YAMAHA 60 Power (HELP!)

[Paul_Dublin]

I have a 5.7meter (19ft) Rib with a pair of 1995 3CYL Yamaha 60’s. Originally had 15” Pitch props and the right motor could reach 5700 Full throttle where the left would only reach 5400. They seemed to run at about 5300 with no problems at about 90% throttle although the left motor seemed to bog down when I opened them up to full throttle.<br /><br />I left them in for a service where the carbs were completely cleaned out. When I used them again they were running smoother but when I opened the throttle to 100% they would seem to bog down for a few seconds and then surge again (the right motor only slightly, but the left motor was worse). <br /><br />To reduce the revs a bit, I changed to a pair of used Aluminium 17” Props. It was with these that I noticed that the left motor was down on power compared to the right one. It would only rev to about 5100max where the right one would easily get to 5500 at about 90% throttle. It was very noticeable when the motors were used one at a time. I could easily plane on one motor, but the other was more difficult. When I opened the the throttle to 100% it would kill the revs to about 4000 and would rise up when I dropped it back to 90%.<br />One other thing I noticed was the new white props were pretty ‘smokey’ around the exhaust hub after the first day of use. Not sure if this is normal and I just didn’t notice before on already dirty props.<br /><br />A friend into Motorcycles checked the compression and said the bottom cyl on the left motor is slightly lower than the other two (about 10% less) and noticed that the Head gasket looked like it was replaced sometime in the past.<br /><br />I live in Dublin, Ireland and my problem is the Servicing and the Props cost me the equivalent US$900 plus a day off work …( Not blood cheap).. So I’d like an idea of what the problem is before I look into getting the problems fixed.<br /><br />Finally, I was out last night for a run. Did about 55km (35 miles) on 13 gallon (6.5 per motor) at about 4700RPM. Only 2 of us in the boat and the Sea was like glass.<br />Seems like a lot to me (Especially when fuel is nearly $5/gallon in Ireland).. Does this sound excessive?<br /><br />Sorry for the long list of questions guys, but this is my first “real” boat and I broke the bank buying it. Thanks in advance for the assistance. A creamy pint of Guinness is in the mail! <br /><br />Cheers<br />Paul

 

[jim dozier]

Re: YAMAHA 60 Power (HELP!)

Have someone go to the back and pump the fuel bulbs on the engines (one at a time) and see if it helps. You may have a failing fuel pump. Pull the plugs and check the color and condition of the plugs for a lean or rich cylinder.