90 hp -1999 top end power decrease

[BugEyes]

Hi all,

I have the above engine on my boat.

I bought the boat used with the engine on last year and I have run it one season. Last year in the beginning of the season I would get a top speed of 34 knots but at the end of the season I could not get past 31 knots.
The seller claimed 37 knots on GPS but I have not been able to get close to that.

Now that the boat is on land and getting ready for this season I thought I might get tips on what to check as it for some reason seems to loose top end power over time. The bottom was clean when I took the boat out of the water so that's not the problem.

Last year I changed the plugs, gear oil and impeller and that is all I have done with it yet. The old impeller was intact and the mill shows no sign of ever having been overheated.

Low end and idle is very good and i have no problems in cruising speed (23-25 knots), just seem to gradually loose top end power. No foul sounds from the engine at any rpm. The propeller is fine and I have found no water in the gearoil.

Grateful for any input.

Bjorn

 

[JUSTINTIME]

Re: 90 hp -1999 top end power decrease

how does the prop look?
when was the last time u cleaned the carbs

 

[BugEyes]

Re: 90 hp -1999 top end power decrease

how does the prop look?
when was the last time u cleaned the carbs

Thank's for the reply
The prop is fine and had no contact with anything but water last season.
I have not cleaned the carbs and I don't know if the previous owner ever did. Will try that for a start.