TOPIC:

So I picked this bike up recently, it's a 1979 KZ 7750 twin that's been hardtailed and bobbed. Cleaned and rebuilt carbs, tank is spotless, has spark and compression...although not measured yet with gauge. Bike wants to start but wont. Backfires out of carb inlets too... carbs get wet and suck when blocked. I figure it has to be a timing issue right? So I open it up today and notice what I have and what I should have are different. Is this gonna be an an issue? Any thoughts or ideas appreciated...Thanks!

Do you see blue sparks coming from the points?
Looks like a 69 F 250 condenser would work if so.
Steve

I've got blue spark from new plugs but it seems weak. Gaps ar correct though... as far as condenser spark what am Iooking for exactly? Never worked on points before.

There should be no sparking at the points. A little and it will still run but a lot you won't get any spark. Check if the points are pitted. You can clean them up with a nail file and a folded match book to clean off any oil or debris.
Steve

I'll check that tomorrow and give it another go... last ditch before taking heads off and looking at valves which I do not want to do.

Looks like your points plate is too far over. Try putting it back where it was in the center of the grooves and try it again. The points should just be opening at the F mark. Check that the spark advance moves freely as well.
Steve

Ok so I used some 1000 grit paper to clean contacts which then started throwing spark after ward. I shifted unit to center and spark lessened bit still visible. Also turned crank to verify points were opening at timing mark and they are...not all the way but slight enough to get paper in there but less than the appropriate spaces gauge. You mentioned a condensor....what is that about? Like I said electrical is FAR from my strong suit. I can turn a wrench with trial and error but electrical os another story....

The condenser is attached to the points so when they open there is no spark at the points. Pic of your plugs?
Steve

If the condensor is weak or end of life you get a huge sparks with every opening of the points.
A good condensor compensate the current drop at the opening so there should not any or less tiny sparks at the points.

You can think of the condenser as a delay.

When points first come open (without a condenser), a voltage spike of several hundred volts appears on the points. Normally this would result in an arc at the points that would sustain even as the points open. This would bleed off the spark energy from the coil. A condenser is a small storage device which has to fill up with charge in order for the voltage to rise. This limits the rate at which the voltage can rise, thus delaying the voltage spike. So you can think of the condenser as a delay device. It prevents the voltage on the points from immediately rising to several hundred volts. This delay allows the points to open far enough so that when the voltage spike does hit the points, they are already too far open for an arc to jump across.

This alleviates arcing due to the inductance of the ignition coil. But there is also a tiny bit of arcing that would happen simply from the opening of a switch passing current because any current has a tiny bit of induction to it. This little spark can often be seen and will still be there with or without a condenser, but is very small.

loudhvx

You explained it perfect as i never can explain with my poor english knowlege.