...not on every cold startup but on a few. It always run after the pop. Never popped and died. Never popped on warm or hot startups. 09 FXDF, Stage II 103", Bub Lakester with HD HB. Never happened before the Stage II. Was in Stage I a while, started fine. No popping then.

From other threads, I guess it's the fuel in the exhaust from one cylinder not firing at the first turn being combusted by the exhaust from the other cylinder that fired up on the same turn.

If so, does this mean that the cranking fuel (or even AFR) is too rich (at that given temperature) or too lean? Or is it some other problem entirely.

Would adjusting the cranking fuel program (either raising or lowering the fuel amount) in the ECM solve the problem? It is annoying and embarassing. I hate to scare old ladies in the early mornings.

Thanks a bundle in advance!

 

Too lean.

 

The stage II ECU download needs adjustment or you have a leaking injector. Not likely an injector but it has happened and upon warming up the injector seals back up.
Is it by chance the rear cylinder?
One other thing, the timing may be part of the problem. If the spark is advanced too far in the idle / MAP areas, it may not even ignite the flame front because no cylinder pressure has developed yet, in the cold cylinders.

 

I would do 2 things.

1. Clean your fuel injectors with some techron or redline SI1 in the gas. Also check the wire connections to them.

2. If you have a sert or tuner where you can adjust the enrichment/rpm steps for temperature then I would make them a bit leaner on the colder temps and see if that helps.

If this is the first time you have had this build in the cold weather I would suspect the tune. If the bike has been in the cold before and this didn't happen then I would suspect the injectors.