Tach acting funny, any ideas?

[81xsproject]

I have just began running my bike after putting it back together from the restore and the tack is acting screwy. It sits off at just over 2k and when it is running it goes from there to about five, but acts like it doesn't want to go farther. I haven't checked the connectors yet, but anybody have any other idea what it could be?
JC

[Ken Talbot]

As the tach is electrical, connectors would be a good place to start. I fought for quite a while with similar electrical gremlins on SWMBO's 'H a couple of years ago and that's what it turned out to be - one particularly bad connector within a block of 5.

[randy]

JC,

Is your charging system working OK? The tach takes it's signal from the alternator, so if your regulator is not energizing the field coil to it's full voltage, the tach signal voltage will be corresponingly low. ? My $.02

[81xsproject]

Randy,
how can I test this?
JC

[scoobes]

i had this problem a while a go,i just got another regulater from another xs1100 tried it on my bike,the fev counter worked perfect from then on,it is better if you know someone with a xs1100you could borrow the reg unit off.

[randy]

No need to swap regulators. Put a voltmater on the battery terminals and run the engine. You should see somewhere around 14.5v at 5000 RPMs.

[skids]

Randy, I think that method would tell you if you had a charging problem, but it wouldn't necessarily point to a bad regulator (I think), as something alse could be wrong if volts were down...However, I agree, it is the best way to see if something is wrong with the charging system in general.

Originally posted by randy
No need to swap regulators. Put a voltmater on the battery terminals and run the engine. You should see somewhere around 14.5v at 5000 RPMs.

[81xsproject]

If this is the prob, why would it not go down to zero when the bike is turned off?
JC

[randy]

Well, JC, if the meter reads zero at the battery, then the battery is dead! The job of the regulator is to supply higher than 12v to the battery while running in order to maintain a charge in the battery and run all of the electrical loads. That voltage rises as the alternator (attached to the crankshaft) spins faster with the rising RPM's. The voltage output of the regulator is supposed to top out at 14.5 volts at 5000 RPM.

Since the tach gets its signal from the alternator, I suggested that you test the running voltage to see if that system is working. If it is, we can move on to other areas to troubleshoot.

[81xsproject]

Sorry to be such a dunce, so, if the key is off, the tach is still getting a signal and that is why it stays at 2k?

[DiverRay]

If the tach is at 2K all the time, the inside is probably dirty. There is a thread on taking apart and cleaning the tach or speedo. That should solve your problem.
my $0.02

[randy]

WOW. Did I go off on a tangent there, or what? I thought you meant the battery went to zero, oh never mind.

What Ray said, yeah, dirty.

One more beer and I'll be normal again.