I don't have a manual and was wondering what the proper RPM is for a 125HP Merc at idle in neutral ?

Also bought a volt meter that came w/out insructions and was hoping someone would know how to connect wires to it. One post has a [ I ]  one has [ B ] and then the ground post. Any help Guys ?

Thanks.

not really sure, but I was going to ask a similar question.

I am borrowing my brothers boat, and it runs a 125hp Merc

I will check out what RPM's it is running at idle this weekend.

The motor was just rebuilt last year.

My question is what is max RPM? Right now its turning 6000rpm at WOT with a 21 pitch prop, I think that is a little high. I think a 23 or even a 25 pitch might be the better prop. The boat has a wicked hole shot and tops out at 48-49 MPH.

The manual on my 60 hp specifies 750 rpm for all of the Johnson/Mercury engines, regardless of horsepower.  It's a 1990 manual, but it should give you a good starting point.

Also bought a volt meter that came w/out insructions and was hoping someone would know how to connect wires to it. One post has a [ I ]  one has [ B ] and then the ground post. Any help Guys ?

I = ignition (switched power source)

B = constant on connection to the battery

G = ground

Thank's for the answers . With my Procraft 175 with the 125 merc at WOT it will top out at 55-58. I have a 24 pitch Laser II and it runs around 5500 rpm;s. No GPS.