Yamaha 200 Four Stroke

[Fish Junky]

Hello All,

I have a 2007 Yamaha 200 hp Four Stroke on a 21 ft North River Seahawk. The motor runs great and all but I noticed that I lost 7 miles an hour off my top end speed. I haven't added any weight or changed anything. The motor runs normal other than the speed. I first thought it might be the prop. I took it to a prop shop where they ran all kind of test on it. The hub and everthing was good as new. The RPM's are running about 5700. Also since new I have been good about keeping up with all the services. Now one thing that comes to mind, Does the valves need to be ajusted. The motor currently has 183 hrs. I ask the shop if they need to be done when I took it in for the 100 hr service. I was told no. 97 % of the time I just keep it around 28 to 30 miles and hour and don't try to hot rod it.

I forgot to add after break in the top end was 47 miles and hour. I'am now only getting up to 38 to 40 mph. I also have 3 friends with the same boats and the same motor. After talking to them they are reaching 47. I'am no speed demon but I do fish alot of high elevation lake where I'am also seeing the problem.

I will be very thankfull for any info.

 

[rodbolt]

Re: Yamaha 200 Four Stroke

at higher elevations the fuel mix tries to lean out to correct for it.
but if the engine still turns 5700 like it always did I would suspect a hull issue or a speedo problem.

 

[Fish Junky]

Re: Yamaha 200 Four Stroke

Thanks for the response Rodbolt. Most of the time I fish close to sea level. This problem has me stumped.