Lost 2 sparks?? Where could they be

Hi so first of all I would like to apologise for not being able to find the section to introduce myself. Hopefully I will be able to find it when I look on the laptop instead of the phone so apologies for that.

I'm having a head scratch of a problem with my xj600 diversion (in the UK) the bike is a 1992 and has only 15k on the clock and by any standard is a good 9 out of 10.

Has been sat for a few years and didn't run so carbs off cleaned and balanced and it fired into life on the choke....great! But quickly realised cylinder 2 and 3 had no spark. Seeing they where on the same coil and that the coil had 12v and a good earth I suspected a dead coil. All was in tolerance but ordered an pair of good used ones on eBay but still no spark on 2 and 3.

Next step check wiring. So I checked continuity between coil live feed and main fuse (ino it has power but check twice to eliminate) all was good. Continuity from the grey wire to cdi unit, all good. Solo abit puzzled I removed the engine cover to reveal the pick up and all looked OK. Thats where my knowledge ends. Im not 100% but I'd say being only one pickup that if the coil for 1 and 4 is firing then the pick up is good? (Only one pickup) checked resistance and from what I can tell its in spec ( checked resistance on the 2 wires coming from pick up)

And thats it I'm puzzled I do have a second hand cdi coming off eBay but I'm unsure if its this and any help would be massively appreciated. I have a good knowledge of motorcycle mechanics and undertake it all myself so can test or check anything you guys suggest.

Only other thing I need to ask is after looking at the wiring diagram surely a faulty cut out switch would cut both coils??

Thanks in advance and can't wait to hear from you all

 

Forgot to add battery is new holding a good 12v. Changed plug wires and caps and coils.

 

I have no experience with anything close to your bike, but I think I would be checking out the pick up coils. Assuming there's 2 like the older xj's. Not sure where to direct you for proper wire colors, or what reading(s) you should expect unfortunately but hopefully someone much more knowledgeable than myself will be along to guide you

 

Try to start her in the dark. Old plug wires can crack, and then the sparks stop going where they're supposed to go.
If you see a light show, replace the plug wires.

 

look where you did work ohm out plug wires with caps in place maybe no connection

 

Will double check plug wires and caps tonight and let you all no how I get on. Honestly am puzzled

 

So had a few hours off work this morning as a job cancelled so went and checked caps and ht leads and all seem OK. So then took a ht lead off cylinder 4 (one of the 2 that where working) and put it on the other coil and still no spark. Its like the coil is dead but I no it can't be as have tried 3. Properly stumped so looks like I'm waiting till the second hand cdi turns up

 

Forgot to mention continuity tested all other wires all could find and all seem OK including connections. I did notice when running on the 2 cylinders the tachometer didn't work and seemingly this is linked to the grey wire on the coil that isn't firing. Has as good connection between cdi and coil so I'm leaning towards the cdi still

 

Did you ohm between the 2&3 coil wires to check the secondary side?

 

Just followed a guide on a website tested between the 2 terminals on the coil and between the 2 ht leads. Electrics is by far my weakest point to be honest. Mechanical is far easier in my view

 

I thought my coils were bad, but it ended up being just the caps. These guys helped me a lot.

 

Welcome ...try this next ...move one of the "dead" cylinders plug to one of the "live" cylinders and see if this follows unless you already tried it ...I have had spark plugs go bad before.

 

One other thing 82 Honda CB 750 coils are a direct replacement for the coils , These are Hitachi coils and have replaceable pug wires and can still be bought new ...but I cannot say that it is different on the European model.

 

I'll go in the shed tonight and hopefully take some pictures and test moving a cap. Never thought of that. The caps seem good but I could be wrong as I have been many times before

 

OK so I've had some shed time and time to update. Basic test put coil 1(working one) wires onto coil 2 (no spark coil) and coil sparked so its definitely not the coil plugs or leads and caps. Tested pick up again all looks good. Checked voltage at coils. Over 12v on the shared live feed. Now the other wire from the cdi

Coil 1 (good coil)
Orange 0volts
Hit start button
0v to 0.4v fluctuating
Probably in line with spark

Coil 2 (no spark)
Grey 0v
Hit start button
0v to 12v and stays at 12v for a few seconds after button is released
In line with spark

Me being an idiot ordered a 4br 10 CDi instead of a 4br 00. So have to wait for another one to arrive

Should I be looking at anything else.

 

Have you tried new spark plugs yet?

 

Yes have 5 new plugs (1 spare to test with) all 5 spark on good coil. None spaark on the bad caps