Blinker Question

lazyeye6 · Jan 1, 2023

I recently acquired a'74 Interstate with 13,000 miles and which had been in storage for 20 years. The engine had allegedly last been fired up 2 years ago.
Beneath copious layers of caked oil and dirt is an amazingly original motorcycle. I installed a new battery and began checking out electrical operations and
found only 2 problems: Horn isn't working. I'm not worried about resolving that; Right side blinkers work normally. Left side blinkers blink very slowly.
With headlight on right side blinkers still operate normally, but left side blinkers both light up bright but do not blink at all. This is all without the engine
running.
Aside from digging into the blinkers handlebar switch for a poor contact, what else might be a cause?

Tornado · Jan 1, 2023

Think you have it with poor switch contacts. If the flasher unit was bad, should effect either side equally. Same with a poor battery or battery connections, earth connections.

Its good to clean up the earthing connections (z-plate, engine head steady, frame points etc) , even bypassing with direct to batt positive (at least for testing) as these can be a source of vexations.

When I first got my '74, it also had issues with indicators and horn, in hindsight was a poor battery and not helped by flakey ign switch further conflating testing.

marshg246 · Jan 5, 2023

lazyeye6 said:
I recently acquired a'74 Interstate with 13,000 miles and which had been in storage for 20 years. The engine had allegedly last been fired up 2 years ago.
Beneath copious layers of caked oil and dirt is an amazingly original motorcycle. I installed a new battery and began checking out electrical operations and
found only 2 problems: Horn isn't working. I'm not worried about resolving that; Right side blinkers work normally. Left side blinkers blink very slowly.
With headlight on right side blinkers still operate normally, but left side blinkers both light up bright but do not blink at all. This is all without the engine
running.
Aside from digging into the blinkers handlebar switch for a poor contact, what else might be a cause?

Since the right side works normally, most of the wiring is fine and the flasher is as well. Wrong bulbs, bad connections in the front or rear Green/Red wires, or bad bulb socket connection front or rear, bad handlebar connection, or turn signal grounds..

Disconnect the Green/Red wire and the Light Green/Brown wires that come from the handlebar. Jumper the connectors where you disconnected the wires. If the signals work correctly, the handlebar control is the problem; otherwise, it's the Green/Red wire connections/bulbs/sockets/grounds.

kommando · Jan 6, 2023

The OEM flasher unit is amps sensitive, bad connections reduce the amp flow and the unit slows the flash rate. I use the more modern voltage sensitive units which are less prone to bad connections and low alternator output at tickover. I also run dedicated earth wires which the standard light units lack as they use the chrome on the plastic shell as the earth path which will always fail at some point.

drp · Jan 6, 2023

The big problem with the Lucas turn signals is that the ground path uses the chrome plated plastic turn signal housings. The fix is easy, run small ground wires (20-22 gauge) from the socket mounting screws, through the headlight stem and provide a real grounding path (front & back). The other thing I would recommend is taking the turn signal switch apart (preferably over a dish or bowl to catch the springs and balls) and burnish the contacts with fine emery paper. I've had to do this periodically in order to keep my blinkers in good shape.

Lineslinger · Jan 6, 2023

Have you checked the reservoir? You may be low.

BritTwit · Jan 6, 2023

Does it work on both bulbs and LEDs?

lazyeye6 · Jan 6, 2023

LEDs are not installed

EstuaryBoy · Jan 6, 2023

Lineslinger said:
Have you checked the reservoir? You may be low.

View attachment 102562

It's called 'Optrex' in the UK

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