Noob here, 1972 xs650 not firing on right side

Belle said:
They aren't in the same cycle at the same time
Click to expand...

In other threads on this forum, others recommended swapping coil wires side to side for troubleshooting, stating that each fire at the same time. That's what caused my confusion.
 
On TCI and pamco ignitions they have what is called a wasted spark type system so both cylinders have spark at the same time on both the compression and exhaust strokes. On a points type ignition like yours it has a set of points for each cylinder so only one cylinder has spark at a time unless it has been converted to a single set of points and a double lobed points cam. When people suggest swapping plug wires it is on the wasted spark type systems.
 
Well I got her fired up!! :D I checked for spark on both sides and found I only had spark on the right side.. This really threw me off because that's the side that was previously giving me trouble. Finally found that one of the cables from my condenser to the coil was disconnected, hooked it back up and she started up. The right side is still running really rough though so I'm back where I started.. Since I will be changing to a pamco and replacing coil, plugs, wires and caps should I also replace the condenser? Or anything else? I figured I'd start with replacing electrical before tackling anymore carb stuff to rule it out
 
So now that It'll fire up should I switch coil cable from side to side along with spark plug cables to try to get an idea of what's going on? If the problem moves to the other side what will this tell me? Bad coil? Bad condenser? Both?
 
Once you have a Pamco, you won't use the condensers anymore. If you want to test them now, switch their wires like I told you earlier. If you want to test the coil/plug wire/plug cap assembly, switch the points wires running to the coils, then swap the spark plug wires side to side. Both of these tests will switch which cylinder the components are powering. If the problem moves, then something's wrong with one of those components. If the problem doesn't change sides then you may have a carb problem or something wrong internally with that bad running cylinder (rings, valves, etc.).
 
Well I'm baffled..:wtf: I switched the condenser cables like you said, no change right side dead. And I checked for spark, no spark right side. Swapped plugs side to side no change unhooked and swapped cables side to side still no spark. Ok.. the coil for that side is probably shot, although I was getting some spark earlier today.:shrug: Now here's where I'm confused.. I switched the coil cables and swapped the plug cables side to side and checked for spark and bam! spark! However after putting the plug in and trying to start her up I get nothing..:mad: Could this be two separate problems? No spark on that side and something wrong with the valve or ring on that side?
 
I'm a bit confused as well. You swapped plug and coil wires and now have spark on the right. What about the left? Did the problem switch sides? That was the whole point of wire switching, to see if it would.
 
Yes the no spark problem did move to the left and I did get spark on the right after doing the switch you suggested. I just can't get it to fire at all on the right even with the spark on that side. Switch it back around and the left side fires right up, but of coarse the right side is dead because of no spark. I just don't get why I'm not getting anything on the right even when I know I have spark on that side by doing the wires switch. I mean It was at least running rough earlier yesterday... Now nothing
 
The cylinder could be just really, really loaded up with raw fuel from not firing. OK, so you've narrowed the problem down to something in that plug wire/plug cap/coil assembly. It could be as simple as bad connections between the wire and cap or coil. It could be a bad cap, wire , or coil. You can trim about 1/4" off the wire ends and make fresh connections. I like to fan the wire out like so before installing .....

PlugWireEnd.jpg


There are tests in the factory shop manual for the coils and plug caps. If you still have the original caps, best to just replace them with NGK 5K Ω ones.
 
Ok, I will try this. I did noticed that the coil on the right side stayed cool to the touch while I had it running and the left side (the side working) was warm. I don't know if that means anything?
 
Ok here's where I'm at. I trimmed and made the plug wire connection like your picture above. (Thanks for the pictures btw really helps). I can switch coil wires and plug wires and get the left side to fire off the right side coil/wire/cap. Then I switch back and the left side fire off of the left side coil/wire/cap. I switch only the coil wires and nothing fires. I switch only the condenser wire and still only left side fires. So to me it seems like coils wires and caps are ok. Now I'm wondering if the no spark issue is somewhere between the condensers and the points? And I still can't get the right side to fire at all even when I switch things around so there is spark on that side. Thanks for all your help and patience with me! It's nice to have some direction.
 
Well yes, it could be the right side (top) points set. The gap may have closed up due to wear or the points surfaces may be contaminated with oil or something. Have a look. Check the gap and clean the points. Also check the wire from that points set. Sometimes they break internally along their run somewhere. Test that length of wire for continuity.
 
Well after cleaning up the points and some connections I am getting spark on both sides! I also noticed one of my plugs was putting out a much weaker spark than the other so I just put two new ones in. So once again I am back to where I started. I am getting both sides to fire but the right hand side is rough, misses, pops, smokes when I crank the throttle from zero to full real fast and the pipe on that side is much cooler than the left. I also kind of notice a weird clicking or clanking noise when I listen closely at the end of the tail pipe as opposed to the left side. Any ideas?
 
I am also noticing that at idle it's not really firing much at all on the right side and the pipe stays cool. However when I work the throttle it fires and smokes and warms up. I think maybe the clicking noise I am hearing is the vales and piston and what not just more easily heard because of not really firing at idle, because once I give it gas and it fires I don't really hear it.
 
Since you are now getting spark on both sides but still having issues with not firing on the right side at idle but under throttle it will fire and run on the right side you may want to look at the pilot circuit of the right hand carb. Also you should put a timing light on each side and make sure that both sets of points are firing at the right time as their timings are set individually.
 
I am going to tear into that right side carb today, just not really sure what I should be looking for? As far as a timimg light is that something a local auto parts store would carry or will I need to order the one on mikes xs?
 
Your local auto parts store should have timing lights, they may even have one on a loaner tool program. Before tearing into the carbs make sure to read the info posted in the tech section about carbs so you have a basic understanding of how these carbs work and what parts are what. There is a wealth of info in the tech section.
 

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