'03 Honda Sporttrax 400EX Carb issue.

[Dumass]

My name says it all. I have a '03 Honda Sporttrax 400EX with a new aftermarket carb on it that seems to be having issues. I can start it but it idles really rough and when I give it throttle it just kills the engine. I have tried adjusting the idle screw but to no avail. I am in the San Diego Ca area. 

Any advice will be greatly appreciated. I would also like to get an owners manual for the thing too but can't seem to find a downloadable one.

[Gwbarm]

I have also had some of the same problems with aftermarket carbs, try adjusting the mixture screw located underneath the front of the carb, also check to make sure your throttle plate is closing all the way at idle, you may have to adjust the cable. if that doesent help compare the jetting with the original carb. If you still have the original carb clean it good and put it back on.

[Mech]

Yup, what he says.. But.. what do you mean by "to no avail", ? Did the engine respond to the mixture adjustment ? Could you get it to go too rich, and too lean ?

Does the idle speed respond to it's screw being turned ?

And I'd just clean and check the original carb if it's the genuine one for the bike. The aftermarkets can need a bit of tuning.

[wwsivicww]

intake leak check the intake boot between the carb and the head, check that seal

[Mech]

Yeah could be that Ww. If the carb's just been off then, yup, the rubber could be split. Good idea.

Most of the time though, bad vacuum effects the idle more than it does an engine at revs. If they will start and idle, (even with a vacuum leak), then they will generally rev up and run pretty much as normal. There are exceptions though, such as the carb moving in the rubber, or the rubber flexing and letting air in.