2008 V150TLR - RPM’s and Speed Lower at WOT


Jan 31, 2023
I have a very reliable and well maintained 2008 Yamaha V150TLR carbed 2 stroke. It starts, idles, and cruises like a champ.

In the last year, it seems no matter what the conditions or weight in the boat, my RPM’s have dropped from 5700 to 5100 at WOT and top speed from 58 mph down to 53 mph average. There is no surging of rpm so it doesn’t look fuel related. I haven’t pulled the carbs and cleaned them yet. That is my next step. I’ve ruled out any hull issues already. All the coils are firing and compression checks out on all 6 cylinders. Sparks plugs look pretty good every time I change them out. Prop looks fine but I may have a prop shop check it out.

What I do notice is that when I push the control forward, RPM’s increase accordingly until I get to about 80%. The control will continue to move forward with no increase in RPM’s or speed. It made me wonder if my throttle linkage needs a looking at. Before I bring it in to my mechanic, I thought I’d try you all for any ideas/ suggestions.

I am not very familiar with the throttle system on this motor, so I attached pics. The only thing I noticed was the nut on the linkage was loose (see pics).

Thanks in advance for any ideas.