5hp Mercury

[N52129]

Problem:

2001 5 hp merc will drive sailboat 1/2 knot faster with cover removed.
Seems to be an air intake issue.
sugestions....

[GordMay]

Greetings and welcome aboard the CF, N52129.

Clean the air intake (filtre)?

[sandy daugherty]

Even after running for an hour, the little stream of water running out the back of the powerhead should still be just warm, not very hot. If its hot, the engine is running hot from a damaged impeller, plugged intakes (in front of the prop), or blocked passage to the exhaust arount the prop hub.
What boat and what speed?

[N52129]

Thanks guys
It's a Kirby 25. Normal high spped with the motor is 5.7 occasionally
hits a 5.8. With cover on max speed 5.2 on flat water, take the cover
off and 5.7 -5.8.
Impeller was replaced at the first of season and water temp seems to be cool enough during normal operation.

Not sure about the air filter. It appears to me that there is only a plastic cowling with a small hole in it at the centre over the front of the carb.
Am I missing something?

Any other suggestions?
Regards