berge

Could you please advise what could be causeing this problem,My os 92 4 strokestarts and runs very good except the revs drop at full open throttle . When I reduce throttle to about three quarter open the revs peak to about 9200 rpmand the motor runs smooth. The pick up from idel is good and range of revs is good up to three quarter throttle,but when stick is moved beyond this to full open the motor falters a little and peak revs drop. I have made minor alteration to bottom end without success. The needle setting is 2 turns out and running 14x7 apc prop. Looking forward to your reply. Thanking You Glenn

Bax

My Feedback: (11)

It sounds like the engine just isn't getting enough fuel. You may want to reset the carburetor. Start out with the idle mixture set much, much too rich. Set the high-speed needle at a very rich setting, 3 turns or so. Start the engine at part throttle and then open the throttle to full. Do not remove the glow plug battery yet.

Adjust the high-speed mixture until the engine is running at peak RPM. Then richen it slightly. If the engine will sustain running "all day" when leaned to just rich of peak RPM, then it's broken-in enough to idle. Retard the throttle and adjust the idle mixture as needed to keep it running well. Because you know the idle mixture was purposely set very rich, you know it will have to be leaned.

By working with the idle RPM and mixture, you can eventually find the proper setting for a good idle. Lower is better, but only if you have a good throttle transition. Any idle below 2,200-2,500 RPM is good.

berge

Thank you for your responce