You are right about the 670 not putting out much power from it's charging system.... which is why I'm yanking the whole thing out (charging coils, voltage regulator, etc..) and am replacing it with an alternator.
I searched and inquired here and elsewhere to find examples etc but really didn't come up with much. I looked at the Vegas Carts pulley...they do make nice stuff, but IMO they're a little too proud of their stuff (cost wise...I'm a if I can make it myself i'll try kinda guy...
).
Here is what I came up with....
Bracket is made from 1/4 steel plate that I cut out. I grabbed the dimensions for the bolt pattern on the crankcase from one of the service manuals...and just prototyped out the rest on cardboard. Once I was happy with the results i cut it out of the steel plate.
The pulley I found on the internet (
https://phoenix-mfg.com/V-Groove-Dri...el_p_1564.html). I had to machine down the center hub so that it would just mate up with my clutch and not stick out. 1" bore and 1/4" keyway...exact fit for the 670 drive shaft.
The alternator is a knock-off Denso Mini i picked up from Amazon. It's a 35 amp version...but there are lots to choose from.
Anyway...I hope this gives you some ideas on what's possible.
Good Luck
Smokey