Question about prop

[rme hunter]

I think the prop is the problem as well. When I bought the boat it had a 24 pitch on it. I down sized to the 22 that I have now and I am about to go down again. Could the plugs have anything to do with it? The motor isn't missing but I am just not a mechanic.

[ttwigg]

I had the same boat, Mine had a 115 johnson and I got 58.8mph on a gps. You need to try several props. You have a great boat, I wish I still had mine at times. On the speed thing, you might have too much junk in your boat. I took 60% of the crap out of my new boat and the performance was much better. Good luck........

[rme hunter]

Do you remeber what prop you had on yours?

[DaveR]

what RPM's are you getting now at wide open throttle? Got to thinking, engine height could affect speed, but not by 10 mph. A jackplate is an investment, but would allow you to tweak the rig with the right prop and improve driveability and will typically get you 1-2 mph increase.
The plugs shouldn't be affecting the speed unless they aren't firing and you aren't running on all cylinders. call the Ranger factory and get ahold of the rigging department, they can tell you what prop they rigged that model boat with for a 125hp typically and that is a great place to start. Until you get close to the right prop, hard to tell if engine is running right. Good Luck.