I have an 03 400, and was wondering if anyone can tell the current size jets in it. I'm looking at a jet kit, as it feels like it's a little sluggish. I tried using a little choke when I was riding, and it seemed to wake up a little bit, so i think I may be running a little lean. Any help is appreciated

 

Are you aware that the jet by itself only controls fuel at or near WOT, so if you were not tunning flat out a jet change may make things worse. Rather than start buying jets, why not try checking the float level and raise it if it is low (or even if it isn't because a high float setting will enrichen the system. While in the carb, raise the needle in the slide one notch. Both do the same thing and cost nothing. Have you checked your spark plug to see what condition it is in (a worn plug will make an engine act like it is lean)and how lean your motor really is running?

 

I'm aware of the main jet controlling the upper third of the throttle, I guess I could have been clearer, looking for more of the best combination. The bike has only got 1450 miles on it, so I would think the plug would still have a little more life in it yet. Guess it couldn't hurt to check it though. I've never touched the carb, or tweaked any settings other than the idle speed. if possible, I'd like to adjust it externally first, before tearing it apart. If i set the needle one setting lower, it should richen it up a little, correct? I'd rather run a little rich than lean. I am going to pull the plug and have a look. I get a backfire once in a while while decelerating, but it's intermittant.

 

Owners manual says 4000 miles or 18 months. Having been in the engine maintenance business on marine engines (average 37 hours a year) change the cheap stupid thing every year and save yourself some grief.

 

buy genuine mikuni main jets at www.jetsrus.com. get a choke conversion kit there too...makes rejetting easy.

 

A Mikuni jet kit? The bike has a Keihin carb, didn't know the jets were interchangeable. Why would I need a choke conversion? I'll stick with the one i've got, I know it works good. They sell alternate jets from the factory, but I don't think the main jet is what I'm looking for, I want low-midrange performance , so I'm thinking of moving the needle up a notch and maybe changing the pilot jet to a bigger size.

 

oops...I thought you had a DVX 400. MY mistake. They do have keihin main and pilots too, i got some for my rincon. Sorry about the mistake!