new and need some help

[gsxrkneedragger]

ok, so i'm new to this forum first of all. i have a 03 lt-z400 that i just got recently. i don't know much about them, but i play around until i figure it out. my problem is...when it is idling, or when i rev it in neutral and putting around the yard, the bike works fine. but as soon as i give it more gas it seems like it misses. i pulled the plug out and replaced it figuring that was it, but it still does it? would it be a dirty main jet or something like that? anyone want to help me out so i can get back to riding? thanks in advance

[GPracer2500]

Is it stock? Has it done that since you've owned it or is this something new?

Regardless of the answers to those questions the first thing I'd do is remove the carb and clean it. Clean carbs solve lots of running issues. I always use carb cleaner and compressed air. There are some really small passages within the carb so a combination of compressed air, carb cleaner, and disassembly (as needed--at least remove all jets) is the surest way to eliminate a dirty carb as the problem. Once you're sure it's totally clean (internally) you can move on to other, perhaps less likely, causes.

If it's not simply a dirty carb, it may be jetted incorrectly. One troubleshooting idea that could reveal poor jetting as the issue is to remove (or install) the airbox lid. In effect, you're changing the jetting by doing that. If the issue disappears with the lid off you know the problem is too rich jetting for running with the lid on. Another trick is to barely engage the choke to artificially and temporarily richen the mixture. That works better on some carbs than others but it could help you determine if the problem is related to being too lean or too rich.

If it has nothing at all to do with the fueling (which I kinda doubt) then....well, you can cross that bridge when you get there. Excluding the carb (just dirty or maybe miss-jetted) would be at the top of my troubleshooting list though.

$0.02



BTW, the only reason I opened this thread is because of your screen name. Getting a knee down is one of the best things in motorcycling, IMO. :devil:

[gsxrkneedragger]

yeah it is stock except for a k & n. it just started the other day after i was riding in a muddy field. i'm gonna go take the carb apart now and see what that does. thanks for your help.

dragging knee was the biggest rush when i rode. until that one day....

[Off-Road Maniac]

My first thought was jetting. But if it just started doing this maybe dirty air filter or you have crud in your carb....