'79 XS650 Build project.

Remove the badge, put the side cover face down, ideally on a leather bag full of sand, but failing that whatever you come up with to give support but a bit yielding. Take a small ball-headed hammer and tippy-tap. Maybe some judicious use of wooden drifts too? I'll bet you can bring it to a good enough state. Or at least good enough to add some filler, rub it down and re-paint.

Nothing to lose . . .
 
So I took my bike for a ride to work yesterday, and this evening after I got home and it has cooled down, I checked my spark plugs to see how my fuel mixture was running. It was a little lean, so I backed out the screw a 1/4 turn on each side, but I then noticed something. I compared the plug to the standard BP7ES and realized that my plugs weren't just resistor type, but didn't have a "P". I have BR7ES instead of BPR7ES, which means my spark plugs do not protrude into the chamber as the stock ones do.

Is this a problem?

I'm willing to get the BPR7ES plugs to test the difference, but the bike runs pretty good as it is, but I haven't ridden it much to know if I am losing power.
 
So, just the other day as I was leaving on the bike, the horn honked several times, which indicated to me that the M-Unit was receiving high voltage spikes. I unplugged the PMA to stop any damage to the M-Unit, and that seemed to work. Today I plugged it back in and went a few miles or so before it started to do it again, so I again unplugged it. I ordered a new H4 halogen headlight to help draw down the wattage. I don't know if that will solve my problem as my r/r may or may not be shot. I will test the voltage tomorrow and see what I get.
 
Did the switchover to the H4 light, put the stock front turn signals on because they're all I had that fit, as the old LED headlight had them built into it. I did notice that my turn signal indicator ground wire had broke, so I fixed that while I had in there. So I started the bike and revved it up to 4-5k rpm, and got about 13-13.5v at the battery. The M-Unit didn't honk. However, to really tell, I'll have to go for a ride and listen for it. Because that's what happened last time. Maybe there was a short in the headlight bucket, maybe not. I'll let you guys know
 
Went for a short ride after installing the H4 headlight and stock turn signals. It seemed to go fine, but I did have a mishap where my coil live wire connector came loose, which made me lose spark. But I just taped the terminals to keep it from separating again
 
Update: been riding without issue ever since I switched headlight. Thinking about adding a fan to blow on the MOSFET regulator just as an additional precaution.
 
So I had put my bike in the garage last week and a few days later went to take it to work, but would not start. Later I found it had a very weak spark, even bought a spark continuity tester to verify I was getting power to the plugs. I traced the wiring to make sure everything was properly connected, checked the kill switch, and finally checked the coil. The resistance on both primary and secondary coils was as double the spec. So just need to get a new coil and see if that will fix the problem.
 
So I had put my bike in the garage last week and a few days later went to take it to work, but would not start. Later I found it had a very weak spark, even bought a spark continuity tester to verify I was getting power to the plugs. I traced the wiring to make sure everything was properly connected, checked the kill switch, and finally checked the coil. The resistance on both primary and secondary coils was as double the spec. So just need to get a new coil and see if that will fix the problem.
I suppose coils can go bad like that over a week or were maybe failing slowly. When you crank with the electric starter you are taking a ton of energy out of the system and the coils may be seeing only 9 volts. That means your spark will be 25% -35% weaker. Did you try kickstarting?
 
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I suppose coils can bad like that over a week or were maybe failing slowly. When you crank with the electric starter you are taking a ton of energy out of the system and the coils may be seeing only 9 volts. That means your spark will be 25% -35% weaker. Did you try kickstarting?
I did both, but I'm running a PMA system, and the coil tested bad for resistance. But kicking and starting had the same results
 
Replaced the coil, same thing. I don't know what's going on. I'm still getting spark, but it's very weak as it was before. I'm at a loss for what to do.
 
Replaced the coil, same thing. I don't know what's going on. I'm still getting spark, but it's very weak as it was before. I'm at a loss for what to do.
You could check with a spark tester - see how far the spark can jump. Takes the guesswork out of is it a weak spark?
 
Well, not much has changed since my last post. I've been busy getting my KLR650 on the road, so now that's finally done, I'm going to focus on the XS and get that running again. After some research, I think I may pull off the LH rotor cover and ensure the gap is correct for the pickup and timing tab.

Here's the symptoms:
With the spark tester, I'm getting an orange glow for every spark.

I'm the dark, I can't see the spark from the plug to the ground.

I've verified the kill switch works as it should.

I've run direct ground to the battery from the coil just to eliminate any bad ground possibilities.

The coil is getting power to it, but I just realized I never tested the voltage amount until I wrote this.

The relay clicks on and off like it should when I turn the key.

My thought is that the gap between the timing tab and pickup had increased, thus reducing spark. But I'm not sure if the pickup is just a signal or actually picks up the electrical current to make the spark. If it's just a signal, then the gap wouldn't be as significant, but if it does pick up the current to make spark, then it would matter quite a bit. It would make sense if it slowly vibrated away from the pickup only to make a weak spark. But that's just a theory.

I've replaced the coil and that didn't change anything. Same results.

I've tried different spark plugs, no different.

Let's hear what you got.
 
The motor itself needs a good ground too. And yes, voltage to the coils needs to be measured. Battery type and current voltage reading at battery?

What ignition system are you running and with what type coils? Is the power source for the ignition via the M-Unit?
 
The motor itself needs a good ground too. And yes, voltage to the coils needs to be measured. Battery type and current voltage reading at battery?

What ignition system are you running and with what type coils? Is the power source for the ignition via the M-Unit?
The battery is an AGM, and I'm running an HHB PMA/CDI. It's a single coil with dual outputs. The m-unit only operates the Relay that carries the current from the CDI to the coil.
 
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