slow, bouncing tach

[2618]

My tach on my 82 cbx tends to bounce between 43 and 5000 rpm when it is running in this neighborhood. It is smooth as slk below and above this range but it is slow to react when pushing over 5000. Any Ideas?

Thanks Dan

[alimey4u2]

Drive cable good ? Cable ends nice & square ? Tach making funny noises ? Drop of WD40 in the tach bearing normally extends their life a bit.
Failing that, the tach may have spent some of its life on it's face & some of the damping fluid may have migrated...

[spencer]

WD-40 is only a temporary lubricant. It evaporates.

[CBXRoger]

Al my tach issues have been related to the tach cable. Pull the cable from the sheath and give it a good lube job. If that doesn't fix it, check the end of the cable where it goes in the tach drive.

Roger

[SteveG]

Dan,

I had exactly the same issue with my '82.

Read this thread:

viewtopic.php?t=4301&highlight=

and see if this doesn't cure your woes also. Make it to the end of the thread. It kind of changed topics midstream (darn hijackers)

Let us know!

Steve

[Don]

Link doesn't work for me . . . . but if the rubber cushion his tach is mounted in is shot, it can cause the problem he's having

Don

[2618]

Thanks for the tips guys, I just put a new cushion in a few weeks ago with no improvement, but I'll check the cable closely and try lubing the tach bearing- just a shot of wd or Triflow??? in the bottom of the tach? I may drill test it but I drained the oil for the season. So I won't be able to engine test until spring (Wisconsin). The tach was also in the mount.

Thanks again
Dan

[daves79x]

Just turn the tach upside down and drop 2 or 3 drops of LIGHT machine oil (3 in 1 is good) down the drive hole. Let it sit upside down for a few minutes, then get it upright again. You don't want oil oozing out on the faceplate. That should cure your bounce. If not, it will have to come apart for cleaning. There are a couple of guys that do that work.

Dave

[80 cbx dude #6216]

Short of disassembling the tach and pulling the magnet apart from the frame external lubing doesn't really work.The drive hole where the cable goes is a blind hole not open to the inside of tach.Possible rebuild or replacement time.

[2618]

What can be rebuilt in one of these?Does anyone have instruction or pics of disassembly? Thanks Dan

[EMS]

The instruments are crimped by the metal ring around the glass. You can only open them by uncrimping the ring or cutting the plastic housing. Putting them together again is a little more difficult.

[CBXRoger]

The real solution to your problem is to always drive at speeds above and below the range of 4300 to 5000 RPM. ;>)

[Terry]

Say Roger, what's the top speed limit in Hawaii? And, do they still have an (Interstate) numbered highway over there?

[80 cbx dude #6216]

The speedo and tachs on most japanese motorcycles are stamped together-some what crude in design-pieces of ----.I used to work at a speedo shop in the 80's and rebulding jap speedos could be done but donor parts were required to repair them.Used or new would be best.
Mike

[Larry Zimmer]

Sorry to be slow getting to this. I know exactly what you're talking about. What I have found to help considerably is to be certain that there no binding in the outer cable housing. To do this be certain that the housing is free and not binding in any way when you tighten the ferrell nuts at the ends. Next, when you tighten the ferrells, hold the hex of the outer cable so that it DOES NOT MOVE/TURN as you tighten the ferrell nuts. While this did not completely eliminate the issue, it significantly improved things. Perhaps, even better care with alignment of the cable housing could do even better. New inner cables, etc. haven't seemed to do anything. Hope this helps some.