XS 650 ignition issues

[tooltime]

Hey all, I have a 79 XS that I have been trying to put back together for a buddy of mine.  He gave it to me in pieces.  He also has other XS bikes and that might be my problem here.  I have been trying to get my head around the wiring harness and I'm 99% sure what the problem is.   I have a bike that has a combined double coil, like the ones that you find on a newer XS with an ignition unit,  and the engine has points.  I have been trying to figure out where to plug in the point to, seeing how the wiring harness has no provisions for them.  So, I wanted to know if the XS ever used points and an ignition unit or do I have the starting of a frankinstine bike here and need to get a coil pack and wire harness to match the engine.  I have the frame and engine numbers if that could help.  I tried to look them up online and had no luck.  Engine is s650-207763 and Frame is 2F0-211085.   Let me know what I have here.  I'd love to see what this thing can do.  Owner said he had it running,  I find that hard to believe with what I was given.  Thanks for your time.

[grizld1]

Welcome aboard!

You're on the right track--the ignition's been messed with. Sure your buddy had it running--but before or after he did a mix 'n' match with the iggie? The XS650E (1979) used two single tower coils and breaker point ignition with one point pair per cylinder. Make sure to check what's going on with opening and closing of the points; the PO could have done an incomplete installation with a dual-lobe point cam from Mike's XS and a dual tower coil (something I don't recommend, due to frequency of manufacturing errors in the dual lobe cams).

[tooltime]

So there is a mod out there to mix the two together, is that what your saying with the Mikes mod?  If so, I don't see where the points plug into the harness at all.  The usually go to each coil, I pulled the points cover and each wire goes to one set of points.  One is orange and one is white.  Making me beileve that one goes to each coil.  Anyhow.  It's nice to see that I'm not loosing my mind.  So I must have a different wire harness, and the dual coil pack has to be switched out to two singles.....if I'm thinking correctly.   The quest continues.....I love getting other peoples nightmares!... Thanks for the help..Matt

[grizld1]

Count your blessings, Matt; you got hold of the scoot before your pal had a chance to butcher the harness! If what you're looking at is an incomplete installation of a dual-lobe points cam ignition, only one set of points would be used, opening the same set of points every 360* (or 180* at the camshaft). That setup would use a single coil throwing a spark to the cylinder coming into the power stroke at the same time as it throws a waste spark to the cylinder coming into the exhaust stroke. To check the points cam just hook up a continuity tester or ohmmeter to one points set and turn the crank by hand, watching the crankshaft marks. If the points set you're hooked up to opens every full crank rotation, the points cam has been changed. If it opens only after two rotations of the crank, you have the original points cam. The XS650E used the same ignition as all earlier models. My advice would be to use the original system with two coils.

[tooltime]

I'll check the points to see how they fire,  my only concern now is where do the points hook up to on this wire harness..  I'll try to send some pictures to show you what I have and see if it makes sense.  They say picutures are worth a thousand words....and some of those words are the four letter ones.....I know, cause I used them all while working on this thing.   Thanks for your help.  At least there is some light at the end of the tunnel!!!!  Matt

[grizld1]

Yeah, Matt, where the ignition is concerned the wiring diagrams are about as easy to straighten out as a well-tossed plate of spaghetti. Let's start with the basics.

Each coil has two primary terminals--power and signal. In the original color scheme, the power wires are red with white stripe. That's the code for kill switch power. Hook both power side primaries to the R/W wire.

On the signal side of the coil the connection does a "Y," joining a coil wire, a breaker point wire, and a condenser wire. Nominally the right cylinder coil is powered by the upper points set, but error in installing the automatic timing unit can turn that around. Just make sure that you're hooked up so that points are opening on the cylinder that's coming into the power stroke; if in doubt, attach your ohmmeter to one points set. When it opens, continue turning the motor by hand to TDC (rightmost stator mark), remove the exhaust valve covers, and try to wiggle the rocker arms. One rocker will be tight--that valve is open, and the cylinder is coming into the exhaust stroke. The other rocker will be loose--that valve is closed, and the cylinder is coming into the power stroke. Be sure that the points set you observed is hooked up to the coil that's hooked up to the cylinder with the loose rocker. Color codes for the signal side wiring tend to be erratic at best due to mix-and-match maintenance, but you'll find a free download of the factory manual at www.biker.net . Thanks again to Jean Akers for that service to the community!