Low rpm

[Scott Danforth]

Motor is short shaft not mother, yes cavitation plate is bottom and center
How can I find out the gear configuration? Model # 0T518996 for the 40 hp mercury max rpm 5500 and 0t935153, 25 hp 6000 max rpm

Yet you stated both motors were long shafts

 

[jlh3rd]

doesn't matter what your hoping for.
Your motor, which you now say is running properly and at the right height, is telling you that with that 17" prop....your rpm is too low.....
there's no magic wand...

 

[Beamer50]

Too much pitch doesn’t cause cavitation on holeshot, just causes slow acceleration.

Well , it did on my Baja when I switched to the 21 pitch it would over Rev at hole shot , had to back off a bit until I got some speed

 

[Scott06]

Well , it did on my Baja when I switched to the 21 pitch it would over Rev at hole shot , had to back off a bit until I got some speed

Apples and oranges … were 19 and 21 same prop, was hub slipping? blade area, diameter, and cup all affect this.

Props are very application specific.

based on info given, assuming tach is accurate if you still have the 13” pitch try it

 

[Scott06]

Motor is short shaft not mother, yes cavitation plate is bottom and center
How can I find out the gear configuration? Model # 0T518996 for the 40 hp mercury max rpm 5500 and 0t935153, 25 hp 6000 max rpm

Good i was hoping we could leave your mother out of it… i put these serial numbers in on the parts look up at marineengine.com

40 hp comes up as a 2.00:1, 25 hp is a 2.25:1.so 40 hp has less gear reduction.

 

[Beamer50]

Thanks , can I change the gear configuration

 

[Beamer50]

Not sure why you're hung up on using the 17" prop. If its truly running 3900 you're lugging the motor...big time.

For giggles, I ran your combo through Merc's prop selector and took an educated guess on a couple of items. Everything is coming back at starting at a 13" prop.

From what I'm finding on the Tracker V14, 20-25HP is max for that boat. Did you check your capacity tag?

Ok thanks

 

[Beamer50]

I had this rpm gauge installed a couple months ago by boat mechanic, it's the same one that came with the motor. How should the tach be set , pulse etc.

 

[Beamer50]

Ok thanks

40 hp max motor 850 lbs max weight

 

[Beamer50]

Ok thanks

I just run it through marine engine. Com and it lists 9 thru 17 pitch . I'm not set on a 17 . I just want the best performance, top end speed if needed, cruise speed for less fuel consumption

 

[jimmbo]

I just run it through marine engine. Com and it lists 9 thru 17 pitch . I'm not set on a 17 . I just want the best performance, top end speed if needed, cruise speed for less fuel consumption

Prop it so it is runs in the Upper 1/2 of the WOT Range, preferably close to the top.

 

[fatlenny]

Dont over complicate things. I suggest google search "how to choose the right prop for your boat", there are many pages of information all saying pretty much the same thing. You have to play with different props to find what works with your set up. each 2" of pitch will change 200-400 RPMs. It is not an exact science as every application and prop manufacture will differ, but the 200-400 per 2" of pitch will give you a start. Sounds like the 13 pitch is the way to start since it sounds like you may still have it. if not, some places will let you try a prop before committing to it. If you blow out the 13 on acceleration, you may have your setup to high.

 

[Beamer50]

Prop it so it is runs in the Upper 1/2 of the WOT Range, preferably close to the top.

Thanks

 

[Beamer50]

Dont over complicate things. I suggest google search "how to choose the right prop for your boat", there are many pages of information all saying pretty much the same thing. You have to play with different props to find what works with your set up. each 2" of pitch will change 200-400 RPMs. It is not an exact science as every application and prop manufacture will differ, but the 200-400 per 2" of pitch will give you a start. Sounds like the 13 pitch is the way to start since it sounds like you may still have it. if not, some places will let you try a prop before committing to it. If you blow out the 13 on acceleration, you may have your setup to high.

Thanks

 

[harmanoff]

I had the same sort of thing you did, I had a 1986 50hp yamaha it died, found a sweet deal on a 2002 mercury 60hp came off a barge of a pontoon, with a 13" prop, dropped that like a hot potatoe, spoke to the mercury dealer he said try a 15 at first see where the WOT RPM's are at, it would go over the 5500 max at WOT so went to a 17, now at WOT max RPM ill get is 5400 id say perfect and it runs well, gotta go with what the others are saying try the 13 see what the RPM's are, adjust from there.

 

[racerone]

Changing the gear sets would be expensive if it could be done !!