I am fairly new to the hobby as most of you know, I was surprised to see that os had a four stroke engine on the market back in the late 80s. When did they come out? I always thougt the fs was a fairly new thing. Guess I should have paid more attention! One would think the fs engines would be cheaper since they have been on the market for 20 plus years. They must have been really expensive back then!

I am not sure when they came out with four cycles, but they were out before that. Some of the first were low on power. It will be interesting to see when they did come on the market. Do you have one, and if so what is it?
I don't think the price has come up that much, seems like I paid about $100 for my first saito .50 and that was back in the early 80's.

The OS FS 60 came out in 1976.

No, I dont have one, just was surfing u-tube as saw a vid from 88 with an os 61 fs and was just surprised, I had not even heard of a FS engine until a few years ago, but then I was not "in the hobby" at that time, was still wishing then. Still wishing for a FS engine for my cub tho, just cant beat the sound!

Wow! I guess I have been living under a rock! the engine is only 2 years younger than me! Learn something new everyday................sheesh, glad I didnt get into a debate with someone about this subject! I would have proven my ignorance!

We receintly had one of our more senior club members bring in his engine collection. He had some single cylinder as well as 5 and 6 cylinder radial 4 stroke engines from the 40s and 50s. They were hand made by a guy in up-state New York. Some of them even had true spark plugs and distributor cap/point setups. Not very reliable from what I understand, but very impressive for their time. For my money, I go with Saito. You get a reliable, quality engine without paying for the OS name. Not that OS isn't a good engine, but for 10-20% less you can get the same size and quality Saito. All of my 2 strokes are OS. As to why they are so expensive - a lot of small moving parts with tight tolerances. Take a 2 stroke 90 size apart and set it next to a 4 stroke 90 size. 5 times the parts and work go into making a 4 stroke.

Four strokes were around long before OS but it was rare to ever see one. OS just got out the first good production model. Between the Saitos and OS engines I haven't seen a nickles worth of difference as far as the power or quality and right now the prices are about the same. I like pumps on my engines so that leaves Saito out completely, they have no pumped engines. Price for price I have gone over to YS engines several years ago so that leaves out Saito and OS.

I have one, OS FS 60. I purchased it 1976 from a hobby shop in Pittsburgh for $146, which was a lot of money then. Never was much good - low power output - and so was retired very early.

some info on OS engines dating from 1936 http://www.osengines.com/history/ostimeline01.html looks like 1976 was the first OS 4stroke

The old OS FS60 does pretty nice in a casual Sig LT40 trainer type plane

I like the way you used the term casual!!

I'm retired but there was a much older guy than I am showed up at the field with a FS60 on a kit built LT40. It idled so nice & low. It had about the right power for a leisurely flight. The guy came in too high to land and the LT40 went 100yds before it stopped and appeared to go in the weeds. The elderly gentleman went to get it. When he returned, he was mad at us for not telling him it was still running. We couldn't hear it either.