Drunk tach needle

I rarely ride the bike for more than 40-50 miles at a shot - mostly to and from work - but there have been a few occasions where I've had to drive to Milwaukee and back over the course of a day (180 miles, thereabouts), and this weekend I put about 180 miles on the bike cruising through Central WI with my brother-in-law.

So here's my question - toward the end of these long drives, I notice that the tach needle has a tendency to act "drunk" - that is, it registers about the right value, but it will "drift" and bounce around the value. It's not speed-related, as I'll be driving the same speeds early in the trip, and the needle is dead accurate, and today (two days later), it's registering just right again.

Has anyone else seen this, and do we have any theories as to why it happens?

 

It probably just needs to be cleaned and lubed. Easy on our bikes.

550 Seca cluster teardown: http://xjbikes.com/Forums/viewtopic/t=14948.html

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

You also may need to lube your tach cable. It may be "gumming up" once it gets hot; pull it, flush it out real good and lube with something heat-resistant like Tri-Flow or good ol' motor oil.

I put 174 miles on my '83 on Saturday, its "shakedown run."

 

The tach gets its signal from the coils.

 

Not on the 550s - tach is mechanical, cable feeds into the front of the engine, above the headers.

 

Mine was doing the same thing. Not long after it started leaking oil and I had to change the o-ring and seal in the tach drive unit thingy. It's been good ever since.

 

I have two Seca 650's, the first XJ650RJ, Silver blue model was a mechanical tach and the second is the XJ650RJC, Red white model has an electronic tach.

My mechanical tach was acting drunk as well, but was unable to get the tach open to clean and lube.

Ken

 

I keep forgetting to check the O-ring, so that could be part of it. I should just order one and get it taken care of, so I can stop worrying about it...

 

I think Fitz is right. I would go through the tach and the speedo. Give them a good clean and lube job. You might want to think about LED bulbs when you got them apart. I'm going to do the same job to mine next rainy day and post some pictures if I can figure out how photo bucket works.


MN

 

I had the tach apart and cleaned it about a month ago, so I'm going to go with cable on here. I'll try cleaning and re-lubing the cable as soon as I figure out the noise issue from my other thread.

Fitz, one question - when I had my cluster apart, I could NOT for the life of me figure out how to get the speedo out of its bucket without breaking the trip. Is there a trick to it?

 

mine is electrionic on the XJ750RJ, the dash cluster is almost new (boxed up and put away in 82 with only 1211 miles, as was the engine, just put both on the restore 5 months ago) above 6k my needle starts to bounce + or - 500 to 1000 RPM's any idea what is going on here and how to fix it?

 

not so much a bounce, more like it's waving at me

 

Yep.

The trip odo reset knob is reverse-threaded; it will (should) unscrew off its shaft. If it got tightened up so tight so it won't come loose from the normal resistance provided by the trip odo you may have to sneak a pair of small long skinny needlenose pliers in there and grab hold of the metal part of the shaft. I've torn down probably half a dozen clusters and have had to do that once or twice.

If you get it unscrewed and the (plastic) threads stay behind (as in overtightened now it's stripped) let me know; I can send you one.

 

Sounds good. Exhaust gaskets and cam chain today, speedo clean and tach cable lube this weekend. Thanks!

 

Aaaaaaaaaaaaaaaaaaaaaaaargh. Now my tach is behaving (like it usually does), but my speedo is stoned!

Instead of being nice and responsive, it's dull and sluggish; it'll eventually get to the speed I'm actually traveling at, but it takes some time.

So, full cluster and cable teardown, cleanup, and relube. Fitz, I have your excellent tutorial available for the actual cluster work; my questions concern the cable lube.

Reading in the Clymer guide, it sounds like the tach and speedo cables, unlike the control cables, can be pulled right out of their plastic housing. Okay; so I pull these cables out and wipe the old grease off. Do I need to use some kind degreaser, or is a clean cloth going to be good enough?

Also, do I need to somehow clean out the sleeves as well, or am I okay just clearing the cables themselves?

Finally, what kind of grease should I be using on the cables? I've got a tube of the white lithium, or is there something better I need?

 

Tach and speedo cables: Yes it's a GOOD idea to "separate" them for cleaning and lubrication.

I lay a double layer of paper towels out on the floor long enough for the cable; then pull the inner out and lay it on the towels. (Keeps it from picking up floor grit.) Clean the inner cable, (I use brake cleaner aerosol) and then flush out the sheath. Put toweling over the end and blow it out with compressed air if you have it; or just flush it real good and be sure it has time to dry thoroughly.

Relubricate: If the lube is too thin, it will give up too soon. If it's too thick, it will attenuate the cable, especially in the cold.

What I do it to first spray the now clean and dry inner cable with Tri-Flow and give it a chance to soak in. Then I add 4-5 drops of good ol' motor oil to the sheath and put the cable in about 1/3 of the way, add a couple more drops of oil, push the cable in further; and use a small dollop of grease on the little stop bushing. Spin the inner cable with your fingers and work it in and out a bit to be sure the oil is distributed.

A word about that white lithium grease: It's only good for control lever pivots and stuff; it's NOT the least bit heat-resistant nor very "heavy duty." Don't use it anywhere things get real hot (like the bottom of the tach cable.)

And don't lubricate anything with WD40.

 

I would recommend a) getting a teflon sheeth for inside the cable and b) using liquid graphite lubricant on the cables themselves.

A regular bicycle shop may well carry the teflon. It is often used on bicycle cables. Then fill it with liquid graphite (with the cable in) and you should be good for a very long time.