TOPIC:

I have a digital multimeter, and know how to ask for help. The manual says I am supposed to have 75v at 4k, and that doesn't happen until I rev up to 5k.

I had to install a new battery, maybe this is why.

On a 200 ohm scale, the meter reads 00.8 in series with the 2 leads from the stator. Is this what this thing is? The meter with just the wires touching will not zero itself, it shows 00.4 on the scale, so I guess the added value is the 00.4, but what am I looking at?

The shop down the road doesn't have another 650 with the same setup I have, so now what?

Help please. . .

Your rectifier converts the AC voltage to DC to feed your battery.
Set your meter to DC Volts, and connect the leads to your battery terminals.
With the bike off, you should be seeing a little over 12 volts.

At 4000 rpm, the voltage should climb to about 14.5 volts, and then the voltage regulator will clip the voltage, so it won't go higher. If you're getting 14 to 14.5 volts to the battery at 4,000 rpm, then your generator is doing OK.

Since I have no idea WHY we are going through this exercise, I suspect it may be to fix a charging system?

IF so:
1. charge battery w/trickle charger. Make sure all cells are GOOD with a hydrometer (less than $5 at the autoparts store; get the smallest they have)

2. pull your wire that connects the stator (or alternator or generator) and start the bike (it will start fine with the charged battery if everything else is OK. Measure the AC on the two wires using the probes from the multimeter. If you got 68 VAC as indicated in the thread title and get that at 4K rpm, and the manual says you should get 75 VAC, that isn't bad and I wouldn't worry too much. Next step is to reconnect the connector and stop bike.

3. Put meter in VDC scale and start bike. Measure battery voltage at idle. Should be about 12.5 vdc and then rev to 3500 rpm and it should be about 14.5 vdc. Higher or lower, indicate problems with either the reg/rec (or if separate units, one of the two; most likely with the regulator OR very possibly a poor connection... clean those connectors and dab with dielectic grease before running off and buying a bunch of electrical stuff.