johnson 125 rpms.....

[natedawg]

ok i got my boat out and ran it for a couple of hours it ran great would hope right out of the water and move speedo said it was at 35 to 36 mph. but i dont know if i can trust that its the old water pressure thing.. i think i was moving faster but oh well my question is at top end wot im only getting 4800 to 5000 rpms i see other post of similar motors with 5800 rpm is my prop wrong? or should i just not worry about this and be happy? every thing on this works great and im happy with it just want the motor to be happy. <br /><br /><br />thanks you guys are great keep it up....<br /><br />Nathan

 

[angus63]

Re: johnson 125 rpms.....

Is the motor cavitation plate even or higher than the bottom of the hull? Are you trimming properly? Is the timing correct and the throttle opening fully? I would investigate the above first before doing the prop swap. What year is the 125hp? Probably wanna see closer to 5800 than the present wot to keep your motor "happy".<br />Good luck

 

[natedawg]

Re: johnson 125 rpms.....

the motors cavataion is even with the bottom of the boat and i know the timing is right i messed with the trim and no help there guess i should see if the throttle is open all the way didnt check that yet.<br /> thanks

 

[ezeke]

Re: johnson 125 rpms.....

Sounds like your 1972 motor is happy. If the propeller is in very good shape you might improve by moving to stainless if it is aluminum, or moving to a higher pitch. I think I would stay put and replace the prop if it is worn.

 

[natedawg]

Re: johnson 125 rpms.....

nope the prop is in really good shape no nicks or anything just the normal paint wear on it. well i will check the throttle and see but i dont think i wat to mess with it too much. and whats the word on the speedo how accurite are the old water pressure ones? cuz like i said it seems to me that the boat was faster than the speedo says, or it could be that i just think it is.

 

[ezeke]

Re: johnson 125 rpms.....

Measured against radar or GPS, there is considerable variation because neither radar nor GPS can adjust for the current.<br /><br />Also, the variation is proportionately greater as you move slower. <br /><br />I put a new faria on last year and ran it against my Garmin GPS. At 40 GPS, the faria was 3 to 4 off one way or the other depending on the tide. The old OMC one I had was about the same, and neither one could give me a reading while trolling.<br /><br />The Garmin transponder that goes with my GPS has a wheel on it and that seems to be the most accurate of all for trolling purposes.