'77 XS360 Key Sparking While Riding!!! Inconsistent Running

[Leandro360]

I am new to the forum so first of all I'd like to say hello to everyone! Hoping you guys can help me get my bike running. It's a 1977 XS360 I just got with 300 original miles on it and right now I'm just trying to get it to run smooth. I've had the carbs apart and cleaned them, new plugs, and a new battery. I got it started after kicking it for quite a while. Sometimes it feels like the kick starter is just going through mashed potatoes and it always takes a long time to get it started (there is no electric start). I had a few successful rides on the thing with intermittent troubles. Sometimes it would start to backfire and sputter. The other day I was riding when it was starting to get dark and noticed my keys sparking on the handlebars! When I was checking with a multimeter between the frame and the key while the key was in the on position it blew the main fuse. I appreciate any ideas you guys might have as it's 50 degrees out for some reason and I'd love to get a few more rides in this winter!
Thank you all for your time.

 

[BBS360]

Welcome to the forum! Sounds like a cool find, only 300 miles. Maybe the previous owner had the same problem and gave up?

That's an odd one though. Take the keys out while you ride?

Could be a loose wire inside the key switch conducting to the key cylinder rather than the body. The cylinder doesn't connect to ground so the keys to the bars would be the only ground path.
Disconnect the key switch connector and check for continuity from any of the wires to the key cylinder with the key in the run position. If any of the wires do have continuity, or less than infinite resistance, then there's probably a loose connection inside.

How's the rest of the electrical system behave? Battery charges well?

 

[Leandro360]

Hey thanks for the response, I took the kill switch apart today and it was all corroded inside so I just bypassed it, the bike seems to be running a lot better. Think there's any chance that the switch problem could be the cause of the sparking? I took the key off the keychain for now so it doesn't spark but I've gotta take it all apart probably

 

[BBS360]

I happened to have my lock assembly off the bike already so I took it apart.
Once the spider eggs were cleaned out it looked like it wouldn't take much for corrosion or a loose wire to energize the lock cylinder and key.
Worth a look.

 

[Leandro360]

I had it all apart yesterday and I too had a small spider village inside! I also found this nice little "fix" inside, previous owner must have been in there.


I fixed that and was hoping for everything to go right back to normal but now I've got nothing when I turn the key. As soon as I fix a problem out pops another one haha, but the thing's damn near 40 so I can't complain, still loving the bike.