1976 XS650-C Project From Ireland

Did you measure through the plug cap or just on the plug wire? If using 5K ohm caps, that would be added to the 8K ohm coil value for a total of around 13K. Yes, it should spark with that. The original caps were rated at an oddball 8 or 9K ohms so the total with them would be even higher, and the bikes ran.

Are you sure that aftermarket ignition is wired in correctly?
 
Ok that makes sense, I measured it through the plug caps and they’re 5k plug caps so that 13k value is spot on.

It must be the ignition unit so??
 
Could be, or the unit may be wired incorrectly. I thought you had pics of the coil connections and I thought something looked off. I thought I saw orange and grey leads connected together in one spot.
 
Hi @beano

Welcome to the forum.

I see you had the coils off and cleaned up the contacts and you've also tested them with a multimeter. In theory they are good. But have you tried bench testing them? By this I mean running a couple of wires direct from the battery and then making and breaking the connection. (Make sure the spark plug is earthed against the fins).

We don't know if the electronic ignition is still good and is wired up correctly, but all any ignition system does is break the power to the coils at the appropriate time. You can mimic this action with a couple of pieces of wire.

Dave
 
Could be, or the unit may be wired incorrectly. I thought you had pics of the coil connections and I thought something looked off. I thought I saw orange and grey leads connected together in one spot.

Yes I have removed some pictures and edited some earlier posts because they were getting quite muddled and after re-reading them I realised that I needed to be a bit more concise.

I have the coils wired up as follows, please note photo was taken from the LHS with the RHS coil in my hand.

S0H87Rfl.jpg


There is an orange wire connecting from one coil into the grey wire to the ignition unit, now I may very well be wrong but this seems to correlate to the wiring diagram supplied with the ignition unit..................which itself may very well be wrong.

JzkXMoel.jpg


Edit: I have also come across this link which seems to indicate a problem with the supplied wiring diagram.

http://www.xs650.org.au/Technical Info/Ignition.htm
 
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Your coil wiring looks correct. Even though many of the stock wiring diagrams show a gray wire coming out of one coil, orange wire coming out of the other, I've only seen these stock coils with orange wires on them. That Australian web page is rather vague, not to mention the terrible, blurry pics, lol. I'd feel stupid even posting a pic that bad. I guess the only way you could find out what he actually did would be to contact him. But good luck with that, the posting is very old I think.

I think the wiring diagram you have looks correct. I don't see what could be done differently. I'd run those simple coil tests DaveO outlined.
 
I think the statement "Again I found faults. The wiring diagram is incorrect and I had to swap over the coil wiring, to make the bike run." from xs650.org.au is maybe a bit of a read herring." Perhaps he hadn't labelled the coils "RHS" and "LHS" as you have. (Does it even matter? I don't know.)

If its any help with orange wire / grey wire conundrum when I took my standard stuff off moons ago to fit a Boyer I wasn't very confident with my electrical skills (not much has changed) so I made a diagram in case I wanted to put it all back. If its any help here it is.

IMG_2144.JPG

It shows both coils having brown (power) and orange (back to the points). One goes via a red and wire one via a grey wire. I think your wiring is might be OK but we can't see all of it. You said you'd heard it running. But there's something funky going on here …

funky.JPG


Maybe a short?

I'd bench test the coils. If you can get a spark out of them. I bet you can. You'll have eliminated half of the system as being the source of the problem. Then we can start back on the Newtronics stuff.

I bet their documentation is right .. but its not very clear I must admit.
 
I think their wiring diagram is much clearer than that Aussie site's info, lol.
 
Thank you so much for all your efforts @DaveO @5twins @MaxPete I have good news to report........we have spark!!

I was feeling pretty confident about the coils after the results of the testing earlier so turned my attention to the wiring on the Newtronic.

After a few minutes of staring at things I wasn’t very happy with the way the ground wire from the ignition unit was earthed (to the top of the airbox).

So I unscrewed it and attached it to the negative from the battery and voila, plenty of glorious beautiful sparks.

Once again thanks to all for the great advice above, it really sped up the process, just need to pull the carbs now and give them a quick run through.

Hoping to hear her run tomorrow, fingers crossed that the carbs don't hold any nasty surprises.
 
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On the original harness, that is a very important ground wire. It doesn't have anything to do with the coils really but it is the main ground wire and ground connection for practically everything else in the harness that needs a ground. I moved mine over to the right coil mount because I needed that left side for my Pamco ground.

MO1e2Qs.jpg
 
Yeah, the airbox wouldn’t be very good because for one thing, it is all painted and that paint is an insulator plus, it is at least partially attached to the battery box which is suspended on those four big diameter rubber isolators that keep the battery from being shaken to death.

Anyhow, as 5Twins stated - ground (aka earth) connections are very important and as several other people around here have pointed out before - “these bikes vibrate a bit you know”. ;)
 
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Update Time:

I removed the carbs to give them a clean etc, they were pretty dirty and gummed up.

DVamsx1l.jpg


the main jet was butchered but with a bit of patience and some heat and penetrating fluid I managed to get it out and replaced with a new one.

WsYDOxcl.jpg


FcieEKKl.jpg


It took a couple of hours but I managed to get them pretty clean in the end, its amazing what you can do with a can of of carb cleaner, a toothbrush and some compressed air!!

v0hLD8Vl.jpg


Then I set the mixture screws and the the float heights to spec and re mounted them, all good to go.

It was finally time to see if she would fire, so I switched on the ignition and gave her a kick and the thing damn nearly broke my ankle, a second attempt confirmed the first, and after limping back inside the house I did a few searches on here, and came to the conclusion it must have something to do with the advance mechanism.

After ensuring that my ankle was in fact not broken I swapped over the plug leads to see if I possibly had wired the coils backwards but while there was now no kickback there was only some small backfires.

So that's where we are as of now, I'm thinking maybe pull the rotor from the advance mechanism and start again?? must find that timing light..............
 
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Check the advance unit and advance rod running through the cam. They get all crusty and rusty then don't function as they should. Both need to be kept clean and lubed up. A quick test is to rotate the advance rod by hand on the advance side, until the weights spread out, then release. It should snap the weights back in smartly.
 
Well, you’re making progress at least Beano. I like that wooden box you are using for the carb parts!Pete


Thanks Pete, I made it originally for my fzr carbs which have different jets, needles and other random components that are specific to each carb, so keeping everything organized is important. It is very handy to have when you have them all stripped and are waiting a few weeks for parts, makes it much easier to remember where everything goes!!

Its a bit overkill for the xs carbs as they're quite simple in comparison, but I have it so might as well use it.

qnluFWRl.jpg



Check the advance unit and advance rod running through the cam. They get all crusty and rusty then don't function as they should. Both need to be kept clean and lubed up. A quick test is to rotate the advance rod by hand on the advance side, until the weights spread out, then release. It should snap the weights back in smartly.

Thanks for the suggestion, I will check all that and pull the advance rod some evening this week. I have never worked on a bike with an advance mechanism before so will do some more reading up before I go at it. I need to step away from it for a day or two anyway before it drives me insane!!
 
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Beano, great photos of the bike! I would never have imagined just how much a bike can change with time. Did your Father own this from new? Good move getting a new harness. By the time you mess with and clean up an old harness you end up wishing you had bought a new one. The only issue is that sometimes the new harness has some little variations that can get frustrating to sort. But all your connectors will be shiny, new and trouble free..
 
Yes, the advance unit and advance rod are two of the most neglected items on these bikes. They were lubed up when the factory assembled them many years ago and most have never been touched since, lol. Even though none of the manuals mention them, keeping them lubed should be considered a maintenance item. It doesn't need doing often, maybe every couple of years, but it does need doing.
 
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