Lost RPM

[Major Woods]

Friend lost 800rpm from WOT recently. No change to prop or weight of boat. Engine idels and runs strong all thru rpm range except 800 lower now. Any suggestions on what to look for to correct. 2001 Yamaha 200hp SW. If he can't do a simple fix will have to bring back to dealer, long road trip.

 

[CAPTBLACKSMARINE]

Re: Lost RPM

i would start by hooking a shop tach to the engine and see if it has indeed lost rpm ,has he lost any speed,what shape is the prop in,is the bottom of the boat dirty,how about the fuel filter is it clean?

 

[Fouled Plug]

Re: Lost RPM

Try a compression test and see what it tells you.

 

[JB]

Re: Lost RPM

Ahoy, Major. I wouldn't be a bit surprised if your bud's big yammy is running on 5. <br /><br />Big, multi-cylinder 2 strokes don't lope like a 4 stroke when they drop a cylinder. They sound and seem okay except they are down on power and top end.<br /><br />Inspect the plugs when you pull them to do the comp. check suggested by (interesting!) Fouled Plug..<br /><br />Red sky at night. . .<br />JB