Tachometer is way off (doubles rpm?)

[mrclubike]

I agree with George
More than likely it is a bad capacitor (condenser) inside the tach 
I don't think it is a ignition problem but anything is possible when it comes to electricity   

If you can solder they are easy  to replace and cheap 

[georgesgiralt]

Well, changing the bulbs in the speedo or tacho is not heart surgery. So i bet you can achieve it.
If I were you, I would buy little led bulbs with the T10 base like the original and install them for general lighting of the instruments. Since I've done that, I can SEE at what speed i'm running at night !
But put plain bulbs in the oil, gen neutral or high beam places or else wear sun glasses all the time, even at night ;-)
Look at the bike user manual, all the replacement of these bulbs is explained with pictures. Also, check the fuses. while you're at it.

[RG68RG]

Well, changing the bulbs in the speedo or tacho is not heart surgery. So i bet you can achieve it.
If I were you, I would buy little led bulbs with the T10 base like the original and install them for general lighting of the instruments. Since I've done that, I can SEE at what speed i'm running at night !
But put plain bulbs in the oil, gen neutral or high beam places or else wear sun glasses all the time, even at night ;-)
Look at the bike user manual, all the replacement of these bulbs is explained with pictures. Also, check the fuses. while you're at it.

The light for the speedo isn't just missing.. any wires or sockets are as well.. As for the tach? it appears that there are several screwed into the board inside and none work there either.. I'm searching for a fusebox on the bike now as it appears to be strangely hidden...As far as getting bulbs into the non working tach.. I could probably retro fit something in there but the tach still wouldn't work. The only thing it looks like I can practically do, is wire up a light into the speedo. (maybe off the headlight) Which I'm pretty sure is 10mph off. Maybe if I had spent more time with soldering guns and less time with wrenches these last 35 years... Just a thought....Has anyone on this board successfully added an aftermarket speedo/tach combo? Maybe digital??

[mrclubike]

Their are only 2 fuses
They should be in a fuse holder that clamps to the top tube at the rear of the fuel tank and directly over the air cleaner

The wires for the  marker lights and instrument lights are Grey/Black
The fuse you are looking for should have a Grey wire coming into it from the ignition switch and a grey/black wire coming out to the lights

Do you have a wiring schematic

[Bob_Roller]

We've had members install an Acewell unit, pretty straight forward to install and they seem to be satisfied with it .

[mrclubike]

Here is the inst lamp and marker circuit called out in RED

[Justin B.]

You can also install a Vapor computer if you don't mind homebrewing some mounts.  It's a digital speedo and tach combo.

[RG68RG]

Was just reading this topic again because I'm installing an electronic speedo/tach.. It's possibly junk but so far everything works except the tach. I've hooked the gauges tach input directly to the existing bikes tach wire with no luck. Wrapped it around the spark plug wire as directed by the instructions and ..no dice.. where else could someone attach one to get a signal?  It's an 83 and I'm not sure if it's electronic ignition yet as I haven't taken the cover off just yet. 

[Bob_Roller]

Starting with bikes produced 9/80 and later, they come from the factory with electronic ignition .