Well one thing could be causing both the smell and the knock.
If it isn't fueling correctly it will cause a knock and a bad smell.
I'm from the old school, used to ride a KZ900 in the '70's.
If the carbs were out of sync it would knock because one cylinder was trying to outrun the others and it would make the crank knock.
It would only do it at an idle and at low RPMs, once fast enough the knock would go away.
If one of your injectors is bad or dirty it will have the same symptoms.
My old Scoot
I used to pick the front wheel up in first gear and not set it back down until it was strung out in 5th gear as fast as it would go.
I was an adrenaline junky then.
Sometimes my memories scare me. :shock:
KomaToast
