zachap wrote on 05/06/12 at 06:34:41:I am the new owner of a 2007 S40. The bike idles great and seems to do fine under hard acceleration. The problem is that when riding at a consistent speed (partial throttle), the bike sputters and jerks. It runs better with the choke on. I have run it for quite a while to make sure it's good and warmed up the it makes no difference. I have changed the plug, checked for vacuum leaks, checked and cleaned the air filter and this week I pulled the carb apart and gave it a good cleaning. No change... The bike has 7,500 miles on it. Any ideas??
Thanks in advance
After reading all the replies, here are my thoughts:
You don't seem to be a NOOB as someone suggested.
What kind of gas are you putting in? Try to run E free if you can. If you can't, run 91 or better. You'd be surprised in the difference.
I think you may need to clean your main jet again. I would spend the 3 bucks on a new one.
I would think it's a pretty simple issue, and maybe when you cleaned the carb you missed a little in the jets.
I can't imagine that you need to add spacers or a different spring or stand on your head while starting.......