For an
audible flasher reminder, install a 12V buzzer, one wire to the left flasher hot lead, another to the right flasher hot lead.
For a
simple turn signal system, find the green/yellow flasher relay wire and connect it to any 12V
two terminal flasher relay. Connect the other terminal to any wire that has power with the key ON. Tape up any remaining wires. Everything will work as well (or better than ) OE.
For a simple 4 way flasher system, install a toggle switch between the left and right flasher hot leads,
the 4 ways will work when that switch is ON and you activate either flasher.
Note: If you only have one dash indicator light for both left and right signals, the dash indicator will not work when the 4-ways are on with this setup, so you could ride away and forget they're ON.
(some models have separate left and right dash indicators so they will both flash with the 4-ways on.)
The above mentioned buzzer won't work when the 4 ways are ON.
I converted mine to separate L & R LEDs to alleviate this issue, and for added bling.
One advantage of the OE 4-way system is that it can not be turned on without the key, but once it's on, you can remove the key and it will stay on. This could be practical if you want to go for help and leave the emergency flashers on but not leave the key in the bike. For simplicity and practicality, my flashers and 4-ways are wired to work without the key, on a separate circuit with its own dedicated 'flasher only' fuse. It hasn't been a problem for me so far.
EDIT: Electronic flasher units
will not go faster to warn of a burnt out bulb.
A lot of mechanical ones (not all) will flash fast with less than a 20W (1 bulb) draw and flash normal speed with a 40W + draw (2 blubs or more ).