All right heres the deal, I just bought a used 2004 Sportsman 90 for my son's birthday. It runs great but you have to hold your thumb on the throttle or it will kill. This is a problem because he is young, and I have the throttle regulator screw in place so he can only go about 10mph.. Every time he removes his thumb it kills. The bike had been sitting for about 6 months in the desert heat so I drained the fuel and have replaced it. It runs so well other than idleing. Can I just turn that thumb screw on the front of the mikuni vm 16? Do I need to adjust the cable length at the carb? Do I need to mess with the contacts in the casing up by the thumb throttle? Which is correct?

Thank you! I am new to this two stroke business!

 

I have been told by a friend to remove the top of the carburator, and clean out the jets with a pipe cleaner. Is this necessary?

 

have you adjusted the idle screw

 

Give the carb a really good cleaning (complete disassembly) inspect all parts, if it still doesn't idle adj. the idle screw if it still doesn't want to idle I would have to say you have a bad crank seal I've seen this a couple of times now may not sound right but we havehad to replace 2 seals in the last 2 months.

 

I adjusted the idle screw and it works great. I found a website that had the Mikuni vm 16 carb diagram. Thank you!

 

Have you tried adjusting the cable at the handle bar ?