I have 2 old engines, I mean really old, 20 to 25 years old. One is a OS 40SR and the other a magnum
40. I have no paper work and need to know a general procedure of setting the main needle valve
in order to get the engines to start or at least get a few pops. Approx. how many turns out should I use after I have turned the needle all the way in? Also when I am facing the front of the engine does the prop turn clockwise when running? The reason is that I tried to start one and the elec. starter was turning counterclockwise and the prop came loose,even after I felt I had really torked the nut tight. I can use any help out there.

Thanks, Jim

If you are starting with electric starter and spin off prop more than likely you have too much fuel . Try taking out the glow plug and then use your starter to flow excess fuel out (keep your face away from plane when you do this because it usually comes out in a cloud (bad on eye balls). Correct direction is ofcourse counter clockwise facing engine. Close high speed needle and then back out 1-1/2 to 2 turns and try starting from there. The OS should run.

strip them both down and clean them right out before you do anything. also remember these engines where designed for old fuels, castor content is high. this has done two things, saved your engine from dying over time, and in doing that its gummed to hell. i wouldnt point a starter near them till they are shiny new inside

Thank you both, Amazing how we forget the most obvious, 20 to 25 years old engines! You are so correct, GET IN THERE and clean then engines first. That is what I will do first. Again thank for pounding my head.

Jim

Yeah, I have just cleaned up a 20-ish yr old engine of my father's , also an O.S. 40 btw! I can tell you right now , until you can turn it over by hand, and feel the compression of it , don't waste battery using a starter. Once these old engines have run a while they free-up quite significantly.
i know from previous experience with these old engines.

I purchased 25-30 engines {U/C} a while back, like you guys say what a mess ! Get out an old crock pot, put the engines in it and fill up with anti-freeze. Let them cook for 48hours or so, took them out washed them with soap and water then flooded them with oil, and they looked and run like NEW Just an FYI

Throw the Magnum away, I had one of these fifteen years ago, there not worth the effort. It had very little power and barely flew my trainer. The OS, on the other hand, should be a very good engine.

I brought to life two old OS 40 SR (RS?) a couple of months ago. My father bought them some 20 years ago.

They work really nice with 15% byrons fuel and have a lot of power. The needle setting is 1-1/2 to 2