Turn signals only flash at high rpm

On my 1973 Commando 850, with the headlight off, the turn signals will start flashing at about 1500 RPM. With the headlight on, that goes up to about 2200 RPM. I’m thinking about going to LED turn signals and relay in hopes that the lower wattage will allow them to start flashing at a lower RPM. Battery is new and fully charged. Contacts have been cleaned off. Your thoughts?

If there is nothing wrong with your indicators then your bike isn't charging properly,or a battery problem
What voltage are you getting at the battery when you rev it?

The flasher unit on these bikes is really poor quality - they only last about 47 years before they need to be replaced!


...joking aside though, they do get tired and wear out, so it is worth replacing.


The other issue is with the earth on the turn signal lamps themselves going through the stalks.
They rely on current passing through chromed plastic.
It’s worth running some extra wires up the stalks to the lightbulb holders, or at the very least give them a really good clean.

Check the voltage, report back

If they work well at higher rpm it's not the flasher or ground wires. Your alternator is either not putting out or connection to battery is bad. Charge the battery and try turning them on and see if they flash. If they do, that confirms battery and connections are okay. Do they work okay at the start of a ride then gradually go away. That would indicate that the alternator is not keeping the battery charged. If you are running an ei and have a charging problem you want to sort it out.

Thanks for everybody’s help! Turned out to be a bad connection to the battery. Cleaned the connections, tightened everything back up. Signals are working great! Headlight is much brighter! Alternator is putting out 13.75 V at 1200 RPM and 14.10 V at 2000 RPM. Whoo hoo!