We have a 2005 Johnson 25 long shaft. Ever since the motor was new it has been sloooow. It pushes our plain lund 16 ft to 20.5 mph with one 230 lb guy and gear. The previous motor a 80 's merc 25 pushed it to about 27 Mph via gps. My buddy has the same boat only a low transom and his freeken Tahatso 18hp pushes it to about 22 with both of us in the boat.

Boat planes fine and motor sounds great, no bog just seems like it is not hitting full RPM, butterfly and throttle stop appear to be open all the way.

Talked to the dealer last year about this and they said its just the way the motor runs...

Any info on how to speed this thing up would be greatly appreciated. It is now out of warrenty and time to tinker.

Thanks in advance.

J

Do you think the prop is correct for your boat and weight?

What prop do you have along with pitch and dia.
We run 16'ers with 25 hp on the Moose Chain and Sag. I'm only getting 20 MPH with no load and have to watch the RMPs. I'm proped for big loads and can plane out with 2 guys and a HUGE amount of gear.

You say you can plane out on problem, are you pushing the bow into the water? What position do you have the motors tilt at.
If your all the way down you'll need to lift it up. Go one position at a time. After that and your still not getting the RPMs up I'd start thinking about the prop. Coming down in pitch would be the logical choice but depending on what you have, having the prop cupped might be the best thing to do.
Call Jay Soderbloom and he'll have some suggestions. I had 15'er with a 25 hp that wouldn't get the RPM's up, poor hole shot and slow at WOT. Had Jay cup the prop. Top end is high 20's with good hole shot. 2 guys with Huge load and it'll plane out. With the cupped prop you would swear the prop is shifting gears as it climbs up on speed.

Thanks for the suggestions. I will have to look at the prop and get the pitch. It would have been what ever was sold with the motor, we replaced it once due to a rock issue on Big Trout. It was slow prior to this. It was replaced with what the Cabelas Catalog showed for it.

As far as the bow pushing in, that does not seem to be the case, as with one guy, the front will pop up good and you need to put a rock up there to keep it down. I have experimented with different setting on the pin to see if it makes any diff and it does not significantly.

I will look into the prop and get back to you guys. Thanks again.
J