All of a sudden . . . problems!

Hello all . . . this is my first post to this forum, but have been lurking and reading a lot . . . especially the last couple days!

I have a 1978 KZ650D SR that I purchased just over a year ago. The guy who owned it before me has replaced a lot of parts, done engine work, etc and it has ran perfectly for me . . . until just recently.

All of a sudden, it seems to be missing intermittently on cylinders 2 & 3. I experienced loss of power, rough running, and the occasional backfire, mostly at higher speeds or while under load. Seems to idle pretty well. I pulled the plugs and found the plugs in 2&3 to be blackened and/or wet. Cleaned them up and reinstalled. Checked the coils, which were replaced by the PO (Emgos) and still looked brand new . . . all good there, the resistance readings were right on the money on both of them (4 ohm primary, 25K ohm secondary).

I opened up and examined the points and condensers, which were also replaced by the PO in 2014 and I don't think have many miles on them. Tried to check the gap on them, I couldn't get the smallest feeler gauge that's in the correct range between either set. Also, the set for cylinder 2/3 arcs quite a lot while running, but the other set not at all. The points look to be in pretty good shape, but I'm needing to re-learn all this mechanical ignition stuff again, as I haven't dealt with points etc since I owned my old 1973 Camaro!

Wondering if it could be the condenser for the 2/3 side? Is it ok to just swap the condenser leads between the two sets of points and see if the arcing follows it? I plan to reset the gap on the points after seeing if it's the condenser causing my problems, but want to make sure I'm not going to fry anything by swapping the two condensers.

What do y'all think? Am I on to something? Any other suggestions to try?

As a side note, I've had fuel leakage problems with the petcock. Tore it down last winter, bought a diaphram replacement kit, turns out my diaphram is the one that isn't available anymore. I reassembled the petcock using some gasoline resistant sealer. That worked fine until recently, when it started leaking from the "sandwich" again. While I had the tank off checking the coils, I just removed the vacuum hose and plugged the petcock and the connection at the carbs. That seems to have fixed the fuel leakage problem. Until I can get a "real" manual petcock replacement, I'm just going to run on Prime and, hopefully, remember to turn it off at the end of my rides. Note that I did all this AFTER the problem above came up, so don't think that was a contributing cause. However, running on Prime, I'm assuming I won't get the "low fuel warning" and theoretically could ride until the tank is completely empty?

Sorry for the long ass post. Thanks in advance for any and all suggestions/comments. This is a great forum and I've already learned a lot about this bike!

Ron

Kinda answered your own question. Points, points and points again. Not likely to be the condenser with the info you have given. Get the points set right and clean, they shouldn't arc. Arcing points cause carbon build up and pitting to the points faces and consequently misfiring. Also if you have the equipment set the points dwell. These motor don't run badly in any respect unless there is a set up issue.
Black and wet plugs will be misleading caused by the points not charging the coils. Concentrate on getting the timing and the points right. Once they are correct then see if you have any further issues before ripping into anything else.
You don't need electronic ignition, one of my bikes has run on points since new and not given any trouble for the 41 years I've owned it.

A bad condenser will cause more arcing at the points which will prevent sparks at the plugs. Both condensers are the same internally, so you can swap wires if they reach.

But as Warren said, you will want to set the points correctly first.

When you disconnect wires to check or replace points and condensers, pay close attention to the location and order of the various washers. There are both metal ones and fiber ones. If not installed correctly, the points can be permanently grounded, resulting in no start.

If you dont have a dwell meter you can get it pretty close with a rigged up circuit tester. Two wires connected to a bulb. Connect one wire to the spring arm of the points, the other to earth. Turn on the ignition and turn the crank with the larger spanner on the crank end. The light should come on as the timing mark aligns for the points your working on. I.e. the timing is correct. Continue turning the crank and the when the light goes off the points are closed. That amount of turn is the dwell. If you look at the timing mark plate hole you should be able to see the timing mark for the other cylinders. If it aligns as the lights goes off you know the dwell is 180 deg. If it goes off before the marks align you know its 180 deg minus the amount you see. If it goes off after they align you know its 180 deg plus amount you see. Do the same for the othe set of points. Check your manual but from memory dwell for your bike is 180 to 195 deg.

Thanks for all the great help and suggestions, guys.

I do have a Clymer manual for this bike, so I'm not totally flying blind. But as to a dwell meter and timing light . . . no, not since I had a car with points ignition. Like I said, I'm having to relearn all this mechanical ignition stuff!

I reset the point gaps and swapped the condensers . . . now I have arcing on BOTH sets of points . . . doesn't run any better (or worse), but the bad plugs seem to have switched to the 1/4 side. I was using something similar to warren's method to check the dwell, but I was using a digital multimeter to check continuity, so it's a little tougher to "see" the point that you just lose continuity with it. At the point it should have been opening, my meter was bouncing around in the low single to double digits, so thinking that is good?

On closer examination, the point faces did look a little banged up. Also don't have a points file . . . I've GOT to visit my local tool store and see if I can still get some of these old school tools!

Anyway, thinking I just need to bite the bullet and find a new set of points and condensers. I see Z1 Enterprises still has points but no condensers and Parts N More has condensers but no points. Guess I will be placing TWO orders!

Thanks again everyone for all your help. Really appreciate it. This is a GREAT resource!!

Closely inspect the new points before installing them. The quality control from China is terrible. My friend ordered some that barely worked. It turned out the points pivot pin's hole was oval which allowed the points to move out of alignment while opening and closing. It took a while to diagnose and find that.

A finger nail file will work plus a folded matchbook to clean off any oil or grease. Be sure the springs are parallel with the plate. They can cause this kind of problem. Back in the day I used early Ford condencers tapped in and fastened to the frame. Wasn't a Kaw shop in 60 miles. :whistle:
Steve

What do y'all think of the electronic ignition setups? Worth the money? Can it be installed by someone with average mechanical skills?

I have the Dyna S. Easy to install.
Steve

SWest . . . did you also install Dyna coils? It has been recommended to me to do that . . . I have what look like brand new Emgos on the bike now . . .

Thanks!

I used the stock type coils until I got the Dyna 3 ohm coils. As long as they're 3 ohm or higher it will work fine. Adding the dyna coils added to the power draw. Not confident in Emgo anything.
Steve