Engine R.P.M.
 

I Have a 120fs pre surpass engine with twin valve covers. I am using wildcat 10% syn fuel with a 15x8 prop. I can only get 7300rpm. Should it be running higher rpms than that?

Thanks, wings nh.

Engine R.P.M.
 

Wings,

The old non-Surpass FS-120 should turn a 15 x 8 propeller somewhere in the 8,000's when it's running in its prime.

Your engine may have a worn piston/ring/cylinder fit, or leaking valves. Unfortunately, parts for that engine are very scarce, and not available from the service center or O.S., in Japan.