I let my bike warm up for about 20 minutes, shut it off, had dinner, came back and it barely runs now. Any ideas why?

 

Probably can't help your issue: just curious WHY you let it warm up for 20 minutes ? And was it idling that whole time ? On my old bike, even in the colder months, it doesn't take 20 minutes to warm up. That said, on my bike, I'd be pulling the plugs for a look.

 

Don't know for sure why it's running so bad but I do know that after idling for 20 minutes without any air flow it got a WHOLE lot more than warm. Burnt toast is the first thing that comes to my mind...........

 

If it does run take it for a gentle ride round the block to give it some fresh air. If it seems reasonably OK don't stop, just carry on for half an hour, so it warms through properly. Stop starting and stopping the poor thing!

 

What he said. I wouldn't let my bike idle for 2 minutes, let alone 20.

 

Good call on pulling the plugs. I suppose I should be checking for the gap? Um, and replacing plugs is never a bad thing anyhow.

Why do I let it warm up for 20 minutes? Because if I don't, the bike backfires and misfires like crazy.

Yea. The problem is if I don't let it warm up... it runs horrible.

 

if it's carburated, I would check the jetting. If it's not jetted correctly it'll give you the problems that you are descripting

 

Got it. I'll give that a shot too. Thank you.

 

Jetting sounds like the problem, I would also go ahead and check your intake manifold gaskets for leaks.