erratic tachometer

[lvrsnr]

my tach is erratic (motor speed changes but tach reading does not) from 2500 RPM to about 5000RPM.. if memory serves me much of the tach problems we had 28 years ago where really bad voltage regulator/recitifiers.. if anyone has more current experience I wouldn't mind hearing it. thanks oh ya my bike is a XS1100LG.

[blue giant]

Hi lvrsnr, here is a link that might be of some help

Tach Issues

Cheers,

Paul

[bikerphil]

tach

First, clean the connector coming from the alternator. Remove the fuse block mounting panel and it's behind there. If problem still persists, clean tach harness connectors inside the headlight bucket. Last resort, take the tach apart and clean corrosion from pc board and re-heat solder connections of wires leading toward headlight bucket. Should be ok if all these connections are clean.

[scott0757]

Tach diagnosis

Have this problem as well and checked all the line voltages notes on this and other posts. All tested well and the tach works great when removed from the bucket, but the minute I slide it into position, the needle goes crazy again!

I checked for shorts, pinched wires and possible grounding of the tach shell to the bucket and can find nothing. Added rubber bands about the shell body as added insurance against bucket shorts and looked at the mounting insulators as well and all appear to be fine.

Any ideas? If the tach shell comes in contact with the bucket (meaning the rubber gasket and washer seats are electrical and not just vibration insualtors), should that have an impact?

Would love an opinion

[backroadspecial]

Scott0757,
I have the same problem concerning the tach. It works fine out of the cup, but when I slide it into place the needle becomes erratic again. I have checked grounds & soldered in an add'l ground wire, but that did not change anything. I am thinking that some wires get crunched when slid into position, but cannot see anything visually. Did you get a fix for this as nothing more is posted. Thanks

[Radioguylogs]

Me too

BikerPhil has the right procedure to find the problem.

I just had a similar problem- Tach was erratic and jumpy above 4k RPM.

I double checked the connector behind the fuse panel and the headlight bucket connectors . No problems.

I replaced the Tach itself and the problem was cured.

Maybe the mounting bolts can distort the Tach in a way to cause a problem to manifest itself. Other posts have explained that the electric current has to pass through delicate bearings inside the Tach.