Motorcycle Repair: need real answer re: 1983 Yamaha 920 virago tachometer works intermittently, yamaha virago 920, electronic tach

Question
Expert: Collin Bradham
Date: 9/26/2006
Subject: 1983 Yamaha 920 virago tachometer works intermittently

Question
The tach on my 1983 Yamaha Virago 920 works sometimes but is not steady  or always correct, sometimes it does not work at all.  I checked all the connections at the tach and followed the wires to the point they go into the engine and found nothing wrong.  Should I get a replacement tack (used ones still available on internet) or is there a sending unit that may be the problem?  Any help appreciated as I am about to give up at this point.


Answer
There has 2 b some kind of "drive" for the guage.  It can't tell RPM by wires.  I would say that u have a bad tach cable, but it may b the tach itself.  Remove cable and make sure it turns freely.  If it does, then I would replace the tach and the cable as well.


My followup question sent on 10/1/06

"This bike has no cable for the tach just electric wires from the sensor to the electronic tach itself.  It is like the car tach you connect to a spark plug wire but it is permanently wired from engine sensor to tach with wires in a wiring harness.  I checked the wires and found nothing wrong.  I do not know how to test the sender unit or the tach itself.  Any advice?  Once again it is not cable driven!


Answer
Hi Chuck,

I think you're problem may be related to this:

http://home.earthlink.net/~ridevirago/tach.htm


Visit Virago Tech and review some of the tech files listed there. This is a very good Virago resource:

http://viragotech.com/phpBB/portal.php


Respectfully,
Mark Shively