Electrics 101 - WR426

I have a WR426 (no battery) and while I'm OK with 12VDC electrics in cars, I know very little about bike electrics.

I want to wire up a new computer fan to cool the rad. Fan is physically in place so now I need to hook up 12V. I'm simply going to run a manual switch in the circuit.

A mate says that my bike doesn't actually produce 12VDC and that the fan won't work because the old WR puts out AC power ? Is this the case ?

If the WR does actually produce DC current, is it OK to use the frame as an earth/return path (like the chassis ground on a car) or must I always hook up to an existing earth wire that returns back directly to bikes alternator/rectifier or whatever ?

What are my chances of frying the bike electrics by fitting the fan or other 12VDC devices ?

Anyone recommend good resources for explaining bike electrics in simple terms ?

Yes your friend is correct, the old WR426 is 12VAC. You could however hook up a rectifier just for the fan, which should work.

Trail tech makes a really clean regulator/rectifier that replaces the stock regulator.


I've checked out Rich's site and it's fantastic ! It even has some info pertaining to another Australian WR426 which is very handy.

I've wired it all up but can't get 12VDC out of the rectifier (I've tried another rectifier).

I simply added an extra wire from the black, regulated 12VAC wire powering the lights. This in turn is connected to the 'AC' post on the rectifier, with the diagonally opposite post connected to chassis ground (ie. the lights are still on AC power. The rectifier is in parallel with the lighting circuit).

Should I have my rectifier connected in series instead ?

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