OS FS-70 Ultimate  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       



All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> O.S. Engines Support >> OS FS-70 Ultimate Page: [1]

Login
Message << Older Topic   Newer Topic >>
OS FS-70 Ultimate - 10/25/2004 5:15:42 PM   
anthonymio


 

Posts: 103
Joined: 6/25/2002
From: Scottsdale, AZ, USA
Status: offline 		This summer I purchased an OS FS-70 Ultimate for a T-34 Mentor that I was building. I ran the engine for break-in and could never get a reliable WOT at any needle setting. I sent the engine to Hobby Services and the technician diagnosed it as having a bad pump. The engine was with Hobby Services for two months until the parts and replacement engines were available. I did receive a replacement last week. I started to bench test this new engine yesterday afternoon and unfortunately this new engine also seems to be exhibiting the same problems as the first. It has about six tanks of fuel through it, so before I send it back again, I am hoping that I can get some tips or advise on how to check to see if perhaps I am doing something to aggravate the problem.

Fuel used is Cool Power 15% with an additional 4 oz. of synthetic oil added and all fuel tubing is the “standard” size. Plug is the OS “F” that came with the engine and the prop is an MA 12X8. This is basically how I intend to run this engine when installed on the airplane.

Idle is fine and transition up to and through midrange is also good (idle needle still at factory setting). Midrange run up to 75% throttle is also good, holding approx. 7800 RPM (+/- 50 RPM) on the MA 12X8 at 75% throttle. Needle starts at two full turns and requires to be set at one and a quarter turns to provide the steady run above.

Problems begin when the throttle is advanced to 100%. The engine sags and the RPM drops, indicating an over lean needle setting. Richening the needle a quarter turn produces an overly rich setting with a greater RPM drop, hesitation, lots of white smoke and eventually the engine stops. It seems that there is a very fine high-speed needle range (perhaps 5 or 6 clicks) between an overly lean and rich setting. If the needle is not touched and the throttle is transitioned back down to midrange or idle, the RPMs steady out and the engine continues to run at midrange and back to 75%. I have noticed small bubbles in the line leading to the carb regulator during WOT running; no bubbles were seen between the tank and fuel filter or the fuel filter and the engine. However, I haven’t confirmed that the air bubbles are present in all WOT runs which could be the cause of the top end lean runs. Additionally, it seems I get a good amount of oil being blown out of the crankcase breather. I don’t know if this is normal for this engine and its pump unit.

I am going to run it for a few more tanks, hoping perhaps that it needs to be broken in more. Any help or advise you can provide will be greatly appreciated.

Thanks
       Post #: 1

RE: OS FS-70 Ultimate - 10/26/2004 5:00:42 PM   
Bax


 

Posts: 12634
Joined: 4/26/2002
From: Champaign, IL, USA
Status: offline 		Breaking for a four-stroke engine must be done very, very rich, working towards peak RPM.

With O.S. Max pumped engines, you want to gradually work the full-throttle setting towards peak RPM. You eventually want to be able to lean the engine as far as possible without detonation or RPM drop, and leave it there. Don't lean and then richen, as you'd do with a non-pumped engine. Wherever the needle valve ends up is correct. The actual number of turns is not relevant. You then work on the idle mixture.

Don't be surprised if it takes a gallon or two until the engine has finally "come in". We usually expend nearly a gallon's worth of running before we'll put the engine in an airplane. We want to be absolutely sure it's running right and the settings are found.

_____________________________

Bill Baxter, Manager Hobby Services/Futaba Service/North America
3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
Service Phone: 217 398-0007
Email: hobbyservices@hobbico.com

(in reply to anthonymio)
       Post #: 2

RE: OS FS-70 Ultimate - 10/26/2004 11:37:42 PM   
anthonymio


 

Posts: 103
Joined: 6/25/2002
From: Scottsdale, AZ, USA
Status: offline 		Bax:

Thanks for your reply and advice, however, this FS-70 Ultimate is acting the same as the previous one, which was diagnosed by your technician as having a bad pump/regulator. Bench testing with an additional four tanks of fuel yesterday did not make any full-throttle runs better or more reliable. It continues to exhibit richening at WOT and surges of 500 to 1000 RPM until it quits. Typically within 30 to 60 seconds of the WOT setting. I also get quite a bit of fuel dripping out of the carb throat after it stops. I will be sending this engine back for warranty repair.

(in reply to Bax)
       Post #: 3

RE: OS FS-70 Ultimate - 11/9/2004 10:12:32 PM   
arostosgr


 

Posts: 9
Joined: 3/3/2004
From: , GREECE
Status: offline 		hello there this is my first time writting here. I come from Greece.
I have the following problem:
Beginning at middle throttle i see many bubbles coming from the pump to the carburetor and the engine isn/t getting faster and just quits. The bubbles are not coming from the tank system, as there are no bubbles in that line.
But I had ~20 flights and the engine was the best... At the 21 I had the problem during the flight.
From then the engine has not run again properly...
After half throtle i have the bubles and the engine quits..
I realy thinking go back to the two stroke os engines...
Everything in the engine is good... tank and fuel lines.. also 20% oil in the fuel.
Please realy we need your help if you know anything...
Thanks,Andrew Athanasoulas!

(in reply to anthonymio)
       Post #: 4

RE: OS FS-70 Ultimate - 11/10/2004 3:47:10 PM   
Bax


 

Posts: 12634
Joined: 4/26/2002
From: Champaign, IL, USA
Status: offline 		If you're getting a lot of bubbles between the pump and carburetor, then the pump may be leaking crankcase pressure. You'd have to take it up with your O.S. Max service center for coverage under the warranty.

_____________________________

Bill Baxter, Manager Hobby Services/Futaba Service/North America
3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
Service Phone: 217 398-0007
Email: hobbyservices@hobbico.com

(in reply to arostosgr)
       Post #: 5

RE: OS FS-70 Ultimate - 11/10/2004 11:45:53 PM   
arostosgr


 

Posts: 9
Joined: 3/3/2004
From: , GREECE
Status: offline 		sorry but here in greece is representative for the os one no so good man.. looks only for the money...
if I will tell him the problem he will not do anything.. he has no warranty for the products in his store.
I know that os gives 1 year warranty at all products but he will not do anything.
Please if you have the power inform the os about this.
His name is: Stelios Koutsos and he has the os and futaba for greece. (os know him)
My name Andrew Athanasoulas!
Thank you very much for your time and for your help!

(in reply to Bax)
       Post #: 6

RE: OS FS-70 Ultimate - 11/11/2004 4:42:06 PM   
Bax


 

Posts: 12634
Joined: 4/26/2002
From: Champaign, IL, USA
Status: offline 		Because we're the O.S. service center for North America, there's little we can do to influence O.S. distributors/service centers outside of our service area. Your best bet might be to contact O.S. Max directly:

O.S. Engines
6-15, 3-Chome Imagawa Higashisumiyoshi-ku
Osaka 546
Japan
Telephone: +81 (66) 702-0225
Fax: +81 (66) 704-2722

_____________________________

Bill Baxter, Manager Hobby Services/Futaba Service/North America
3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
Service Phone: 217 398-0007
Email: hobbyservices@hobbico.com

(in reply to arostosgr)
       Post #: 7

Page:   [1]
All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> O.S. Engines Support >> OS FS-70 Ultimate
Page: [1]





Jump to:


Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Member Video Posts | RCU Video Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America

Kaango.com Classifieds

1.016RCU4