Couple of problems

So guys I have a few weird problems with my 81 750 Seca. Have a seat theres a few of them.

1. My auxillary/fog light isnt working. The lamp is relatively new, luvmy40 replaced it a few years ago, but it hasn't ever worked from what I remember.
2. My tachometerhas been flaky but a couple weeks ago it cut out completely. Every once and awhile in 5th gear its jump up to 1k then buries back below 0.
3a. My turn signals sometimes wont turn on at all.
3b. Even stranger lately using one signal will turn the other two on so it looks like I have hazard lights on.

Any help?

 

Get yourself a Workshop Manual.
Genuine Yamaha, ... Specific to your Bike.

Then, ... treat yourself to a good Test Light.

http://www.rjtool.com/circuit-sounder-p ... an-72.html

Afternoon Test Light Festival.
One step at a time.

 

My money says you have a short in your signaling systems wires caused by a pinched or stripped '+' wire. I'd start looking at where the wires in your turn signals enter the tubes and exit to the lights, look inside your headlight bucket and examine those wires there, and look over the wires going to luvmy40's work.

And yea what Rick said also-cause owning a classic older bike without a manual is like following hiking advice in the Grand Canyon from a Spanish speaking guide when you can't speak Spanish.

 

Search FAQ suggestions for bigfitz's write up on lubing the tach and speedo, it should resolve your jumpy tach issue.

 

A good idea might be to strip the bike down a bit and go through the wiring harness (looking for breaks, and unplug and plug back in connectors a few times). I just went through some weird corrosion issues in my wiring harness.

 

From what luvmy40 has told me it's an electric tach so I don't know if lubing it would work. However I will do this for the speedo since it cut out on me last night on the freeway.

 

Have you checked and cleaned the earth points? We're talking spotless metal to metal contact.

If you still have a fuse-box with the glass tube type fuses then they can throw up all sorts of weird and wonderful glitches.

 

+1 on the fuse box (all your problems sound like they are on the same circuit)
+1 on the factory manual + test light.

 

#2 Might be as simple as a loose cable.

This has actually happened to me twice over the years. Check to make sure both ends on the tach cable are securely tightened. My first jumping tach was the cable backing out of the head. Second was the back of the tachometer.

 

The 750 has an electronic tach..no cable.