Very weak spark on a 93 Zr 1100

[ujmman]

I need help on a spark issue on a 1993 Zr 1100. Carbs where cleaned properly and bike taken on a 50 mile ride. Good performance up to 90 mph. Above that sluggish and missing. A few days later would not start and the occasional loud backfire. The amount of spark was not enough to start the engine. Switched a working igniter from another bike, no change. Any suggestions would be appreciated.

Thank you

[Richard]

Well as my own bike did start on 2 cylinders easy (in the past before maintenance etc) I would first suspect the battery as it needs a decent amount of voltage for a bright spark. What does your head light do when starting (does it become less bright much) and can you start the engine for a few seconds or not?

[hugojose]

Have you checked the voltage the bike makes?? It should be well above 14 VDC when you rev it

Regulator/rectifier is another consideration, as igniter has to make do with the voltage it produces

This may not be your problem, but I'd mention something I encountered once;

Mine is a 91 Zephyr 750; (27 year old). After determining DC voltage would remain below 14 VDC, reving, I found low voltage from the Alternator due to the connector getting corroded; heat had melted the plastic separation between two of the phases, only air was between. Had to make a new connector for it.

The Alternator has three phases, AC (Alternating Current, not DC) before the rectifier/reg. It could be tested by disconnecting, starting bike with a good battery, and preferably helped by battery pack. And voltage between phases a 4,000 rpm should be above 31 VAC (this is on the Zephyr 750). Don't know if the 1100 uses same alternator.

[Richard]

I second this whole story. Had exactly the same issue as I will show later elsewhere on the forum.

[vambo]

You could start with testing the ohm in the plug wires/caps.
They do get a lot higher ohms with age and need to be replaced.
Did that on my 550 and it started on all 4 once I hit the button.....

Leif