I'm running it 1 turn out and even that is
rich. It rev's slow and if I turn it out to 2 turns, it bogs down
when giving it more then half throttle. Is it possible that my needle
valve is different and o
nly needs to be a few turns out? Should i screw in the air bleed and
turn out the needle valve? I'm lost here... the boat runs great,
starts easy, idles nice, but its only 1 turn out. Its definatly
running rich, by the smoke it blows, and the way it revs.

Any ideas?

Cheers,
Chris.

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Boat Hull Maker - 26 Sep 2004 10:44 GMT

> I bought a new glow plug and had the boat running today for a good 20
> minutes in the water. I'm running it 1 turn out and even that is
[quoted text clipped - 10 lines]
> Cheers,
> Chris.

The problem is likely NOT the needle valve setting. It seems the loading is
too heavy or nitromethane content is too low, would you tell me how many %
nitromethane. Either use smaller prop. (smaller pitch and/or smaller
diameter) or increase the nitromethane %. Use only glow plugs that match
you engine characteristic(plug temperature and maximum power rpm matching).
If your engine is OS 20 FP, the performance you got was normal, 20 FP is not
a strong engine.

Don't know meaning of air bleed.

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Chris H - 03 Oct 2004 05:36 GMT

> > I bought a new glow plug and had the boat running today for a good 20
> > minutes in the water. I'm running it 1 turn out and even that is
[quoted text clipped - 20 lines]
>
> Don't know meaning of air bleed.

ok the boat is running great. I put a bigger prop on it and it flys
now. Its still running rich and wont rev much over 3/4 throttle. The
prop it came with was WAY too small. The valve is still 1 turn out.
The air bleed is the little screw that is on the opposite side of the
needle valve. I thought it was called the air bleed? Or is that my
low speed setting? And the needle valve is the high speed setting?

cheers,
heb.

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Kevin - 03 Oct 2004 15:30 GMT

Try emailing The OS distributor at:

enginesupport@greatplanes.com

They also PDF versions of the current manuals at:

http://www.osengines.com/manuals/index.html

OR you can order photocopies from them.

> > > I bought a new glow plug and had the boat running today for a good 20
> > > minutes in the water. I'm running it 1 turn out and even that is
[quoted text clipped - 32 lines]
> cheers,
> heb.

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Model Forum / Radio Controlled / Water Models / October 2004

OS MAX 20 R/C Help