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OS 120 E four stroke Engine

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tigerman10/08/2018 16:20:42
121 forum posts

Need a new good 120 four stroke engine .My favourite four stoke engines are almost hard to obtain and are always out of stock so I will have to find a replacement and OS are the next best engines but it looks like OS no longer do a 120 four stoke but I see there are a few OS 120 E four stokes available still, just wonder what they are like ?

Jon - Laser Engines10/08/2018 18:06:54
4019 forum posts
154 photos

The 120E is similar to the original surpass and is a good general purpose engine but its no power house. The exhaust supplied is also small and loud so will need replacement if you have a noise limit at your site.

Beyond that they are good engines. A friend has the pumped version but its effectively a 120E as the pump gave up the ghost and its now got a standard asp120 carb on it. It runs a 15x8 prop in the 8300-8500 range and powered his 70 inch spit quite nicely.

If you can find a non pumped surpass III you will be better off but they are pretty spendy if I recall.

tigerman10/08/2018 19:52:54
121 forum posts

The other 120 four stroke someone suggested was the ASP 120 but I thought this was a budget type engine and not sure of the quality of this engine but I could be wrong

Don Fry10/08/2018 21:02:35
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2615 forum posts
30 photos

You are wrong. Nice motor.

Percy Verance10/08/2018 22:07:33
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6961 forum posts
140 photos

About 10 years ago I bought an ASP .61 four stroke simply to find out how they perform. I fitted the engine to a model and flew in relentlessly. Ok, after a couple of years of solid regular flying it was beginning to show the early signs of getting slightly tired, but as far as the actual running and throttling went, an OS couldn't have done better........

ASP spares prices are very reasonable, so a refurb wouldn't cost a fortune unlike an OS......

Bob Cotsford10/08/2018 22:10:35
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7442 forum posts
420 photos

The ASP 120 is a good engine but from my experiences with that and one of the OS's, the OS will beat it both on output and carburation. My OS would turn a 16*8 APC quite happily while my ASPs were better on 15*8, the OS was easy to tune for a smooth throttle action, the ASPs were harder to setup for a smooth midrange transition. The ASPs were still very good engines just not as refined as the OS.

John Duncker10/08/2018 23:26:57
22 forum posts
7 photos

Saito 125s are available of the shelf AFAIK.

Not cheap though but quality rarely is.

Jon - Laser Engines11/08/2018 02:10:07
4019 forum posts
154 photos
Posted by tigerman on 10/08/2018 19:52:54:

The other 120 four stroke someone suggested was the ASP 120 but I thought this was a budget type engine and not sure of the quality of this engine but I could be wrong

If you want it to last for ever, has great performance/quality and a nice finish then its the wrong motor. if you want an inexpensive power plant that works and you throw away when past its best then crack on.

Just ignore the ASP run in instructions, there is a better way to do it.

Alve Hansson04/09/2018 18:53:50
28 forum posts
6 photos

*

Edited By Alve Hansson on 04/09/2018 19:01:06

Paul Marsh04/09/2018 19:43:30
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3375 forum posts
929 photos

The ASP/SC/Magnum 120's are all ok, they last years, but haven't got the power of an OS. In fact the same is said to all the engines, but powerful enough for most things, good value and spares are cheap, compared to OS.

But the OS 120, especially the pump is a powerful beast, really powerful.One OS120 FS pump is 30 years old - had a new set of bearings 10 years ago and still going.

Even now. on a 16x8 3 blade prop, I'm getting over 9000 rpm on it, it goes through the sound barrier - people can testify to anyone whos seen my Chris Foss Extra Wot go.

In comparison a SC/ASP 120 FS with a 15x8 3 blade prop goes no-where near - and that's a smaller prop. But for the price it does it's job.

alex nicol04/09/2018 20:10:42
132 forum posts
4 photos

if power and price are issues, then you could always go for the asp 1.80, there's not a lot of difference in weight and it's the same crankcase as the 1.20.......... more importantly it'll swing a 16x8 effortlessly

I have one in the front of a Flair Christen Eagle (not the lightest airframe on the planet) and it will go vertically out of sight.

there's a review on the JE website and it's spot on .......That's my two peneth worth.........good luck with your search

Cuban804/09/2018 20:31:43
2108 forum posts
4 photos

I have several ASP four strokes and for what I paid for them new, they were good value for money and have served me well. Not as powerful as the OS and the quality of the carburettors is variable, tend to wear quickly so do give tuning issues and are no where near the standard of manufacture of the OS. Providing one accepted these things then no problem, given the engines were near half the price of an equivalent OS some years back.

I have just bought a NIB OS120 E for my BT Spitfire Mk1a - cost me £200 and had to wait for a good one to appear on BMFA but the difference in quality is obvious - the engine is so much more powerful, smoother and economical than my ASP120fs, both run on Laser 5% fuel. Pulls the 14lb Spit around with authority. I still have a NIB ASP 91fs for another project underway at the moment, but I wouldn't buy another new one, they're not the good value anymore for what they are IMHO, which is a pity. The Saitos seem nice but I understand they need at least 10% nitro, which I'm not keen on - are they actually OK on 5% nitro?

Noted Alex's comment on the 180 - a club mate has one and it does perform......but boy does it drink fuel if you use its performance.

Edited By Cuban8 on 04/09/2018 20:36:51

Bruce Collinson04/09/2018 21:51:18
111 forum posts

Bought a NIB Saito 72 at the last club auction, still with a gratifyingly big price tag on it. Took a chance on it at the front of an ancient DSM Excelsior 150 which incidentally is a sweetie. Even I can fly it.

The Saito sect advised 15% nitro and it ran and flew but it was hard to tune, after about an hour’s running. The sub-sect prescribed an OS 4 plug instead of the Saito and a tank of Laser 5.

Starts easily, 2 clicks of throttle, holds its tune, idles ok and it’s £10 a gallon cheaper.

Still very oily though. Maybe it’s the more modern Saitos which prefer more nitro.

Hope this helps.

BTC

supertigrefan04/09/2018 22:03:35
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292 forum posts
7 photos
Posted by tigerman on 10/08/2018 19:52:54:

The other 120 four stroke someone suggested was the ASP 120 but I thought this was a budget type engine and not sure of the quality of this engine but I could be wrong

Yep, it's a budget engine especially when compared to OS and Saito.

Jon - Laser Engines04/09/2018 23:16:59
4019 forum posts
154 photos

Don't forget enya. if you can find a 120R they are savage monsters. Not especially refined I would say, but power in spades.

john stones 104/09/2018 23:44:16
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9887 forum posts
1472 photos

Yep I like Enya, love the sound of em, plenty Y.S about at good prices as well.

Bruce Collinson07/09/2018 13:19:36
111 forum posts

Jon,

What's the better way to run in an ASP?

BTC

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