Wrong cylinder firing

[DarrenB250]

Evening guys... Got an XS250 that wont fire, all wiring seems correct to the coils.. but just put a timing light on it the left HT lead, and checked in timing window and RF wad better highlighted. Rechecked wiring and all seems correct..any one experienced this before?

 

[CaptChrome]

My thinking is that either the coils are wired backwards or the cam is not timed correctly.

Have you ever seen this bike run in the past?

 

[Guitarguy1996]

Agreed. If your plug wires are long enough, you can just run them to the opposite sides just as an easy way to test it out. No shame in it, I've gotten them backwards many times. Also, cam timing could be off by quite a bit. Or at worst you could have a shredded woodruff key in the fly wheel but hopefully it doesn't come to that... I'd flip them and give it a try.

 

[drewpy]

you can actually run these engines backwards if the ignition timing is wrong. electronic ignition helps to prevent this.
You need to start from the beginning, check cams, your on actual TDC firing and then ignition test using a dwell meter.
leads are easy to swap around too