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PMA conversion.

toglhot

Well-known member
Joined
Nov 20, 2021
Messages
153
Most bikes come with a permanent magnet alternator, so, right from idle the output is at it's max. For some reason, Yamaha decided on an electro magnet alternator for the XS650, so, very little output at low revs, the output increasing as revs increase. So if you continually start, stop the engine you end up with a flat battery. not much fun when tuning or working on the engine.

So I decided on a PMA conversion. These conversions are available from XS650 specialists, but they are around $600. That put me off, so I did a little research and discovered the Banshee has the same rotor taper as the XS650and a stator from an XV works well with the Banshee rotor. armed with this info I went on ebay and bought New Banshee rotor, an XV stator and regulator/rectifier, all for $120.

This only left the stator mounting plate. I've read a Banshee mount can be modified to fit with a hacksaw, but I didn't fancy a bodged up mount on my build, so I bought a slab of aluminium and machine one up on the lathe. The Banshee has a 6mm woodruff, whereas the XS6500 has a 5mm woodruff, so I simply machined up a woodruff of the correct diameter and stepped it.

This only left timing. So, I fabbed a pointer plate, installed it in the left side cover, installed the original alternator again, rotated the engine until the pointer lined up, then very carefully removed the old alternator, installed the new one and scribed lines on both plate and rotor. success, the engine started straight up and ran extremely well.

The system works well, 14.5 volts throughout the rev range and no more flat battery.
 

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MacMcMacmac

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Joined
Oct 21, 2014
Messages
1,591
Location
canada
Now put a proper series regulator like a shindengen sh775 on it so all your work doesn't go up in smoke.
 
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OP
T

toglhot

Well-known member
Joined
Nov 20, 2021
Messages
153
Nothing wrong with an XV regulator, never seen one go up in smoke!
 
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