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O.S. 56 alpha four stroke

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Maurice Dyer19/08/2019 16:27:10
61 forum posts

Somebody selling a 52 has tried to convince me there is a oil lubrication problem with the 56 four stroke. I've got one and it's running ok on 17% synthetic. Anybody heard of any problems with the O.S. 56 ???



Denis Watkins19/08/2019 16:38:49
4054 forum posts
75 photos

Most 4 strokes can run a bit dry under the rocker cover Maurice

So a seasonal oiling in that area will benefit the motor, or more frequent in a good flying season

Not OS especially, all your 4 strokes

Jon - Laser Engines19/08/2019 16:47:03
5067 forum posts
217 photos

The OS 56 alpha (and others in that range) had an oil re-circulation system that took waste oil from the crankcase and shot it up the pushrod tube, into the rocker cover, and then through a hole in the intake and back into the combustion chamber again.

The new versions of the Alpha range (with a black rocker cover) have done away with this and gone back to a simple crankcase breather like the 52 and most other 4 strokes on the market.

All things being equal your 17% oil fuel will be more than adequate for any model 4 stroke of the last 25 years and you would most likely be fine as low as 10% oil. Personally i would use 5% nitro 15% oil fuel and just forget it.

Denis makes a valid point about rocker cover oiling but this is not required on the blue topped OS Alpha engines or on any of the Laser range as they both get their oil through normal running.

Maurice Dyer20/08/2019 17:17:11
61 forum posts

Thank you Denis and Jon. I have been running O.S. Four strokes for twenty years and did wonder. And Jon, I had a long chat with Dave Watts of Southern Model Craft at Cosford and long story short, he has put me up a batch of 5% nitro, 12% synthetic and 3% castor to try on my four strokes. I think you are pretty spot on with oil content in four strokes. I was running Dave's 5%nitro 15% synthetic with 2% castor and oil was still flooding out of my engines.



Cuban820/08/2019 20:53:43
2831 forum posts
1 photos

I wouldn't have bothered with the 3% devil's venom (sorry, castor). Taking a lead from Jon, I've been running all of my fourstrokes ASPs and OSs on Laser 5% 15% synth for a couple of years now. No problems at all, cleaner engines and cleaner models - I honestly think you should break the castor habit in modern engines - I think the dash of castor is supposed to be there in case of a 'lean run'? Modelling folk lore? Probably a grain of truth from the old days.wink


Edited By Cuban8 on 20/08/2019 20:57:14

Jon - Laser Engines20/08/2019 21:20:00
5067 forum posts
217 photos

I agree. Castor is dead and you really dont need it any more. While not such an issue in a small 50 class engine, in a larger 4 stroke it just turns to carbon and makes a right old mess.

In testing i have run Laser 4 strokes on oil ratios as low as 5%. Our petrol developments run on 1% in glow terms and my .21 2 stroke nitro car engine runs at the best part of 30000rpm on 10% synthetic oil in one of the harshest environments an engine can imagine.

With all that in mind, 15% synthetic is the maximum oil i would ever recommend to anyone for any glow engine from the last 30 years.

Cuban821/08/2019 07:55:18
2831 forum posts
1 photos

I'd be very happy to run my fleet on 12% oil, with a view to reducing to a nice round figure of 10%. I haven't looked this up, but I think Model Technics do produce a fuel with lower oil content, but using EDL..............years ago, an experienced member of the modelling trade told me that EDL stood for "Extremely Dubious Lubricant"laugh.

Put me off the stuff for life, unjustly, perhaps?

Jon - Laser Engines21/08/2019 08:32:55
5067 forum posts
217 photos

The problem is Cuban most of us are often pretty stuck in our ways. In many respects this is worse with experienced guys as they have their way of doing things and have been doing so for such a long time than anything new tends to rock their apple cart.

Just look at my posts on the forum regarding fuel, running in, and the nonsense nose up test. I am met with a boat load of opposition every time despite what i do for a living and the slim chance i actually know what i am talking about.

Maurice Dyer21/08/2019 14:04:06
61 forum posts

Jon, I would be very interested to read your posts, but thickly here can't find 'em. Would some kind soil point me in the right direction please.??



RC Plane Flyer21/08/2019 14:11:34
675 forum posts
19 photos

Maurice just click on 4724 forum post under Jons name

Jon - Laser Engines21/08/2019 17:00:06
5067 forum posts
217 photos
Posted by RC Plane Flyer on 21/08/2019 14:11:34:

Maurice just click on 4724 forum post under Jons name


Good grief is it that many surprise

In any case, it might be worth dealing with questions you might have from a clean slate as many of the posts are buried in long and drawn out threads. 

Edited By Jon - Laser Engines on 21/08/2019 17:00:59

Maurice Dyer22/08/2019 06:41:50
61 forum posts

Jon, spent ages reading posts: so what s the deal about nonsense no up full power testing??

Apologies. For the pester.....


Maurice Dyer22/08/2019 06:43:08
61 forum posts

Damn iPad. That's Nose up test!!!

Ron Gray22/08/2019 06:51:39
1604 forum posts
394 photos

Oh dear, the lid is off that can of worms, I’ll watch from a distance!!!!

PS I support Jon on this one.

Josip Vrandecic -Mes22/08/2019 10:49:27
2993 forum posts
260 photos
For everyone, including older models of O.S. , 2 and 4 stroke engines, use synthetic oil with the addition of nitromethane without  a hitch . The case you are talking about is probably related to errors in engine exploitation design or previous stock damage. O.S. are the best RC flying drive products ... but expensive. AMEN.

Edited By Josip Vrandecic -Mes on 22/08/2019 10:52:39

Edited By Josip Vrandecic -Mes on 22/08/2019 10:54:34

Jon - Laser Engines22/08/2019 13:08:41
5067 forum posts
217 photos
Posted by Maurice Dyer on 22/08/2019 06:41:50:

Jon, spent ages reading posts: so what s the deal about nonsense no up full power testing??

Apologies. For the pester.....



During the flight the model will never be dead vertical, at full power, and not moving forwards all at the same time.

Even during a loop or other vertical flight at full power the model will fly at probably 15-20mph minimum and this airflow is sufficient to unload the engine so the test is not representative of flight conditions.

As the engine unloads it runs slightly richer and this is more than enough to offset the additional drag on the fuel caused by gravity when climbing.

For those who doubt the fact that it runs rich when unloaded fit a prop, tune engine, fit another prop 1 inch bigger and you will most likely find its now running lean and wont hold full power. Re tune it, put the smaller prop back on...oh look, you can lean it off a shade more now.

There are exceptions to the above. Anything with a tuned pipe needs different treatment, 3d models might find slightly richer mix an advantage, and engines that wind up massively on rpm (like pylon racers etc) again have different rules. For non exotic fixed wing engines used in sport/scale models you can ignore it all. Just tune for max power and fly.

If the engine then lets you down after a few minutes and stops then you likely have a fuel tank position issue, or a cooling issue and these can be diagnosed in other ways.

I hope this helps. If you have more questions Maurice i am happy to answer them but i wont be entertaining another long argument on this subject so will not be getting into a mud slinging match with anyone else.

Jon - Laser Engines22/08/2019 13:09:21
5067 forum posts
217 photos
Posted by Josip Vrandecic -Mes on 22/08/2019 10:49:27:
O.S. are the best RC flying drive products


Right through the heart broken heart crying

smile p

Edited By Jon - Laser Engines on 22/08/2019 13:09:39

Peter Christy22/08/2019 14:11:37
1666 forum posts

OS engines may be OK, but I don't like their carburetors! I always found them excessively fiddly to set up, right from my earliest Max 40 to my 70SXH heli engine. I've NEVER managed to get the latter to behave properly at all times!

Luckily, I have very few OS engines! Lots of Super-Tigres and German Webras (before they moved production to Austria). Indeed I have a Webra 61 that is now 50 years old, bought new, and still hauling a large, vintage aerobatic model around in style!

It will probably out-last me!



Nigel R23/08/2019 10:03:18
3394 forum posts
524 photos

Have to disagree there, I always found OS carbs generally straightforward to tune, old crossflow Max H 40 included.

Obviously Laser carbs are better smiley

Denis Watkins23/08/2019 10:39:38
4054 forum posts
75 photos

Any I/C motor; you have to respect the engineers and designers that produce a throbbing, pulsing artefact

From a lump of aluminium and steel.

And to boot, they will run from approx 2000 - 10000 rpm, without adjustable timing.

Am in awe of these chaps, each time I take one to the air

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