RE: Os 120 4 stroke overhaul help needed  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> RE: Os 120 4 stroke overhaul help needed
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RE: Os 120 4 stroke overhaul help needed - 4/23/2008 7:23:30 PM   
Jaybird


 

Posts: 72
Joined: 7/16/2002
From: Hallowell, ME, USA
Status: offline 		Successful Maiden flight.

After installing the new parts supplied by Neol Jensen and several months of refurbishing, I had a successful test run and first flight of my 20 plus year old BUSA Cub and OS 120. The engine started right up and ran very well. I only had to adjust the low idle setting on my transmitter and a slight highspeed needle adjustment to get a good transition and power. I taxied up and down the grass strip a couple of times and then pointed it into the wind. After a short roll at 3/4 throttle it lifted off and headed up! A few clicks of down trim and it was flying very nicely. Loops and stall turns are very nice and the landings are a non-event with a good idle. I look forward to many years of flying this big bird.

Thanks to all for the help with rebuild and parts.

The engine is a single cylinder but looks like a twin, thanks to the very well built wood dummy engine on the left side of the cowl!


I have a short video of the sart up I'll try post as well.

Jay

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< Message edited by Jaybird -- 4/23/2008 10:15:02 PM >

(in reply to Jaybird)
       Post #: 26

RE: Os 120 4 stroke overhaul help needed - 5/6/2008 2:42:44 PM   
Jaybird


 

Posts: 72
Joined: 7/16/2002
From: Hallowell, ME, USA
Status: offline 		Here is a link to an engine start and flight video.

http://www.rcgroups.com/forums/showthread.php?t=854104

I'm finding that i'm having tuning and run issues as time goes on that are perplexing. I've listed the problems on the video thread. Does anyone know what o-rings there are in the carb and what size?

Jaybird

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(in reply to Jaybird)
       Post #: 27

RE: Os 120 4 stroke overhaul help needed - 5/7/2008 1:58:34 AM   
Ken6PPC


 

Posts: 593
Joined: 6/20/2006
From: Hamilton, OH, USA
Status: offline 		I don't think that your left cylinder is firing at all! <GRIN> Knowing what engine was supposed to be in your plane, I did a double take (pun) when I saw the picture of a twin. That looks VERY nice!

Seriously, your engine sounded like it was running very well in your videos. What happened?

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Club Saito Member #370
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(in reply to Jaybird)
       Post #: 28

RE: Os 120 4 stroke overhaul help needed - 5/7/2008 1:34:39 PM   
Waco Driver



Posts: 157
Joined: 1/16/2003
From: Paris, ON, CANADA
Status: offline 		I have found that a Perry oscillating pump improved the running characteristics greatly on my 2 OS 120 FS engines. No more leaniing out as the fuel level drops.

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MAAC 6273 L

(in reply to Ken6PPC)
       Post #: 29

RE: Os 120 4 stroke overhaul help needed - 5/7/2008 10:31:49 PM   
Jaybird


 

Posts: 72
Joined: 7/16/2002
From: Hallowell, ME, USA
Status: offline 		It was suggested that i try switching from my cool Power 15/18 fuel to 20/20 fuel by a modeler who had the same engine and same problem. It did run great for that video and then started running poorly the next few flights afterward. I'll keep you posted.

Jaybird

(in reply to Waco Driver)
       Post #: 30

RE: Os 120 4 stroke overhaul help needed - 5/8/2008 8:39:39 PM   
Jaybird


 

Posts: 72
Joined: 7/16/2002
From: Hallowell, ME, USA
Status: offline 		I did a quick test run with the new 20/20 fuel and it seemed to like it. it started right up and idled very nicely without any external glow driver. I'll have to continue tuning to make sure it continues to cool enough. It did seem to transition well from idle to full power without loading up as before. What I do still have to contend with is something metalic rubbing somewhere and causing bad intermittent elecrtrical glitching. Not sure where to start. I can duplicate it without the motor running by touching a screwdriver the cylinder head, but that seems typical. I'll keep looking.

Jaybird

(in reply to Jaybird)
       Post #: 31

RE: Os 120 4 stroke overhaul help needed - 5/10/2008 3:31:01 AM   
submikester


 

Posts: 1177
Joined: 8/13/2004
From: El Segundo, CA, USA
Status: online 		Are you running muffler pressure on your 120? I run it with mine and it runs well like that on 15%; I've tried 20% in it but it didn't seem to run as well. I prefer 15% in mine.

Also, I'm using a Zinger 15x6 prop.

(in reply to Jaybird)
       Post #: 32

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