83 seca 750 tach adjustment??

Hey all!
My tach has seemed to throw a fit with me. Maybe it doesn’t like it when I stretch the the bikes legs every once in a while. Anyways, I was on my way down to visit my girlfriend (40min ride one way) everything worked just as it should. I get to one of the stop lights in town and see my tach is “idling” at 2k rpm. So I go to adjust the idle at the light and it doesn’t move down. So I finally get to her house and play with the idle screw more and it’s turned so low it won’t idle so I adjust it back to where it should b, but my tach won’t go below 2k when running. Here’s a pic when the bike isn’t running and the ignition is on. Any help would be great!

 

Very common to have electric tach go funny. Many times it’s dust or spider webs etc. Pull it apart and clean the unit.

 

Most likely it is dirty. My father dropped a big box on it in the garage and broke the whole dash and left quite a dent in the tank. He bought a used one off of eBay from Florida. Will try cleaning tonight

 

Be very careful whem you dissasemble the ATARI. The glass isn't tempered, and isn't safety glass. If you break it, it will turn into shards.

This is a short overview f disassembly. You won't need to remove the glass from the bezel in order to clean the gauges. That step is reserved for when the bezel needs to be repainted.
Atari disassemble

 

Does it go to zero when the key is off?

 

Yeah it goes right to zero

 

I would suspect that would eliminate an issue with the actual meter movement as far as dust, etc. It would seem more like an actual failure on the attached circuit card that drives the meter. If you happen to have a variable power supply you can test the meter by disconnecting the two wires that attach to the CCA, and drive the tach with the variable power supply - the scaling is approximately 210 mv per 1000 rpm.

It gets more complicated (test equipment) to test off the bike, but you can connect the +12V and ground pretty easily while it is out and see if it goes to 2K without an input. If it does, then you could swap in the damaged unit circuit card and see if it solves the problem.

 

I don’t have that kind of test equipment with me. But I’ll see if I can borrow something of the sorts

 

Or just connect it to 12V, which is pretty easy to do and see if it reads 2K. That should be a good enough test to isolate the problem.