Topic: Turn signals not working on 1972 CB750, 1034 vs 1073 bulbs. 1073 on front?

[VTCBike750]

So heres my question.  Hooked up the front turn signals I got off of ebay and they dont blink. My first thought was the relay.  When I got the bike in Nov the bike had Suzuki front turn signals and they worked just fine.

So far Ive found a few postings mention the problem when replacing the stock 1034/1073 bulbs with higher wattage 1157/1156 auto replacements.

I've also found that 1034 are dual element bulbs for the front signals and 1073 are single element bulbs for the rear signals. 

All 4 of my turn signals are 1073.  Does this make sense for this bike?

Id be a little surprised if the relay went bad over one winter sitting in a garage?

Any ideas?

[TwoTired]

I think front run lights didn't happen until 73-ish.  Which means the single element 1073 bulbs for the front are correct.

You could look into the socket for the bulb. One contact 1073, two contact would mean 1034 are correct.

Do the lights not illuminate or just not blink?

[VTCBike750]

Front lights illuminated all the time.  Rear light up when using the controls. I have the older mechanical relay and they don't blink while running the bike.

I found this:
http://www.sohc4.net/index.php/archives/85

Would the 1073 bulbs affect the blinkability?

[TwoTired]

Looks like you need to have the two element 1034s in the front and single element 1073 in the rear.

Look into the socket.  The contact nub on the 1073 *can* bridge both the contacts in a 1034 socket.  Could actually sort of work depending on the switch gear function.

[VTCBike750]

Hmmm, only problem is the 1034 cant fit into the 1073 sockets because of the tabs on the side of the bulb

Ive asked the Ebay sellers, and so far the front turn signals being sold only have 1073 bulbs.

[TwoTired]

Dual element bulbs have staggered nubs, so that the correct element gets powered in the socket.

But wait.  Are you now saying you yourself installed rear turn signal units on the front and are now confused about the bulbs they take?

These are the things POs do to these bikes!  I don't think I can help solve the problem, as I can't see the mods you've made.

The 1034s (with their proper sockets) need two wires and three connections to function as intended.
The 1073s (with their proper sockets) need one wire and two electrical connections to function as intended.

What wire colors did you use to power the front signals?

I don't have a K2 specific wire diagram in the HMM.  Perhaps someone with more model year familiarity can help you solve the issues.

Would the 1073 bulbs affect the blinkability?

Yes.  The 1034 blink section uses more wattage than the 1073 element.  The stock flasher is load matched to the bulbs used.

Good luck!

[jvandyke]

Wouldn't an electronic flasher solve this?  I put in a Tridon LF12 yesterday ($6 at car parts place) and have nice consistent speed flashing.  Fit in stock location too.

[VTCBike750]

But wait.  Are you now saying you yourself installed rear turn signal units on the front and are now confused about the bulbs they take?

Nope the front signals Im using I bought off ebay, sold as front signals. They have 1 wire and fit 1073 bulbs. I also looked into it and the ones the PO put on had one wire, therefore 1073 bulbs.  I havent really made any mods to the bike, trying to get it back to as near stock as I can.

Part of the confusion came from the fact that http://www.sohc4.net/index.php/archives/85 state that K2s use the 1034 and 1073 bulbs, where as my wiring diagram  for the K2 shows 1 wire and a ground for all signals, 1073 bulbs. 

I think the problem with the blinkability is a grounding issue. The more Ive looked into it, it seems that a grounding issue can prevent flashing.  I bought new signal lamp stays from cb750supply.com for the front signals and Im wondering about the continuity of these parts.  I havent checked them yet, but I may have to run a ground wire from the signal's housing to the ground wire.  Everything has been wired up the way it was before and the way the diagram shows.  Only thing thats really different are the signal stays. Thats the best I can come up with.

Thanks for all the help.

[TwoTired]

Okay in the headlight bucket you should find light blue and Orange wires.  These are front turn signals.  If you also have run lights you will also find Orange/wht and Lt Blue/wht.  These would be for front running lights.

You should also find that the signal stalks must have an electrical connection to the green wires in the main harness.
Often there is a tab for the nut that mounts the headlight which has a green wire soldered to it.  This makes that headlight "mount ear" electrically connected to the green wires in the main harness, and provides a solid return path for the turn signal bulb filament.  There is no other reliable connection between frame headstock and fork components.

Maybe this will help?

[VTCBike750]

No running lights, just the light blue and orange wires.

Yup I have them grounded from the tab on the nut in the headlight bucket to the green wire in the wire harness.  I havent had a chance to get in there and look. Id be surprised if there is a grounding issue, but thats all I can think of at this point.

[VTCBike750]

Yup, had a chance to look things over. Definitely hooked up the signal wires to the solid black wires. I'll just make this easy and call myself an idiot