Fine Tuning

[Duke400ex]

Hello Everyone. I have been trying to "Fine Tune" by 400ex so I installed a 42 pilot jet and have been playing with the fuel mixture screw in different places but now when the bike it at idle every once in a while it makes a "hiccup" sound. It is coming from the air box when it happens. The bike still runs good just am trying to figure out what that might be.

ALSO, does anyone have for sale or know where you can buy a aftermarket fuel mixture screw. That little D screw is a pain in the butt to turn without proper tools that is.

[madmaxmodquad]

that hiccup most likely low vaccumm from needing a valve adjustment

[hocman123]

u can order a rebuild kit from ebay just search for 01-04 carb rebuild and it will have the sloted screw head one in it. also the kits that come with new needles and seals and a few other things cost just about the same if not less the just ordering a new screw from honda by itself

[Duke400ex]

Ya the slotted screw would be much nicer but I was hoping that I would be able to find something like all the ones they make for FCR carbs so you can just turn the dial.

I don't think that it is going to be because of the valves needing adjusting though because they were just adjusted a week ago. But I guess it could be.

Anyone else have any ideas?

[chevymanrick]

Mine does the exact sane thing, it runs fine, but just hiccups every couple seconds when its idling a lot of people have said to check your headers make sure they are tight and not leaking air

[Duke400ex]

I just recently had those off and they were torqued back down to what LRD gave in the instructions. I was thinking about putting the air box lid back on to see if it is maybe getting too much air.

[russellsroost31]

mine does it when shes warmin up but after i get here all nice and warm it soesnt do it any more