Spark questions

Oljo here again.On inspecting My Cam Timer and points and condenser I decided to try a new condenser ,Nothing.I put the old condenser back in it ran for a little while and quit.No spark since.I've adjusted point gap ever way it can be set.I'm reading you can smoke a coil.I just don't know how many ways.The coil reads 4.1 primary,22 secondary.The contacts look good to me and I've cleaned them.I'm getting a good 12+v to the coil and the same at the condenser.I've fixed a few bad connections.but don't see any more.When I turn the switch to on I noticed the main 20 amp fuse really warms up when the head light is connected and pulling about 4 amps.The original on and off on the throttle has been bypassed because of a broke top half of it.I'm following the wiring diaghram and it looks like the next thing to look at is the ignition switch.When I ohm from the hot to the ignition switich with the key off nothing .With the key on I got continuity,I'm assuming it's reading though the headlight? Any Ideas ,the more I do the worse it gets.I've never felt a fuse get that hot before and not blow.

I have an idea - How about adding your bike's year and model to your signature line so we can help you. Ed

Including information about bike year and model is helpful to viewers.

While it may sometimes be possible to comb through another member's various earlier postings among other threads in an effort to help guess what make and model is being asked about, I suspect that many members who are normally generous toward posting helpful replies will simply pass and move on without bothering to comb.

It's easy to put the information in your signature where it shows in all posted messages, past and future. And the signature may be changed whenever and as often as desired.

If wanting a signature showing information about the bike in posted messages, it's easy to do. Here's how:





Good Fortune!

Sorry.I thought about that after I laid down last night.It's a 1980 750 ltd twin.To add somrthing,is it possible to have good ohm readings on the coil and still be bad?

OLJOCLARK wrote: . . . is it possible to have good ohm readings on the coil and still be bad?

Yes, the coil may short when under load.

Here's how it's explained in the KZ1000 FSM:




Good Fortune!

If not already done, would try brand new spark plugs.

The coil is supposed to "charge" while its primary winding is grounded through closed points.

Opening of the points (ungrounding of the primary winding) is the event that supposed to "fire" the coil.




Good Fortune!

Thanks Patton .You must be an early riser too.Something else worrying me,when I replaced the condenser I wasn't sure where the connecter on the condenser went back correctly.Should it make contact with the coil wire or be isolated from it on the points connection? They are tied together now the way I see it ,one on one side,the other making contact with it through the bolt.This is probably wrong! Can you enlighten me on that?Youre illustrations so far have been great for someone like me!

The condenser pack is ONLY grounded through it's mounting screw bracket.
It's other end, with the wire lead on it, is supposed to be connected to the same spot as the leads to the points.
That would be the ungrounded, open end of the points.
When the points are closed, the coil's primary winding draws current and "charges up".
When the points are forced open from the cam lobe, the magnetics breakdown and the coil's secondary winding fires the plug in a high voltage discharge.
The condenser is in parallel with the points ~12v (primary coil B+ source) and then absorbs the fly-back energy from the coil moving AC (alternating current) through it.... supposedly absorbing the little sparks you might see, which can cause some misfiring if out of whack.

Thanks again.Whats the chances the coil was weak and I finished it off messin with everything?I'm sure I'm getting plenty of power to the coil now.Could I have killed a brand new condenser,or shorted the coil Myself?

OK,I filed the points,got the wires right and I have fire again,cranks and runs but with same symtoms.I also cut about an inch off the plug wires and rescrewed them,The copper I can see looks good.Still a weak spark at the points and intermittent,The spark at the plugs is a mix of orange,yellow and blue,not fat blue. Can I read voltage or amps at the points where the wires connect and determine anything while it's running?I've read so many post's where the coil was not the problem.Oh yeah, I noticed that when it back fires the points spark bigger.Thanks

With the engine NOT running and both the ignition on and kill switch in run:
If you have +12v at the coil primary, with the points closed, or something very low like 6-8v at the coil with the points closed.... I'd seriously start considering the coil is bad.
And of course a shorted condenser is a killer too... but I don't think it is.

The condenser is supposed to prevent sparking of the points. A little the bike can run fine, a lot it won't run at all. If the coils are shorted they could overwork the condencers.
Steve