tach is reading high at start-up

[Dub3]

Hi guys,

My tach reads high on initial start-up. At idle it will register as high as 3-4,000 rpm then after awhile it will settle down and read close to actual rpm.

Today it read 5,500 rpm for 10 minutes or more. I know from the sound of the motor and the speed I was traveling the motor couldn't have been reving over 3,000 rpm later it settled down to a more correct reading. After shutting down and restarting it seamed to work OK.

I have cleaned the contacts on the back of the tach to no avail.

What is the problem? Thanks in advance

[Troy250]

When mine did that it was the rectifier going bad. I replaced the tach and that did not fix it. Replaced the rectifier and was good to go.

[ChampioNman]

If you have wing nuts on your cranking battery posts get rid of them and replace them with either stainless steel hex nuts and lock washers or stainless steel nylon insert hex nuts. Make sure your ground connection on the motor is clean and tight also.