Motorcycle Repair: ignition, cb500 four, primary coils

Question
QUESTION: hey, i was wondering about something about my 72 cb500 four throttle/carbs, when i turn the throttle about 1/3 of the way i hear and feel a somewhat loud click, there isnt anything visual obstructing it, is this normal? i got this bike from a friendand it was sitting for about 15 years. not really comfortably taking carb assembley apart unless i need to. also there is quite a bit of rust in my tank, i was thinking of using CLR and some rocks to clean it out, is this a good way of doing it? if not can you recommend a better way? thanks a lot for your help,
Andy

ANSWER: I can't think of anything that would cause the clicking unless the linkage is rusted upside the adjuster housings.  The best way to clean the tank is with phosphoric acid and then seal the tank with Kreem.  If you use rocks, you may end up with dirt in the tank that will have to be removed somehow.  

Regards
Rich

---------- FOLLOW-UP ----------

QUESTION: thanks for the help, i have another question for you. i think my coils may be bad, i didnt think both would go out at the same time. i was told that since 1&3, and 2&4 fire at the same time, that i should be getting continuity between the two leads from each coil that lead to the spark plugs. i do have continuity in the smaller wires. also i tested the voltage coming off the bike into the coils and was only reading about 8 volts. i tested both pairs of leads from the bike after cranking it over about half a revolution. thanks again.

Answer
That's not the best way to test a coil.  The continuity between the black and white wire and the yellow or blue wires indicate that primary coils have continuity and that's good.  The black and white wire is the power into the coils and the blue and yellow wires go to the points and ground the coils when the points close. Make sure the coil mounts are grounded to the frame with a good ground.  I've seen the frame rust up in that area causing increase resistance.  THe high tension leads should gave continuity to ground.

I'd recommend you turn the ignition on and then manually ground the yellow and blue wires and see if the plugs don't spark when grounded to the head.  If they do, the problem is probably in the points or point wires.

Regards
RIch