Misfire - Z1B

[kawasaki_man]

I've been struggling with an intermittent misfire on my Z1B for a few weeks now and I thought I would share my findings just in case other Z1 owners have been suffering the same problem.

Bike always started up OK but after a little while (say 4 miles) would suffer from an intermittent misfire and lose all power. Sometimes this would clear and then run OK for a few miles then misfire again.

Thinking it was being caused by poor fuel from last year I went and filled up a fresh tank, same misfire problem after a few miles.

1. Checked fuel supply, seemed OK, 2 in line filters are fitted so could view fuel flow when bike was running.

2. Checked the 12 V supply from battery to primary windings. Found 0.5V drop. Checked all connectors, found minor problem with 4 pin connector under tank that goes to and from ignition switch. Clean up connectors and voltage drop now only 0.1V.

3. Bike was outside in the sun, tank taken off. Checked the resistance on the coil primary windings, right hand coil 3 ohms, left hand coil 6 ohms. Decided to clean the connection to try to improve reading for left hand coil. When I re-checked the reading it was now open circuit. I decided to replace the coil with an old spare I had. When the original coil was taken off and put in the garage, I subsequently decided to check the resistance for the coil again, it now read 6 ohms. Later that evening I placed the coil on a radiator and noticed that within 2 minutes of warming up the resistance had gone to open circuit.

In summary, if you are experiencing a mystery misfire problem might be worth checking that resistance of both coils is close to 3 ohms. Also try gently warming the coil to see if it goes open circuit when heated up.

I hope this can be of some help to others. It certainly has made my day knowing I can ride the bike again without fear of the dreaded misfire returning to ruining a nice day out!

[Mark Tiller]

Thanks for posting, always good to know when a cure is found

[Jay1969]

Nice one kawasaki_man glad you got it sorted