Sparking points

[Biz]

My latest "strange problem" on my CA95 is when I kick it over or open the points manually, the points spark quite a bit. Big yellow sparks. I suspected the condensor, so I removed it and checked out on a capacitance meter, it reads 0.26 uf which is in spec. DC resistance is OK. So wondering how much sparking is common. I would expect some small arcing but not this much. I usually convert any bike (like my Yamaha RD) with points over to electronic because of crap like this. The arcing actually seems less with the condensor removed.

But the good news is I am ready to attempt to start it, after about 25 years of inactivity! I stopped when I saw the arcing.

Biz

[Jetblackchemist]

I'm not sure how much sparking is common on these, however if it is sparking when the points are open then you have a bad condenser. If all your wiring and grounding (best on non painted bare metal surface) is correct, then I would make sure the point gap is gapped, cleaned, wired and timed correctly. If after that you are still getting bad arcing, then I'd just replace both the points and condenser to be safe even though you could get by possibly with just a new condenser.

The condenser acts as a weak capacitor storing current, when the points start to open the current looks for a path to ground, the condenser acts as a ground and keeps it from arcing across the gap to keep the points from burning up. Since it seems to work better minus the condenser when it should work better with it, logic tells me its the condenser even though it is in uf range it is still malfunctioning because it isn't doing its job.

[Biz]

Thanks jetblack. I'm familiar with the theory, being an EE for 30+ years, but I need to look more into why it sparks so much with a supposedly good component. The wiring is a good suggestion, and I haven't filed the points yet. I've also borrowed a couple different size capacitors at work, .1 and .33 uf to see what happens if they are used instead.

[Jetblackchemist]

No Problem, There are two usual causes of point arcing one a condenser going bad, and especially, any form of oil/grease/dirt impeding the ground in the points and or condenser mounting and their plate.

Also, if the coil starts going bad, it starts changing its resistance, that can cause condenser failure and arcing. The system should not use resistance wires, or resistance spark plug caps their resistance should read zero to 5k ohms max.

Try to maintain .014" point gap at all times...if you move the base plate to adjust the timing that can effect the point gap a few thousandths, and changes the point open moment which should open at the "F" mark, the service manual has it backwards saying closed at the "F" mark.

Ignition point faces are tungsten coated, and should not be filed to renew their contact surface. If the points surfaces are pitted, replace the points, and the condenser, and clean the mounting of ALL the plates and screws/holes with contact cleaner, then let dry.

I understand what you mean with the capacitor, tattoo machines use a 43uf to prevent bad sparking and arcing between their contact points as well as have some return current in the circuit when the points are open, in essence to trick the machine into functioning as if the circuit never was open. I would try the above steps before trying to replace the condenser with a capacitor.
~Jim

[Biz]

Made a little progress today. The sparking was apparently caused by oil or dirt on the points spring. Cleaned with contact cleaner and that fixed it.
Next the points gap was set to about .022 so got that set to .014".
Now as I check the timing, it is set to the mark after "f" which I think is TDC. So that's next. One problem at a time. Somebody obviously didn't know what they were doing cause I doubt it will ever start like that. Thanks jet-black for the help.

[Smithers]

Great to hear the problem is long gone. Yeap dirt and oil screw up anything. Very good info JetBlack, you're the man.

[Jetblackchemist]

No problem, I love it when problems get solved...glad I could help.
P.S. Sams the man