2004 Yamaha 150 Two-Stroke Power Loss

[chrisandersen]

On a Seapro CV21, sits in the water, bought in 9/05. Run it about 2-3 times a month in winter to 8-10 in summer. Mostly short trips, idling in and out of channel, no more than 100-150 hours. I have not done any maintenance on the engine.
Recently, I have noticed a lack of RPM's from the engine. It starts and runs fine up to about 3/4' throttle. Past that point the engine will not take the fuel (well, at least there is no increase in boat speed). I also have blue oil leaking out of the cowling.
I am going to pop the hood this afternoon and look to see what is going on and change the plugs.
What else should I be looking for?

 

[chrisandersen]

Re: 2004 Yamaha 150 Two-Stroke Power Loss

Popped the hood and changed the spark plugs. I have attached the old vs new plugs and the overall view of the engine. The oil leak is caused by the secondary reservior spilling over when it is tilted.
Took it for a spin. Started easily, idled well, got on plane faster, but still topped at 4000 rpm and about 26 mph.
Carbs are probably due for a cleaning, but what do you guys think?

 

[drewmitch44]

Re: 2004 Yamaha 150 Two-Stroke Power Loss

For some reason to me it looks like the wrong plug. Just an observation.

 

[rodbolt]

Re: 2004 Yamaha 150 Two-Stroke Power Loss

plug color looks rather normal to me, especially since the maint schedule isnt being used.
myself I would test the compression and rebuild the carbs and replace the fuel pump and keep running. now would be a good time to change any fuel filters on the engine and hull.