83 Tach Woes

If it's broken or just needs tweaked

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karben
Posts: 32
Joined: Wed Apr 08, 2015 9:25 pm
Location: NE Kansas

83 Tach Woes

Postby karben » Fri Jun 05, 2015 12:22 pm

So, last week my tach magically worked for two days straight. I loved being able to see my revs
It also helped me better judge what rpm I was at. It has since stopped working again (I bought the bike with it not working so nothing surprising). The gauge cluster I have is the rectangular one that I believe was only used on the 83-85 cb650s.

Firstly, where the hell does the cable run that goes into my engine to simply determine the rpms? I've gotten down on my hands and knees multiple times with a flashlight and I can't find any sort of cable that goes into my upper or lower blocks anywhere. Sure there's lines that run from the oil pump/cooler but other than those I can't find shite.

Secondly, I was looking at a wiring diagram on the bike and I'm really electrically challenged but I was able to decipher what color the wires are that not only control the bulbs behind the tach but apparently which wires run the electronics too. I couldn't find the wires for that either. Checked under the seat and behind the headlight and I should probably check again but I couldn't find the correctly colored wires at all.

Thirdly, if it makes a difference... My battery terminals seems to developer the white puffy corrosion pretty quickly. So last week I took some sand paper and sanded and cleaned the terminals and cable ends. After I did this is when the tach started working. Also, there's a 'pie' slice missing from the circular washer that gets bolted to the positive terminal. Like maybe a 1/6th of the circle is just gone. Charging system is good, etc but I am looking to replace that positive cable here soon.


Thanks guys!
1983 CB650SC Nighthawk

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: 83 Tach Woes

Postby cb650 » Fri Jun 05, 2015 12:44 pm

Your tack is electronic not cable driven. You must have a short in the wiring somewhere.
Did you clean the tank out?!?!?!?!

karben
Posts: 32
Joined: Wed Apr 08, 2015 9:25 pm
Location: NE Kansas

Re: 83 Tach Woes

Postby karben » Fri Jun 05, 2015 1:48 pm

Any idea where to start? Would the majority of the wiring be behind the headlight or under the seat? It must hook into a harness somewhere to get power. Would it be one of the bullet connectors or a part of a harness?
1983 CB650SC Nighthawk

cb650
Posts: 2959
Joined: Fri Mar 03, 2006 7:20 am
Location: Denver CO USA
Contact:

Re: 83 Tach Woes

Postby cb650 » Fri Jun 05, 2015 6:11 pm

no idea on your bike as its a DOHC.
Did you clean the tank out?!?!?!?!


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