The alternators on the XS650 are a well known weak spot as they they don't generate enough power, Zip at idle. Frequent stop start riding usually resulting in a flat battery. The alternator has an electro magnet spinning inside a stator. Brushes are mounted on the stator cover which supply power for the electro magnet. Quite a silly setup in my opinion, the brushes don't necessarily present problems, just the low output does.

I put the multimeter probes over the system and found everything reading within specs, but still I didn't like this system, so bought a permanent magnet rotor, an internal stator and a combined regulator rectifier off ebay for an all up cost of around $130. Kits are available with exactly the same parts, but sell for $500-$600 and they come with an adapter to fit the stator to the engine cases. Damned if I was going to pay that amount!

The parts arrived, so I took some measurements and spun up a mount for the stator from two bits of aluminium and also stepped a 6mm woodruff key down to 5mm to fit the XS keyway. When I fitted the key to the shaft I found the diameter of the key was larger than the keyway diameter on the crankshaft, no good! I then turned up a piece of stock to the required diameter, cut it in half and stepped it - perfect fit. The stator mount was made in two parts as I didn't have a piece of aluminium of the right thickness, around 45mm from memory. The magnetic field of the rotor dictates the positioning of the stator, so I mounted the stator inside the rotor, fitted it to the crankshaft, took some measurements and from them spun up the mount.

Everything fitted up great, but, the original rotor had marks on it for timing, as the new rotor was for a Banshee and the stator for an XV, there weren't any marks. So I fitted the original alternator, timed the engine, then carefully removed the assembly and replaced it with the new alternator assembly, made up a pointer plate which fits in the side panel and scribed lines on pointer plate and rotor.

When I finally got around to starting it to test my mods: Alternator, single points, cable splitter, wiring, it started up straight away, the timing was spot on and the single points timing was also spot on. Alternator output was 14.4volts right from idle, as opposed to the original alternators output at idle - zip!

Video is in the video section.
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