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11-04-2004 01:43 PM  13 years agoPost 1
frogbaiter

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Oxford UK

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Is there a way of finding/setting the mixture/idle screw back to it's "normal" (factory) position without removing the engine to look down the carb?

I'm trying to get my engine tuned right, I'm not at all happy with the way it's running, and I fear I've got the mixture screw way out of position.

It's producing loads of smoke, the right sort of power, but really doesn't wwant to idle smoothly. At the sort of idle speed I used to have, it stops when the glow power is removed.


Steve
www.helicollective.org.uk

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11-04-2004 03:54 PM  13 years agoPost 2
Darksider

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Derby United Kingdom

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it might be time for a new glow plug, also it's worth mentioning that when the cold weather comes all heli engines seem to take on a slightly rougher idle, i noticed it alot recently as the temperature dropped off, the best method i know to set the low needle without looking down the carb barrel is to get the high needle right by doing climbouts and general flying and check for consistency, then set your throttle hold just right so that your clutch doesn't grip and the engine will keep going once warmed up, note at this setting it may still stop at idle when cold, then shoot afew auto's close enough so that you can hear the engine and how quickly it drops back to idle, the ultimate aim is to have the engine drop back too idle in around 2 - 3 seconds if it take longer it's too lean, if it's shorter the low needle is too rich.

hope this helps

Gareth

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11-04-2004 04:07 PM  13 years agoPost 3
steve69

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Berkshire, UK.

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I was with Frogbaiter at the weekend when his trouble started and I believe he is asking for an easy way to reset the mid range back to stock without having to take the engine out as he was adjusting it quite a bit with little sucsess and wants to put it stock so that he has a known starting point to adjust from.

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11-04-2004 04:17 PM  13 years agoPost 4
Darksider

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Derby United Kingdom

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for the high needle, set it to about 1.5 turns out and then lean from there, as a rough guide the high needle is usually about 1.25 out on 15% nitro and about 4 clicks leaner on 10% most of the time the os 32 is very easy to tune but i know what a pain it can be when you feel you've lost that sweet spot, the main thing to remember with the os 32 carb is that the high needle meters the entire fuel flow, so it's important to set the high needle right first and then work on the low needle last.

Gareth

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11-04-2004 05:31 PM  13 years agoPost 5
frogbaiter

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Oxford UK

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Thanks for that. I just got back from the field (managed three tanks of fuel - nice weather!) and I seem to have got it better now. It certainly ran more comfortably after a little tweak, but it just sounds different, sort of wetter.

I'll bear your advice in mind, Gareth. That might have been my last flight for a week or so, as I'm off on a week's hol on Saturday. When I get back I'll see how it is. I agree about hte weather making a difference, too!

Hey, Steve - I had to take turns at the field today with a tractor that's building a huge bonfire not far from our patch!


Steve
www.helicollective.org.uk

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11-04-2004 06:07 PM  13 years agoPost 6
steve69

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Berkshire, UK.

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Your kidding????

Any other info, will it affect flying this weekend if the weather holds?

Good news on the engine by the way.

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11-04-2004 06:20 PM  13 years agoPost 7
frogbaiter

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Oxford UK

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Dunno about the weekend - perhaps they'll be torching it tomorrow. Certainly won't be during daylight .... unless you were planning nightflying?


Steve
www.helicollective.org.uk

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11-04-2004 07:04 PM  13 years agoPost 8
steve69

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Berkshire, UK.

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I was more worried about a girt big pile of timber sat in the middle of the field all day saterday..... although Ben has been keen on night flying, maybe the fire light will help him out....

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11-04-2004 08:56 PM  13 years agoPost 9
ShempHoward

rrKey Veteran

San Francisco, Ca - too many beggars + bad drivers

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There is another way to get the low end needle set close to where it should be but this method also will require some trial and error but still it will get you close. Its an old trick used by plank flyers. Pull off the fuel line to the carb at the inlet nipple and attach a new/unsued piece about 12" or so in length. Close the throttle down all the way and try to blow air thru the tube. If you get little or no air movement then try opening the low end up just a touch until to hear a hiss then set the high end where you normally fly and and then try blowing again with your thottle trim in what you feel is the normal setting for an idle. Now adjust the low end up/down while blowing thru it so you get a mild hiss while blowing but still get a bit of resistance. This should get you in the ball park and be fairly cliose if not spot on. Keep in mind that the OS factory settings on the low end is usually a bit too rich onall their engine offerings. If you start your Heli and the engine has a tendency to run backwards you're a bit too rich on the low end. If you start it and it immediately dies without any burbling/hesitation while advancing the throttle your likely too lean on the low end. If it burbles/hesitates when applying throttle to spool up and it then dies your still a bit too rich.

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11-04-2004 09:00 PM  13 years agoPost 10
frogbaiter

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Oxford UK

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Shemp - that sounds a useful way to go, thanks!

Steve - it's an interesting obstacle to avoid - even more so if it's alight!


Steve
www.helicollective.org.uk

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11-05-2004 12:58 AM  13 years agoPost 11
Aaron29

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USA

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..
..

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11-05-2004 08:56 AM  13 years agoPost 12
ShempHoward

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San Francisco, Ca - too many beggars + bad drivers

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How could you call it a Hover Mixture needle?? Most of us Hover at half stick. The two needles interact with each other to a degree but once you are at Hover the bottom end is less significant.

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11-05-2004 01:41 PM  13 years agoPost 13
Aaron29

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USA

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..

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11-08-2004 02:01 PM  13 years agoPost 14
dsmit258

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Knoxville, TN

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Aaron29,

Just wanted to say that I really appreciate your reply to this thread. I thought I had my OS37 dialed in - no way! I went back and set it just as you described, adjusting the low end needle for HOVER instead of idle. I could not be happier with the results!! This thing rocks now - smooth as silk!!

Thanks again,

David Smith

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