Okay, third time is (hopefully) a charm. (Board ate my first try and I screwed up my second).
Listen to Hush -- he knows of what he speaks. :)As for me, I don't know crap about carbs. I do, however, know a little bit about the charging system on the 1982 CB650SC, which is the same as yours (I think). See, i.e.
http://forums.sohc4.net/index.php?topic=40792.0 and
http://forums.sohc4.net/index.php?topic=61075.0. See also, Kit's thread at
http://forums.sohc4.net/index.php?topic=42826.0.
It sounds like you have a charging problem, which is a known issue with these bikes. Here are some steps to follow:
1. Get the battery checked. It could be a bad battery, or the charging system may had ruined the battery. (Don't ask!)
2. Check the connection between the regulator/rectifier and the starter solenoid. (Honda calls it a starter switch, but it's a damn solenoid). If it is burned or buggered, replace it with parts from Tony Weeks at
www.oregonmotorcycleparts.com. Also, check the voltage output at the solenoid at idle and 5,000 rpm. You should get at least 12-13 volts at idle and up around 14 volts at 5,000. (That is from memory, so YMMV).
3. Physically check the stator and rotor and the wiring from the stator to the reg/rec. If little pieces of brown crap fall out when you pull the alternator cover, you should probably replace both the rotor and stator. (Again, don't ask!)
4. Put a multimeter on the stator terminals to the reg/rec. Clymer says 0.41-0.51 between any two yellow wires and no continuity to ground. If not, replace it.
5. Check the rotor. Clymer says 4-6 ohms between the two slip rings and infinite between either slip ring and the center. However, you can have an intermittent short which only ocurrs when the bike is under load, so make sure to do step 3. Also, while you're there, clean the face of the rotor with scotchbrite and DeOxy electrical contact cleaner (I get it at Fry's Electronics Superstore -- a dangerous place to go if you don't want to spend money).
If either the stator or rotor tests out bad, I'd strongly suggest replacing both. (Once again, don't ask!). I have bought both units (rewound) from
www.customrewind.com . Gary is a great guy who does good work, but he is not computer savy so you should call him on the 800 number and do the deal. I forget what I paid for my rotor, but the stator was $85 (plus my postage shipping my core back to him). Plug and play! Tell Gary that Lee King from Sugar Land, Texas sent you.
Any other questions, feel free to ask. It's the least I can do considering the great advice I've received from Hush, Kit, Hondaman and the other inmates here.
Lee
(I nearly fired my mechanic but I realized I couldn't afford to fire myself)
Hi mate, put 650 in your question line next time and we'll be right there. 
My 650 had a bad rotor, took me replacing all the other bits before I got to it and it still tested fine but was stuffed so hunt around for some 650 parts close to you and be ready to buy one.
Sounds like your carbs are flooding and that is causing the bogging down you describe, is yours the 650 with the plastic floats or the black shoe ones? the old black shoe ones you can reset but the modern all plastic ones have to be replaced.
More than likely your carb float valves are up for replacement, they are the tiny sharp tipped thingies that the floats push up into the carb body to shut the flow of gas off to the bowls.
My last set cost $40 for the 4 so not an expensive item and if you haven't done them since buying the bike they are well worth replacing so you can eliminate them from as the cause.
Floats are actually set below the bowls top lip so by all accounts carbs should never flood unless something like the valves are leaking in too much gas.
Get back to us on how you get on and welcome to the forum.
