********1986 Yamaha 90******************<br />About a month ago I had this same problem. I replaced a corroded main ground wire and it fixed the problem...or so I thought. On my last trip out<br />engine was running fine until about an hour into the trip. Engine would shake violently, above 2000 rpm and tach stopped working. Below 2000 and it would run fine. <br /><br /> I got home and tried a few things(changed CDI unit,checked ground wires etc.) I also changed the wire harness assembly on the motor(although it was an older one from a spare motor)and still have the problems. Can someone please shed some light? <br /><br />Thank you
