RPM Problem please help!!!

[levec]

Hi . Help me about my engine.
Its Mariner 40 hp 2 stroke and i have problem with running, he goes good until 5000 rpm and the last 1/4 of gas to 5500 rpm doesn't go.
I change everything from the fuel system but its the same problem. The mechanic told me that the problem is reed valves. its can be or not. Thank you very much.

 

[Sea Rider]

You have engine installed on which type of boat ? Is 40 HP max transom rated for ?If with huge hull drag going 3/4 to full throttle won't see much speed improvement, probably need a prop maximization. When reed valves are kaput you will have erratic idle issues not issues at speed.

You need to tach that motor with an induction Tiny Tach or Hardline to check max wot rpm achieved at wot to see if inside safe numbers for that HP engine. You could be lugging the engine at WOT and not know nothing about it.

Happy Boating