So my tach died...

1981 XJ650 Maxim, mechanical tach.

Tach has started going wonky. At first, the tach wouldn't respond when the bike was first started, but give it a rev and it woul "catch" and read normally.

Then it stopped reading. I took the cable off the back and started the bike. The inner section spun as expected, varying with RPM. I connected it back but still no tach. I tried 2 or 3 times making sure the inner section was pushed into the gauge as much as possible, and finally it worked.

Lasted two days, now no tach. I tapped the tach a few times to see if it would work, and yay, I must have broken the light as I drove home with no tach and now no light on the gauge.

Time for a new tach? Any chance of fixing the existing one? Should I try a new cable just in case it helps (longer, maybe a more squared end, cheaper than replacing a tach from what I can see).

 

The mechanism can be cleaned and lubed, just be careful not to get any brake cleaner etc. on the face, it will destroy. PM me if you need parts, I have a ton of maxim gauge parts and have rebuilt a few. I also have a near NOS tach if you want it.

 

Thanks. Should I take it apart or just spray into the cable interface?

 

Take it apart. That unit is pretty simple to disassemble once removed. Once apart you'll see the input shaft with a magnet and magnetic cup that drives the needle in the back. These need to be cleaned and absolutely free spinning for the tach to work. I can get a pic later tonight if you like.

If the cable is spinning when unhooked, it's probably good but it won't hurt to pull the cable, clean, and lubricate it. This not only helps the cable "live" longer, but gives you a smoother tach.

 

I wish I could do that with some of my bikes, CB 900 sealed tach and a spider got inside and webbed the needle. After a few minutes of reving the bike it broke free but I still have a ball of web on the needle

 

Well you "can" open those but getting the ring back on factory like is tough. I did a Kaw one by carefully prying the back of the ring off, Once back together you wouldn't see it unless you looked for it.

There are some companies that will rebuild/repair if you want the correct look.

 

I have seen it done but I can live with it for now. Should be easy enough to get a good used one for that bike seeing more and more 900's coming up as " project" bikes.

 

Fitz' write up, no sense in reinventing the wheel:

http://www.xjbikes.com/forums/threads/speedo-and-tach-dissection-with-pics.15303/