95 175HP evinrude vibration

[angus63]

Motor mounted on 21' trophy. From 1000 rpm to 1300 rpm, the boat vibrates in a rythmic pulse. Motor works fine otherwise at all other speeds. The prop is true. The motor doesn't seem to be missing. Is there a cure for a harmonic iteraction at a certain rpm? Presently I just try to avoid that speed but trolling becomes an issue.

 

[Bear]

Re: 95 175HP evinrude vibration

What happends if you tilt up just a little? That works for me from idle and up to 1500 rpm then it's gone.<br /><br />/Bear

 

[seahorse5]

Re: 95 175HP evinrude vibration

The relationship between throttle opening and spark advance is very critical, especially at those rpms which are the transition phase between the low to mid-range carb circuits. Mechanics call the adjustments "synch and link". It is explained in detail in the factory manual or can be done in minutes by a competent tech.

 

[angus63]

Re: 95 175HP evinrude vibration

Thanks Guys<br />Occurs at all tilt levels. I have the manual and will check carb sync.