Trying to gap the points (76 CB750F) and found the one set was bent. (maybe tried to screw it tight without the pivot pin in place)
So for 16$ I decide on new ones rather than dig through my collection of (likely) worn points.
Question: Do I need to spend the extra 16$ for new condensers?
FWIW my old points were in very good shape. Do condensers really need changing with each set of points?
Do you have the ability to test the condenser? Points are mostly voodoo to me and I often replace with electronic ignition but in general, I don't like old capacitors. They like to fail. How buried is it in that bike? I would probably replace while you are open but if it's not that hard to get access, you could test the condensers and if they seem okay try and run them.
I am assuming you don't have an LCR, ESR or EPR tester (if you had one, you'd know). If you have a multimeter that can test capacitors, you could try that. From a random internet source (CB750K | SOHC/4 Owners Club), you are looking for 0.20-0.24 mf.
Here's a test procedure using an analog multimeter (with a battery, an unpowered analog meter will not work) to charge and dump cap. That will tell you if it's still a capacitor (condenser in engine speak) but isn't a definitive finding of goodness. If it can't do this, it is definitely bad.
Trying to gap the points (76 CB750F) and found the one set was bent. (maybe tried to screw it tight without the pivot pin in place)
So for 16$ I decide on new ones rather than dig through my collection of (likely) worn points.
Question: Do I need to spend the extra 16$ for new condensers?
FWIW my old points were in very good shape. Do condensers really need changing with each set of points?
An automotive condenser is a pretty simple device. It is a strip of tinfoil and a strip of insulation in a can.
If it doesn't go to ground you're good.
If you're ever "stranded" with a bad condenser, remove it... which is how you test to see if you have a bad condenser on the road.
All the condenser does is lessen/reduce the amount of spark at the points so the points last longer. The bike will run without issue with no condenser(s), you'll just burn the contacts off your new points in about an hour.
SO: The two conditions of BAD CONDENSER
Condensor goes to ground: no spark
Condenser has open circuit: more spark at points
I have always changed points and condenser together -- not because you have to, just because condensers mostly fail with time, so changing one resets the clock.
Honda still sells OEM genuine points and condenser (whole points plate for that matter). Replace with genuine and you're good to go for another decade or two..
An automotive condenser is a pretty simple device. It is a strip of tinfoil and a strip of insulation in a can.
If it doesn't go to ground you're good.
If you're ever "stranded" with a bad condenser, remove it... which is how you test to see if you have a bad condenser on the road.
All the condenser does is lessen/reduce the amount of spark at the points so the points last longer. The bike will run without issue with no condenser(s), you'll just burn the contacts off your new points in about an hour.
SO: The two conditions of BAD CONDENSER Condensor goes to ground: no spark
Condenser has open circuit: more spark at points
If there is continuity it is definitely bad. You should have no continuity from lead to case. It can be in a failed state that doesnt show up in a continuity test (high resistance but still leaking, only breaks down at higher voltage, etc).
The second part of bitzz's test is slightly harder to check. That could happen if the lead wire broke. For that you need to charge and discharge the capacitor to make sure it is still a capacitor. The post I put above has a number of ways to check that.
This seems extremely straight forward. That said what's another 16$ when I'm in this deep.
Adjust a multimeter to the ohms setting. Touch one of the multimeter probes to the metal side of the condenser and the other probe to the terminal connecting the condenser to the points. The multimeter should read several megohms, drop to zero and then start rising until the reading returns to several megohms. Reverse the probes and you should get the same results.
1) Place meter on 20m OHMS
2) Place 1 lead on cap body (metal) and the other lead on the cap wire. The meter should climb 0 to about 20 in 3-4 seconds, then go to 1 and stay. If it shows 0 or immediately shows a reading near 20 or goes straight to 1, I'd say bad.
1) Place meter on 20m OHMS
2) Place 1 lead on cap body (metal) and the other lead on the cap wire. The meter should climb 0 to about 20 in 3-4 seconds, then go to 1 and stay. If it shows 0 or immediately shows a reading near 20 or goes straight to 1, I'd say bad.
There is no rule saying you change them all together, back when points and condensers were popular a set costs $3-5 so I always did them together. There is no rule saying you change them all together, back when points and condensers were popular a set costs $3-5 so I always did them together.
Your bike has 2 sets of points and 2 condensers (I think), and I suspect each of the 4 pieces is $15-20 these days. Might be worth thinking about an electronic setup -- you can get them for about $100 off ebay, that upgrade should outlive you and have zero maintenance.
If you choose to stick with your points, they are not voodoo magic. Things I always do:
1) Make sure you have good screws on the plate and condenser.
2) Make sure the points are clean and have no arc damage before setting the gap.
3) Before buttoning up, double check the points gap, then check for a good continuity between the capacitor case and ground. I`ve seen grounding problems with caps cause problems with old Honda Goldwings, never had trouble on my CB.
Checked them and a number of others that I had. Most tested just as you said. One of them was suspect and I've decided for $16 I've come this far what the hell.
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