Tach acting funny

[stevestrom]

Alright, I am going to start a new thread since I am not getting any responses in my other thread.

I have a question about the tach. I have everything hooked up and the tach works at an idle but when I rev the engine it won't go passed 2000rpm. The engine itself revs past 2000rpm but the tach won't. Is my tach screwed?

It's an XJ1100 but the tach is from an XS1100

[bikerphil]

It probably needs taking apart and lubing if all the electrical connections are good and free of corrosion. There might be a way for lubrication with only partial disassembly, someone who has done it will hopefully chime in.

[DGXSER]

not sure. I know that it is common for it to bounce around and be very eratic with dirty connections. Could be the issue, it can't hurt to check all the associated connections.

[stevestrom]

All the conections are good, I just replaced them all. I didn't open up the tach unit though. Maybe I'll hook up the old XJ guages and see if they work, Could they be incompatable?

I was sure that it would work and it does while under 2000 RPM (idle, with minor reving the needle does not bounce).

I bought the guage off ebay was sold as working and it appears to be in really good shape.

[Southhill101]

My xs1100 tach had worked a small counterweight a little loose on the mechanism inside the tach, allowing it to rub inside and stick at 2K rpm, as well as the same position on the other side of the dial. I located it quite quickly after opening the tach, which is detailed elsewhere on this site. Sometimes it would just stay there for a bit when the rpms had gone back down. It's just a friction fit metal disk on the end of a plastic arm. Pushed it back into it's slot all the way and it hasn't been an issue since.

[CatatonicBug]

I'm just throwing this out there, but the XJ has a different alternator than the XS. Since the Tach runs off the alternator signal, it seems to me that an XS tach would not work on an XJ. Anyone have experience to the contrary?

[natemoen]

The alts act the same and the signal outputs are the same it is just how the alt does it that is sifferent. Just like how the alternator that tc is using still works the tach the same. Tc's alt is functionally the same as the XJ alt.