Z1100 firing on three

[doebag]

So for the first time in absolute ages, the Z1100 let me down.
Started on choke as it always does, top of my road choke fully in and running well. Four miles later it was definitley not happy, pulled over and it cut out, tried to restart didn't want to play.

Long story short, AA got me restarted, cyliner 2 is not firing [cold header pipe, other three too hot to touch] Remove plug cap and no spark when held to cylinder head.

Is it possible for a double coil to fail only on one cylinder ?
Any other possibilities except HT lead.

[warren3200gt]

Yes it is possible for twin coil to fail in one side only. The wires inside have to split into a Y to to the two ht leads. I seen it a couple of times on hard wired coils where the ht lead can't be replaced (easily).
Your coils have changeable ht leads. It could just be the dead ht lead wasn't pushed right onto the internal coil prong and has just built up carbon through arcing to the ht lead.
I would remove that ht lead and trim it back by 10mm and try to clean the coil internal prong. Then refit the ht lead ensuring you push it right in before tightening the plastic lock knurled thingy what ever it's called.
If one side is working it's likely the other is also.
Coils tend to fail though over heating melting the the insulation between the windings so both sides would die.
Assume you've checked plug and plug cap are good especially cap to lead joint is tight and clean. Again trimming the ht to clean core before refitting.

[KevH]

That's very interesting, I didn't realise that the twin coils could fail on one side. You learn something new every day. Thanks.

[doebag]

Thanks for the reply, I checked the coil using the info in the workshop manual and it checked out OK.
Cut back the HT leads by about 10mm and it fired up and ran on all four.
I think I killed the battery when she cut out as it would not restart when I turned it off.

New Motobatt on order from Wemoto

[warren3200gt]

Why are you buying a battery from Japan.
Tayna.co.uk is the go to UK supplier for motobatt. 1 or 2 day delivery time.

https://www.tayna.co.uk/car-batteries/? ... hKEALw_wcB

[zed1015]

Why are you buying a battery from Japan

Wemoto is a bike shop in Brighton..

[warren3200gt]

Wemoto doh, webike.

[doebag]

Just to finish off then, I started the bike on the old battery and took it out for a ride and petrol, when I got back the resting voltage of the battery was only 12.7v. So not dead but not the best. Not sure what the cranking voltage was but it sounded much better when boosted from my car.
New battery fitted, sounding much happier.

[warren3200gt]

If the old battery was also a gel battery when they get drained below a certain point you can recharge to show good volts but often they can no longer supply the amps required.