I have a 08 nightster that began making a rattling noise. I changed the oil with Harley 20/50 and oil filter. Days later after the oil change i noticed the bike started making this rattling noise. The gas smell is extreme now from the exhaust. I punch the throttle and it still goes but sputters and rattles. I thought it was bad gas, so I emptied it out and put new gas but still does the same. I have checked the oil and its fine. Does anyone know or have heard of this problem? Any help will be greatly appreciated!

 

I am by no means up on the nightster engine, but maybe this thread that I just happened to run across will shed some light on your issue.

https://www.hdforums.com/forum/sport...od-rocker.html