Can filing the points too much make them useless? This is for a 70's ski-doo. The season is pretty much over, but I cleaned the points with a file, then adjusted them and went for a ride. It died after only a few hundred feet, and I have no spark whatsoever now.
I did file them quite a bit, is there any reason why filing points can make them go bad? They are adjusted perfectly, and are making full contact when closed. Should I go get a new set of points, there are two of them, and they are getting harder to get nowadays.
Generally filing has been working for decades, as a temporary fix. Some have used this temporary fix for years :D
New points have a coating on the contact surface, that prevents impurities, oxidation and other junk from building up. With time, and as a result of filing, the surface disappears and the contact surfaces pit, get dirty and stop conducting quicker.
A common underlying reason for fast points failure is overheating, caused by for example a coil that isn't wired through a ballast resistor when it should.
You should also replace the condenser, always when replacing points (they say). Condensers rarely go bad, but they can. If the condenser is weak or failed, it will allow "dirty" and weak sparks. A working condensor ensures you get a good, strong, single spark arcing between the points. And nothing going on in between sparks. The condenser needs to match the points and ignition system used. A quote from dansmc.com :
"The capacity of a condenser is measured in microfarads (0.2 microfarads being the average capacity) and that capacity is matched to the points. If there is a big build up of material on one of the points it means the capacity of that condenser is too big or too small for that set of points. If the negative point (grounded or stationary point) loses material, with the build-up on the positive ( Moveable ) point. The condenser capacity is too low. If the build up is on the grounded point ( Stationary ) the capacity is too high. "
Removing material from the points at the contact surfaces shouldn't affect their operation, from a geometry point of view. But if you file them, you need to file ALL of the pitting out, leaving no crater or peak visible. Just shiny, flat surfaces that meet each other dead square and make full contact when closed.
So... keep filing, and start looking for replacements because you will need them eventually.
You can check the capacitor fairly cheaply. Just buy a cheap multimeter from an electronics shop that measures capacitance. In Aust you can pick them up for ~ $40. If it measures around the 0.2 uf +- 10% thats ok. If a cap fails it usually loses all capacitance. Put the multimeter to read resistance, should settle on open circuit ie 100,s of megohms. If it does both of those it should be good.
Points should never be filed except as an emergency fix. Points are designed for the proper curvature to acheive good contact point tension. If you flat spot them, even a small carbon spot will interfere with the full current flow. You can polish them by pulling a 400 or 600 grit sandpaper through them under their own spring tension. If the pitting is excessive and can't be removed this way, then you need a new set and condensor. Even after polishing them you need to pull a piece of cloth etc. through them to remove any sand debris. One piece of sand will stop the engine.
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