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O.S. GF40 4st gas

Old 10-22-2013, 02:00 PM
  #101  
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Originally Posted by indycustombikes View Post
So far I am at 7600 with a 17x8-3 blade xoar prop with this engine but I am still thinking it is rich. I am at 1-1/2 turns out on both low and high needles.... engine has great transition but the plug is still black when checked.... oil is 32:1 lawnboy ashless regular 89 octane fuel.......... should I keep tweeking the high needle until plug is chocolate or leave it as is?

cant wait to maiden my 80" esm p-39 with this engine................ its about 20lbs rtf..............
Please post a flight report with this engine plane combo. I am looking at this engine for a H9 30cc P-47 I am building. That plane is going in around 18 pounds. I have been trying to decide between a dle35, the evolution 40gx, or saving the money and going with the 4stroke sound.
Old 10-22-2013, 02:12 PM
  #102  
TonyBuilder
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Originally Posted by skillet92 View Post
Please post a flight report with this engine plane combo. I am looking at this engine for a H9 30cc P-47 I am building. That plane is going in around 18 pounds. I have been trying to decide between a dle35, the evolution 40gx, or saving the money and going with the 4stroke sound.
Go with the DLE35, the OS40 will fly it but you are going to spend over $900 with a pits muffler, the stock muffler is useless unless you want to cut half the cowl off.

But if you got the coin then by all means the OS40 sounds great and runs great, pulls my 20lb cub around with gusto.

TB
Old 10-22-2013, 03:59 PM
  #103  
indycustombikes
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use a turboheader muffler on the 40 and youll get it in the cowl plus its worth 300 more rpms over stock... sounds great too!
Old 10-26-2013, 04:00 AM
  #104  
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Hope to get a maiden in this sunday if the weather is tolerable..... anyone know where the needle settings ended up with their o.s. 40? I am afraid I have it set lean at 1 1/2 turns on each, runs good though through all transitions on the ground.... I am putting in a new plug for the maiden and will see where the color looks and go from there, I dont think im in danger of too lean territory........ running mix at 32:1 on good ol lawnboy ashless for break in....
Old 10-26-2013, 04:28 AM
  #105  
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Start with the recommended settings, the low is very sensitive once you get 20 or so flights in then lean it out, mine has been flawless with the factory settings and I have over 50 flights logged in, I'm at 8000 rpms on a 18x8 Xoar

TB
Old 10-27-2013, 02:54 PM
  #106  
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Maiden went very well, with the needles both set at 1 1/2 turns out, she idles at 1850 and pulls 7600 static on 17x8-3, the p-39 came in at 20lbs. the 40 pulled it very well and just a tad better than scale, not ballistic but rolls and loops were not a problem...... Now to the engine.... still blowing black soot, sounds rich, after the first flight it turned 7800 static without any needle changes. so I leaned it one screw driver width seemed better, I think this engine is still very rich but with it being a four stroke I am not sure if I should tune it like a two stroke for plug color or not, plug is still very black..... but all in all a great little engine.
Old 10-27-2013, 07:31 PM
  #107  
kerwin50
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I've heard they are having a problem with the exaust lifter shaft. Seems to wear very quickly
Old 10-28-2013, 08:38 AM
  #108  
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Originally Posted by kerwin50 View Post
I've heard they are having a problem with the exaust lifter shaft. Seems to wear very quickly
Please, look here: https://vimeo.com/m/77313341
it is happening in 2-3 hours of operation.
Old 10-28-2013, 09:01 AM
  #109  
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Originally Posted by akouzmit View Post
Please, look here: https://vimeo.com/m/77313341
it is happening in 2-3 hours of operation.
---------
and more with my comments:
https://vimeo.com/m/77297037
Old 11-01-2013, 04:47 PM
  #110  
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Got my muffler today, fits great. I will see how it sounds and performs this weekend.

TB
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Old 11-02-2013, 01:54 AM
  #111  
ozzieflyer
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Originally Posted by TonyBuilder View Post
Got my muffler today, fits great. I will see how it sounds and performs this weekend.

TB
What is that muffler, and where from?
Looks great.
Old 11-02-2013, 04:00 AM
  #112  
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Originally Posted by ozzieflyer View Post
What is that muffler, and where from?
Looks great.
The muffler was made by Kelvin at Keleo Creations. He will be selling this muffler now. This is the first engine to run this muffler so I will report back. It is very solid and I think that all the issue that some four stroke pits mufflers have are not going to be an issue with this muffler. We will see.

TB
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Old 11-02-2013, 10:34 PM
  #113  
sandseeker
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Any feedback on the wear issues from OS or the importers? I am fitting mine to my Aeroworks Cub for initial running/flights, will be fitting the turboheadder exhaust.

Chris
Old 11-06-2013, 07:49 PM
  #114  
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Ran my engine yesterday, no adjustments from the factory settings , great idle. Hope to fly today.

chris
Old 11-07-2013, 06:20 AM
  #115  
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She flys! And v scale like, pity I still have the ugly OS can in the breeze....my turboheader has not arrived yet. The Aeroworks Cub is well powered by this motor and sounds fab.

Chris
Old 11-07-2013, 07:27 AM
  #116  
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http://www.flyinggiants.com/forums/s...=5#post2055300

Please, read this thread regarding GF40 rocker support wear issue.
Once you run engine in the plane for over 3 hour check out exhaust rocker support for wear.
On my engine the wear is 25% of its original diameter.
OS don't want to admit issue.
I am looking for other pilots feedback once the used engine for over 3-4 hours at 75-100% throttle.
Please, look at all videos and photos I put in the thread.
I am experiencing this issue consistently. I replaced rocker support once, and got the same issue in the next 3 hours in operation.
I have a line of SAITO engines: 14c, 17b, 21, 30 and 36 and they all perform very well w/o sign of wear on the rocker site.

Last edited by akouzmit; 11-07-2013 at 07:29 AM.
Old 11-07-2013, 11:57 AM
  #117  
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I will certainly be keeping an eye on this engine, I would send the motor back to OS if I have the same issues that your motor has. Good luck!

Chris
Old 11-07-2013, 02:17 PM
  #118  
indycustombikes
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as best I can tell, after break in we should be looking for a static of around 7000 to 7500 rpm so unloaded in the air it will be in the sweet spot of 8000 to 8200.. I am going to try the 18x10 3 blade next and see where it takes me...
Old 11-07-2013, 02:46 PM
  #119  
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On my GF40 I am using APC 18x8W. On the ground at max throttle I am getting 8000-8100.
Old 11-08-2013, 04:11 AM
  #120  
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I would say that is too much rpms because when unloaded in the air you are right at redline........ could cause premature wear issues... try a 19x8 prop and I bet you would be very pleased with the results.
Old 11-08-2013, 04:28 AM
  #121  
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Originally Posted by indycustombikes View Post
I would say that is too much rpms because when unloaded in the air you are right at redline........ could cause premature wear issues... try a 19x8 prop and I bet you would be very pleased with the results.
I am at about 7800 RPMs and I am using a 18x8 Xoar. I have over 50 flights in and I don't run at full throttle but for a couple seconds at a time. I have no issues and I am planning on a 19x8 too.

TB
Old 11-08-2013, 12:56 PM
  #122  
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I am flying the GF40 on an 80" world P-51. It does a very respectable job and sounds great. I am using a 19-10 Mejzlik that tachs at 7200. I have four flights. The first flight was fine but it killed on landing roll out. I was not able get the engine to run well after. Did not respond to needle changes and backfired throwing the prop. As it turned out, I had the pick-up wire not completely plugged into the ignition. Vibration gave me erratic timing. After completely plugging in the pick-up and a safety it runs great. I am running at 25-1 with the low needle in slightly. I have the high needle out an 1/8 and have not tried to optimize for peak. My rockers are oily and at .003-.004. Does anyone know the OS spec for lash?
Old 11-08-2013, 11:15 PM
  #123  
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I think it is possible that some of us are worrying a bit much about "over revving".

As someone pointed out, most of us don't fly around on full throttle these days. Especially when flying the larger models of the type that this engine would comfortably power.

On the other hand, I don't see the 19x8 as being problematic in the least.

All of this talk about a big four-stroke is making me want to pull out the OS FT-300 that is tucked away down stairs. I wonder who to hire to convert it into a gasoline burner? Or is it a worthwhile modification?

Anyway, that's my slant on it. Just another opinion.


Ed Cregger
Old 11-10-2013, 05:22 AM
  #124  
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Originally Posted by NM2K View Post
I think it is possible that some of us are worrying a bit much about "over revving".

As someone pointed out, most of us don't fly around on full throttle these days. Especially when flying the larger models of the type that this engine would comfortably power.

On the other hand, I don't see the 19x8 as being problematic in the least.



Ed Cregger
I agree. This engine is rated for 9000rpms if I am not mistaken and I am just at 8000rpms. I only go full on take off to gain altitude then small bursts at times but generally I fly at 5000rpms or less. I set up a throttle curve in my radio so I know that at half stick I am at 4000rpms.

TB
Old 11-11-2013, 02:25 PM
  #125  
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Originally Posted by TonyBuilder View Post
Got my muffler today, fits great. I will see how it sounds and performs this weekend.

TB
Hey TB,

Looks good, thanks for the info on the Keleo pitts muffler.
Is that an Aeroworks 50cc Cub that you have the GF40 mounted in?
I plan on mounting this engine in my Aeroworks Stearman 77" and am hoping that at 18lbs it should
have enough grunt to fly it well.

thx
Dave

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