Hey guys I need some help fast. I have a motorcycle safety course on Thursday and my 91 FXLR will only fire on the front cylinder for about 15sec after start, then it only fires on the rear alone. I have spark, and fuel. Rear cylinder is fine. Ive swapped Coils with a buddy, switched the wires around, and changed wires and plug. Im lost please help.

 

Did you try a new plug?

 

Stock or aftermarket ignition?

 

What happened when you did all the above?

 

Was wondering is it carb or EFI?

 

A couple times.

 

Stock HD ignition.
It still wouldn't fire on the front cylinder. Id keep the bike running and disconnect the front plug wire and idle would not change. disconnect the rear and obviously the bike would die.
Carb

 

What happened when you switched wires.
(on the coil switch the wire positions)


This is a dual fire coil right?

 

Yes its dual fire. The rear cylinder continued to fire off the front coil wire and the rear coil wire would not fire the front cylinder

 

kind of odd it only runs 15 seconds,It might make you think of a intake leak but not quite the right feel for that with the long range description.When it does run does it run strong or is it weak????



you dont have stainless wrapped plug wires do you??




next thing is a leak down test might be a good idea------------just to rule out issues and to work backwards.When you are short on fuel you can sometimes get enough air and fuel to mist one cyl but not 2 .my old shovel would only run on the back cyl when it ran out of fuel but it would run 5 miles like that.No one could explain that and lots gave theories