[BoVL800]

A few weeks ago it was 60 degrees in SE Michigan and my 2004 VL800 rode perfect. Its running a pod filter and has been rejetted for years now without issue. A week later it was 40 out and she was sluggish as hell, didnt want to go and wouldnt rev very high. I thought maybe it was too cold for her as my commute is only 15 minutes. I had to have the "choke" out the whole ride and when i shut off the bike it would bike fire something fierce. Today was 50 out so I was going to fire it up and see if it would run better. However, it wont start at all now. Cranks over strong but wont start. It sounds like its blowing air back through the carb during cranking. I pulled the carb and cleaned all the jets and passageways then reinstalled everything but it still does the same thing: cranking, blowback through carb, no start.

What typically causes air to blowback through the carb? Timing? valve adjustment? Trying to get an idea of where to look first.

 

[Psyc0]

Sounds as if a valve face/valve seat have badly burned due to a lean condition.
Pull the spark plugs and compression test both cylinders.

 

[BoVL800]

Thank you for your response!

I went to local auto parts getting place and rented a compression tester. Well go figure it didnt fit and the "adapter" wasnt really an adapter. Anyways, i had the plug out so i figured i would test them. The forward plug wasnt sparking at all. I swapped it to rear position and it wouldnt spark there either. The rear plug sparked in both positions just fine. Installed new plugs and she rides like a champ just like before.

I have worked on many different vehicles of all makes and models. I have never had a spark plug straight up fail like this before. First time for everything I suppose.

 

[Whiskey]

At least it was a cheap and easy fix. Thanks for the update.