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79 sportster 1000. no spark, power to coils

Started by mein207, April 14, 2017, 04:55:49 PM

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mein207

well, I picked her up a little while ago. been sitting for a long time. changed fluids, plugs and the normal stuff. ran ok, but not what I would like it to be. changed the front tire, fired it up. ran for a couple minutes and died. now no spark from coil. has primary power and the points are opening and closing, power to the points. checked plug gap,point gap, ignition timing, all show as they are supposed to. I suspect coil but don't want to just throw parts at it. ive looked online and there seems to be different ideas on how to properly check it. I know people don't seem to like this year bike, but I really like it for some reason. any help or ideas will be greatly appreciated. thanks, vince

Panzer

Lay a plug on the head with wire connected.
Ignition on and set the point closed.
Open and close the points with a piece of wood. (a pencil will do)
Try it several times.
You should get spark at the plug, you might even hear the spark snap....... if you don't, it's the coil.
As a Courtesy, post you findings.
Everyone wants to change the world but, no one wants to change the toilet paper.

Hossamania

Whenever I have problems with a point ignition, I change the capacitor. A cheap place to start.
If the government gives you everything you want,
it can take away everything you have.

FSG

the capacitor is in parallel with the points and it serves two purposes

1 - it reduces contact wear/pitting by quenching the contact arc when the points open

2 - provides the High Voltage ground for the secondary side of the coil

with a bad or missing capacitor you'll have no spark at the plugs

rider7816

Quote from: Hossamania on April 15, 2017, 10:51:52 PM
Whenever I have problems with a point ignition, I change the capacitor. A cheap place to start.

Yea, what Hoss said!  Or you can do away with the points and go electronic to get rid of all of your ignition headaches.

Frank

wreck74

It's not a capacitor, it's a condenser, it is a shock absorber for the points, (keeps them from burning up) yes they go bad, do what panzer said.

FSG

QuoteIt's not a capacitor, it's a condenser

in the early days they were called condensers, these days they are called capacitors, capacitor, condenser, same thing, call them what you like

Hossamania

I actually did mean condenser. Haven't worked with them for a while, but still remember to set points at .019", about the with of the cardboard in an old matchbook. Not sure of the new matchbooks....
If the government gives you everything you want,
it can take away everything you have.

Wicked

....and use the striker to clean the plugs  :wink: !  Young folks don't know what they're missing...  :hyst:

...sorry to get off post...

wreck74

0.32 for the plugs and 0.15-16 for the points, 0.19 is kinda wide.

Hal64hd

I have seen in the past, the leads to the points on the wrong side of the insulator and cause the ignition to be constantly grounded.

Hossamania

Quote from: wreck74 on June 15, 2017, 09:42:03 AM
0.32 for the plugs and 0.15-16 for the points, 0.19 is kinda wide.

That makes sense with that charging and electrical system. Automobiles usually have a stronger system. That's what I was basing my old measurements off of.
If the government gives you everything you want,
it can take away everything you have.