77D Tach repair?

[XS650D]

I noticed that my Tach needle goes wacko once up to 5000 rpm, it will fluctuate back and forth 1000 rpms.
I tried a new cable but no change.I ordered a used unit from Fleabay and its no better. Whats involved in
making the Tack work correctly. I tried removing the tack and inserting a cable with my drill and it seems to work correctly. Also turns smooth by hand.Im stumped on this one. Now I have 2 Tach,s and neither work rite! What am I missing.Worth noting the cable broke 2 seasons ago and replaced, been fine since other than the wacko needle!

 

[Raymond]

FWIW, similar problem. The two small screws that hold the dial fell out, so I pulled the tacho apart, refitted the screws, with a dollop of Locktite, put it back together. But now, don't know if it started immediately after the surgery or if it's related, the needle fluctuates fairly widely. Variable - sometimes fairly steady, but at what I imagine might be 4,000 often shows 3,500 - 4,500.

There's a thread - Mailman? - about pulling the instrument apart and re-assembling it.

I'll be interested to see what people have to say.

 

[jetmechmarty]

My tach was bouncing around at 5K and 60 mph. A few days ago, I lubed the cables with white lithium grease. It's still bouncy but about 3100 at 60 mph. Speedo isn't really reliable either.

 

[5twins]

You might try lubing the connection point where the cable attaches, maybe it will help. It will require the tach to be removed and sitting upside down so the oil can seep down into the joint. I have about a 6" length of old tach/speedo cable with the squared end that I cut off an old cable to use for testing.

I'm not sure you'd find anything amiss inside if you took one all apart. About all you could do to it is clean it all up and add a little grease to the spinning spindle bushings. That may or may not help. I recently renovated a couple for my '83. Both lagged between about 3500 and 4500. When the first one did it, I installed the 2nd, and it did the same thing, lol. So, I just left the 2nd one on there and in a few hundred miles, it seems to have corrected itself. Both of these tachs sat idle for many years so maybe they just needed some run time to get going correctly again. I may put the first one back on this year and see if it will fix itself in time too.

 

[member28833]

Besides cleanliness and lube, I try to "float" the securing finger nuts and cables to be as centered as possible when tightening. There is just a bit of looseness and if you are not paying attention the cable can be tightened in an "off center" position.
Think about what effect that would have spinning?

 

[Mailman]

There's a thread - Mailman? - about pulling the instrument apart and re-assembling it.

In the tech section 650Skull ( Doug ) has compiled just about every useful thread on the subject, it also includes a link there in , to my tachometer repair.

http://www.xs650.com/threads/70-83-...damper-replacement-replace-face-decals.52013/

 

[XS650D]

Thx guys. I just removed the gage from the mount and tested, no jumping tach. I tried one I have from a 1984 special and same result. I think the rubbers are all mushy soft and dried out. Can u get new rubber gaskets for these ?

 

[XS650D]

What I ment was I left the gage hooked up to the cable but not attached to bike in it’s mount

 

[jetmechmarty]

Can u get new rubber gaskets for these ?

Yes, from your favorite OEM part source. You may want to check Sumo Rubber.

 

[XS650D]

Thx will check them out