Arcing on on set of points

[Supercoyote]

Hey,

Picked up a 1976 XS360 last winter, had to swap in a 400 engine due to the high cost of oversize piston and rings for the 360 motor, but just got it all back together after a new top end.

My problem is that I had replaced the coils (3.5 ohm EMGO units) and the points and I can't seem to get the arcing on the left side points taken care of. It runs quite well, first kick it immediately catches, drives nicely, but there are a couple minor problems that persist before I can get it safetied.

1. Arcing on just the left side points. The condensors tested within spec, new points. I had to adjust the gap slightly bigger than what is called for in order to be able to set the static timing. What's more important here if I can't satisfy both, the timing or the gap? One important thing to not is that in order to do the timing I have to disconnect the two point wires, otherwise I get constant continuity from the points wire to ground regardless of them being open, yet the bike still runs. My coils and condensor both test good, and I can't for the life of me find any wires grounding out further upstream. Any common missed places? Also, my bike came with a braided grounding strap about 6 inches in length in addition to the main engine to frame ground. Anyone know where that one goes?

2. Like I mentioned, it idles strongly, but once it gets to 1200 rpm or so or lower, it cuts out. It isn't so much of a stumble as a complete stop. I suspect my charging system is bad, specifically the R/R, but whether this is due to the charging system not supplying voltage at low RPM or the arcing causing misfires. The battery gets fully charged before each test run to try to eliminate symptoms of the charging system, but the problem persists.

3. Turns signals don't flash, just light up. I'm only getting 8V to the turn signal leads, but i've gone through and rebuilt the handlebar switch, cleaned and deoxidized any connectors I could find. Plugging in an EP34 electronic flasher gives no lights at all, whereas the stock thermal relay at least clicks and lights up.

When I got the bike home I was pleased to find there's a decent forum of people working on these bikes. Coming from a Honda CB750 as my last project, having people who know more than you do and willing to help is a huge boon to having a project. Here's a picture of how she sits minus side panels

 

[Supercoyote]

Came on a little too strong for a first post? Nobody Has run into similar problems?

 

[BBS360]

Should idle at 1200 so if it's dying at 1200 you're not idling well.

There are charging system diagnostic tests in the manuals. Hard to say much there without those results.

Are you trying the new flasher with the autocanceller still installed?

Just a guess but the different resistance coils may need a different condenser or maybe add some series resistance to the coil primaries to bring it back within spec? Wouldn't explain why it's only arcing on the left. The connections for the left side are good?

The grounding strap should connect from the valve cover to the frame.

 

[Supercoyote]

In case anyone ever searches google with similar problems i'll update this with some answers.

1. My turn signal flasher was bad, along with my headlight relay. Don't swap in a three prong relay thinking it'll work because the last flasher was a three prong. Or just use one off a newer xs400 like I did. Headlight relay was bad, but you can jump it by going diagonally from bottom left to top right of the female wiring connector and just put a small switch if your bike won't start with the headlight on.

2. I finally broke out the multimeter and traced my grounding problem. With the kill switch on, my points have continuity across the contact surfaces. If I switch the killswitch off the lose it. Is this normal? I would imagine the points being continuous through the system someplace other than when they close would degrade the spark, but there's a lot of things I don't understand about points already so this being normal wouldn't upset any of my preconceived notions regarding point ignition

 

[NewHavenMike]

When I set the timing on my 360 I had the same problem with the points. The breaker point you are testing will stay open until you get to a compression stroke. My bike would also run fine at high RPMs but would not idle at all.. my timing was way too retarded. After I set the timing static and adjusted the points to the right spots, the bike really woke up. Make sure the battery is at 14v too. I don't think you get a charge on the bike until it's revving at a cruise speed.

Setting timing statically will be enough to get a decent idle and OK cruise. After that, you have to get a timing light. I used a Circuit Test Pen to set static time.

 

[Supercoyote]

So you had continuity through the points at all times unless you had the Killswitch off as well? I set the timing with the point leads disconnected in order to actually be able to use my timing light, but if it's normal to have to switch the Killswitch in order to do the timing, I'll reset the timing and see if that fixes me up.

 

[NewHavenMike]

I set the timing with the bike ready to start, just without the engine running of course.

The engine has to be running to set timing with a light.

Do you have a circuit tester? It's a must for static timing. You need to turn the engine over in one direction, you can't turn past the LF mark and then turn it backwards. You need to turn a full revolution.

 

[Supercoyote]

I'm not sure if I'm communicating my problem entirely. When the Killswitch is on with the bike off, there's continuity across the points regardless if they're open or not. So it's impossible to use a circuit tester since it will be illuminated at all times regardless of the position of the engine