by Stephg

Harleys since 1991 have come with self cancelling turn signals. Some folks with older bikes would like this feature as well. But hooking up the modern Harley module means a lot of work, adding sensors and a bunch of wiring you'll probably regret getting yourself into.

There are a couple of devices on the market that allow conversion to a self cancelling feature based on time. I have no personal experience with these devices, so if you decide to buy one of them, don't forget to tell me if, or how it worked out. This information is provided as a possibility for solving a problem, but is not an endorsement of these products. If they don't work as advertised, it's not my fault.

Kisan signalMinder™
Kisan's advertising claims that their signalMinder™ not only makes your turn signals automatically stop flashing after a user definable 15, 30, or 45 second duration, but can also be configured by the user to convert turn signals into running lamps. They also make headlight and taillight modulators, a tire pressure monitor (you have to read the description to believe it) and what looks like a voltage guage for monitoring your charging system (though there's no info on it yet on their web site).
          Kisan Technologies

Signal Dynamics
Signal Dynamics makes an automatic cancelling turn signal module which varies the time the signals will continue to flash by how long you initially depress the turn signal control. Hold it for one second, the signal will flash for 7 seconds. Hold it for two seconds and it will flash for 20 seconds. Hold it for four seconds and the signal will flash for 75 seconds.
          Signal Dynamics Turn Signal Module

They also make headlight modulators and brake light flashers.

Badlands
Badlands also makes a self cancelling turn signal control. This one appears to have a fixed flashing length of 7 seconds.