9.8hp not getting to full speed

[matthopp]

I have a minimally used 1975 (i think)mercury 9.8hp 110. The motor was given to me from friend who rarely used it, we presume it has less than 30 hours on it. It sat for a long time in a garage. It starts and runs great, but only maxes out at about half speed (still running great). It just doesnt go any faster once you reach about half throttle. It doesnt foul or die, just maxes out no where close to 9.8hp. Any ideas?

 

[Fouled Plug]

Re: 9.8hp not getting to full speed

I'd start with cleaning the carb, if you haven't done so already. Could be a bit of crud keeping you from WOT. Make sure both plugs are sparking, and test compression if you can. And change the lower unit lube while you've got the tools out.