VeeAte

I got given a second hand motor the other day by someone who has moved onto large scale gas engines.
The motor from what I can tell is an OS Surpass 70 FS.
Having looked through the threads here on RCU the only OS 70 I can find mention of is a Surpass II.
These all have a black rocker cover.
Mine has a chrome rocker cover on it.

Just wondering if anyone knows the difference between the two or if there is any difference?

Also I was told it will fit in most .40 2 stroke sized planes, but the case looks as big as my new ASP .91 FSAR.

Anyone have any info on the OS engine?

gunfighterII

Might be a FS-70S from 1988,

http://www.osengines.com/history/ostimeline14.html

togatoga

My Feedback: (42)

You have the fs70 surpass 1.The 70 surpass 1 is similar to the surpass 2 except for the surpass2, the breather is channeled to the inlet manifold, the bearings are more corrosion resistant, the crankshaft and camshaft is corrosion treated,carb is different and it has a black rocker cover as you may already know.
Power wise, they are about the same ,producing 1.1hp.

VeeAte

That makes sense TogaToga. This engine was left for a while (couple of years) without having after run oil in it. The crankshaft and bearings are a mess. I couldn't get the cam cover off it to inspect that but I guess it would be pretty shocking.

The guy I got it off gave it to me because I built him a website for his business.
He also gave me a brand new in box ASP .91 FS series 3. These engines are identical to the OS motors. The rocker covers even fit.
The rockers themselves look a lot more beefy on the ASP. But then as the OS was old I am sure OS have changed theirs or theirs are fine.

I am sending the 70 back and he is going to send me another motor and some other bits.

Heres a pic of the insides.

Gringo Flyer

My Feedback: (18)

The 70-90 size 4 strokes are pretty close in case size (and most the time not far off in weight either). I have a 72 4 stroke but find that 90% of the time the 91 will work and give a little more power.

VeeAte

Ok cool.
Thanks Gringo.

Appreciate your help and advice.

ggale

My Feedback: (6)

I have two of these (70 surpass 1). One was new when I got it, and the other was a mess as yoursis. I took the messy one apart, soaked it with penetrating oil for a couple of days, put it back together and it has run like a champ for four years. These are excellent engines, and yes, they do fit most 40 size planes. I have one in my new pulse xt 40.

VeeAte

Thanks ggale. I spoke to the guy who gave it to me and he is going to send me another one he has in better nick.
I am unable to remove the lifters or the cam cover and it was for a job I did for him so I just cant be bothered mucking around with it.

I have an Ultimate 40 bipe which needs an engine so thats where the other engine will be going.

ggale

My Feedback: (6)

I am not a pure OS fan, for I think they can be to pricey. But these 70s are nice, whenever a modeler can get one at a decent price, its well worth it. I also have thundertiger, and magnum engines and find them to be great also. the 70 will pull the unltimate with power to spare. it may not show the "hp" numbers, but it has torqe to spare. I usw a 13X6 prop on both of mine.

VeeAte

Yeh I would keep this one, but I can't get the gudgeon pin out to remove the conrod so I can remove the bearings.

If I were able to do that I would keep it. As it's not hard to swap bearings over.

The sleeve has next to no wear on it. You can still see the cross hatch in the bore. The top of the exhaust valve has next to no carbon build up. I dont think its been run much at all.
The rocker gear was not rusted at all.

I cant get the cam cover or lifters out either, but this may just be because of some gummed up oil in the lifter bores.