Tach no workee.

SO, my 82 XS400r has a non-working tach. It usually just sits at 0, some times will move around, seemingly at random. I pulled cable out of the gauges, and it doesn't turn at all with engine speed. I'm thinking I need to pull it out of the engine block and see what's going on there, but I'm not sure how to get it out.

Anyone able to shed any light on this?

 

Just above where the tach cable drive protrudes from the head, on the top of its cast tunnel, is a small bolt with a washer. That bolt retains the tach drive gear bushing in the head. Remove that bolt, and the tach gear housing/bushing can be pulled out of the head along with the gear. There is an oil seal (Yamaha pn 93101-08132-00 OIL SEAL, S-TYPE) on the housing.

More likely you have a cable problem though.

 

So the cable is all chewed up on the engine side, so i'll be buying a new one. One thing that I noticed - I cleaned the faces of the gauges while I had the cluster apart. Th speedo needle was easy to move out of the way to clean under. The tach needle was quite hard to move. Is that normal?

 

Nope.

Instrument service: http://xjbikes.com/Forums/viewtopic/t=15303.html

The "reluctant" tach may have contributed to the demise of the cable.