running weird
 

i have a 2008 UM 250xspeed (Hyosung MS3 250) i cannot for the life of me figure out what is wrong with it. it will stall for no reason. but only when i come to a stop. not all the time. it seems to idle low. i went through it as far as my experience let me. i changed the oil (Amsoil 10w-40) changed the air filter, cleaned the MAF, put in a new spark plug (an irriduim this time) i'm about to throw in the towel. i joined this forum to see if anyone might know what could be wrong with it. thanks.

I'll try to help if I can. I guess my first question is whether it is carburated or fuel injected. I know nothing about EFI engines.
If it has a carb, does it cold start easily? Does it have a fairly high idle speed while cold? If so, does it start fine then develop idle problems as it warms up? If all of these apply, focus on the enricher which is the "choke" mechanism on most of our scoots. I will share what I have learned if these issues apply to your bike. Standing by for your reply

no. it's FI & liq cooled. since i put the plug, it starts much easier. there is a motorcycle shop nearby. they will work on it $85/hr though. i'm not working so that option is on the back burner until i get work. i feel it's dependable to ride for nearby errands. but long trips i'll refrain from.

I found a fourm for that brand,
http://korider.com/index.php?PHPSESS...bd3&board=18.0
maybe digging in there could help you.
Good luck man.

have you adjusted the valve clearances recently?

no. i haven't. i don't have internals experience. just basic maintanance.

Initial valve clearance should be checked at 1000km, and every 4000km after. Your system uses shims, which makes it a bit more of a hassle to adjust. Here is a link to the MS3 250 service manual. http://files.hyosungmotorsusa.com/MS...ice_Manual.pdf
If you have more than 1500mi on your scooter, this could be part of the problem. Having never adjusted a shim valve set, I can't be much more help, sorry.. but hopefully someone with experience on this particular scooter will jump in..