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Thread: tired of faulty points

  1. #1
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    Default tired of faulty points

    Been 12-volt on my Chief for about 15 years, and I'm tired of getting faulty points. It's gotta be better than this.
    I always use a 12-v coil that says "internal resistor", or "no external resistor required". I've heard it said that a resistor is still a good idea regardless of the coil's claim. Auto parts folks come up short for me on availability of resistors, advising me to "go to a salvage yard and ..". I've tried a few resistors, but am not confident that they have been the answer (spotty history of experience).
    I've also tried the electronic breaker, and was impressed by its dependability, after a night rain for instance. But mine failed due to an ammeter that corroded and lost voltage until the amperage burned out the breaker. Felt a little chagrinned about spending another 200+, so went back to points. But I'm going to try it again.
    Still (and I searched the subject here, no results), I'd like to read some discussion on the subject of FOULED POINTS.
    Can anybody help me?

  2. #2
    Join Date
    Dec 2010
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    Default

    A few thoughts... more from old car experience than bikes...

    Lots of points sets now are tungsten, not platinum. Older or NOS platinum points are far superior.

    You need to clean points with a bit of emery/sandpaper/400 grit regularly. Every couple of weeks. They do fur up. Doesn't take much, but especially in a damp climate or unridden, points corrode fast.

    Ballast resistor is a function of not burning out your coil... not your points. A condenser is required for points, period. The first thing I always replace is a condenser, because modern condensers are sh**. First thing to do is put on a good, correct value condenser.

    If your coil is failing, that requires an external ballast resistor, to reduce voltage from 12 - 8 or so... which is what a lot of 12V coils really require. But if it says No External Ballast required... that's what it means. You don't need a ballast resistor. But you will need a correct condenser and you will need to keep your points clean.

    See if you can find NOS points. The platinum is massively better than Tungsten. Regardless, the points file (or bit of emery) that everyone carried in their vintage toolkits back in the day was there for a reason, not just to impress judges that your toolkit is complete. ;-) Points files are included with toolkits for a reason!!!!

    As I don't generally get to ride my old bikes/drive my old cars every day, I always clean points as part of pre-start routine.

    Hope this helps....

  3. #3
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    Filibuster!

    Its about the condensor, not the points.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  4. #4
    Join Date
    Jul 2012
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    Quote Originally Posted by sirhrmechanic View Post
    The platinum is massively better than Tungsten.
    I hate to disagree, but...

    Pt was supplied for magneto points way back in the Middle Ages because people (incorrectly) thought back then that the fact Pt didn't oxidize made those points better. In principle, it's correct that they oxidize much more slowly, but in practice the difference is irrelevant. It takes years of non-use before the oxide on W builds up enough to be noticeable, but the first sparks across the points burns it away anyway. The real issue for why Pt is worse than W for use on a motorcycle is Pt forms a brittle carbide with any oil vapor that's present (and, on what old motorcycle isn't oil vapor present?...) causing the points to rapidly erode. Today, the only reason to use Pt is because of the placebo effect of people who believe they work better. They don't.

    Quote Originally Posted by sirhrmechanic View Post
    You need to clean points with a bit of emery/sandpaper/400 grit regularly.
    Again, I hate to disagree, but... As for the ritual of burnishing your points with emery paper. it's not only completely unnecessary, it's actually possible to make things worse by leaving grains of the abrasive between the points.

    Quote Originally Posted by sirhrmechanic View Post
    the points file (or bit of emery) that everyone carried in their vintage toolkits back in the day was there for a reason,
    Here I agree there was a reason. But, I disagree on the reason. Unless the value of the condenser is "perfect" a pit will slowly form on one point and a pile will form on the other with use, due to transfer of the material from one point to the other by sputtering. The reason for the points file was to remove the pile, not for regular burnishing, which is totally unnecessary.

    But, by all means use Pt and regularly burnish them with a points file (not emery) if it doing so makes you feel better. For me, though, using W points and not burnishing them results in an electrical system that functions every bit as good as with Pt. With the added advantage that it saves wear and tear on my knees by not having to crawl around on the floor performing Medieval rituals.

  5. #5
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    Thanks fellas! Geez I'm proud to be humble, or we'd be in ignorant bliss during those medieval acts! Rites of passage, but passage means graduating out of that someday, doesn't it?
    Condensor, I remember some talk about the condenser, in magneto discussion. And I think I'm using a DR 90 by Standard Blue Streak. If he's the culprit then I'm due to curse him again. .. unless I get the breaker installed. But being a skeptical cuss means that a little study is in order for the BEST components in that system.
    Full disclosure: I rode the side hack about 30 miles in a moderate rain, got soaked, jacket weighed a ton. and I made it home, sputtering the last mile.
    Thanks again, let's go a little more,... please.

  6. #6
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    Quote Originally Posted by fillibuster View Post
    And I think I'm using a DR 90 by Standard Blue Streak.
    That's a common electrolytic capacitor. It's perfectly fine, but although some might last as long as 40 years you can't count on a lifetime of more than a couple. Back in the old days you changed the condenser as a matter of course when you changed the points so there was no reason for manufacturers to spend even a few cents extra to make them last a long time. For only a dollar or so it's possible to buy a modern capacitor that will last essentially forever. The same type of capacitor I recommend for use in rotating armature magnetos works great on a points ignition system (although usually with a somewhat larger capacitance):

    http://www.britbike.com/forums/ubbth...762#Post508762

    If you look at your points while the engine is running and you see anything more than tiny pinpricks of light, either your present condenser is bad, or it has an incorrect value. And, vice versa. If there are only tiny pinpricks the condenser is fine. It's one case where electrical test equipment isn't required to do an electrical diagnosis.

  7. #7
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    Jul 2003
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    Rocky Top TN.
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    When Harley first went to electonic ignition (1980 I think) a lot of owners would convert back to "points type" ignition. A lot less money than replacing the electronic unit which failed often. Then the problem would be like yours, points would "burn up" in a short time. The problem (back then) was the coil needed to be replaced also. the electronic coil had a lower ohm (2.3 I think) The points called for a 5 ohm coil. This solved the problem. Because of this I will suggest to make sure you have a coil for a points type ignition.

  8. #8
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    Agreed, emery should never be used on ANY electrical device. The results can be disastrous, as the abrasive used in emery is electrically conductive. Anytime an electrical device is "dressed" it is extremely important to thoroughly clean the dressed surface due to minute particles conductive in nature being left behind. This can be hard to do when cleaning points on the road, remember when you clean and gap them on the road and blow them out with compressed air from your lungs, this is a field expedient and proper servicing should be done at the first opportunity.
    The function of the condenser is to quench the DC arc. When a condenser fails closed, shorted, you stop dead. When they fail open, loose their capacitance value, you still run but your points burn, pit, prematurely. Changing the condenser was always cheap insurance when doing a tune up but most of the time was not really necessary.

  9. #9
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    Use care when filing platinum points as they are soft,they were mainly use for mags due to low resistance.

  10. #10
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    Quote Originally Posted by tomfiii View Post
    platinum points ... were mainly use for mags due to low resistance.
    Although that is commonly said, it isn't correct. In fact W has an electrical resistivity half that of Pt, i.e. W is a better conductor. However, no matter what, the resistance of the points themselves is negligible compared with the rest of the electrical circuit. A pair of points ~1/8" dia. x 1/8" tall has a total resistance less than a micro-Ohm, whereas the coil is ~1 Ohm.

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