im_a_rcav8r

I am getting an os fs-120 4 stroke that will start, idle, and transition well to about 3/4 open throttle. If I go wide open it dies. I got this engine for way cheap because of this. I am hopping it is just a bad gasket or valve adjustment. Has any one had this kind of problem with an os 4 stroke? What could the problem be?

staggerwing

My Feedback: (5)

Sounds like it's too lean to me. Open up the high speed needle a click or two. Make sure that you are using at least 15% fuel.

paladin

My Feedback: (9)

im_a, I have a Saito that came with the intake valve tapiz so tight that the valve never completely shut. Mine would run rough at all speeds but the higher I put the throttle thr rougher it got till it would quit or backfire through the carb. I ended up going through this a number of times because the spring had som memory so after running it , and it exhibited the same symptoms (only I got further up the throttle curve), and everything would be tight again. I'ld reset the valve gap and run again only to have the same problem. finally last winter I decided to back the tapiz way off and lieve it for the winter. I've reset the tapiz and hope to get it out soon to see if it is finally fixed.

Sounds like you may have the same problem only on the exhust end.

Good Luck

Joe Felice