Does this Sound Right

[Blackguywithouta400]

I recently got a new 02 400 and quickly added a K&N filter Outerwear’s pre filter, and Outerwear’s cover on the air box with the lid pretty much cut out to the fullest. After this mod the bike had a really bad stumble off idle and no top end. So I rejected it to a 150 Main, and lowered the needle 1 clip, it runs really well at my home but when its hot out I don’t have any low end just top end, my bike has the stock exhaust on it for now but ill soon replace it with a Duncan Racing system when get the extra $ The pilot jet is stock and so is the adjustment on it. Also im in Seattle pretty close to sea level. I just want to know if I can go any bigger or make any more changes with the stock exhaust or am I just maxed out to what I can get in right now. My goal is to have some stronger mid to low range as I ride in the trails most. All advice would be greatly appreciated.

Check this link out: http://home.earthlink.net/~gellett/silencer.htm

That is some mods you can do to the stock silencer. Other than that, the only thing I can think of is your just running to lean. How does the spark plug look? If you have access to a stock lid with no holes try running with that and see how it does. Might just be sucking a lot more air than it needs right now, (till you get aftermarket exhaust). I run in AZ with no lid, a UNI, and an outerwear with the Pro-Circuit pipe and my jet size is currently a 162, which might still be a little lean. They do get *****y in the heat, meaning don't wanna run strong. Good luck.

You're quickest and cheapest way to cure most of the problem is to put
a 165 main jet in. Cutting most the lid out is letting in some major air, I'd say you're running way lean which can damage the engine. You best bet in the long run is to get an aftermarket slip-on silencer and a bigger pilot.
Right now you're letting in a bunch of air with no way for it to escape any faster with the restrictive stock silencer. If you're waiting on the dough to come in, go get a bigger main for now and see how it runs.

[rhandw69]

yeah, you really need to open up that exhaust. Im basically at the same elevation as you are and after I installed my WB E Series with a K&N, and ran a 155 main, 42 Pilot. It ran great.