barkin_bob

I just bought a old fs-90 that seams to have a few good mile's left in her. What I need to know is where to start with both needle valve settings, valve clearance's, recommended prop range, and fuel recommendation and last will the #F plug work well with this motor. Thanks for any help..... Bob P.S. I've been to the OS web site and they don't offer the manual down load for this old engine.

Bax

My Feedback: (11)

For the old FS-90, start out with the high-speed needle about 3 turns out and the idle mixture known rich. You'll need to start at part throttle and get the full-throttle setting found first, then retard the throttle and get the idle mixture set.

We'd use a 13 x 6 or a 12 x 7 or 8 to start. Prop it so it's running high 8's to low 9's.

The valves set just like any other O.S. four-stroke engine. Please see the O.S. FAQ page.

Use an O.S. Max Type F plug. You can use any regular two-stroke fuel of 10%-15%, or a four-stroke fuel with the same nitro content.