Jetting w/ K&N & Supertrapp IDS2

[400exJOE]

I have a 2001 stock 400ex, and just put a Supertrapp IDS2 slip-on on it. I have a K&N filter, prefilter, and Dynojet kit. It says to run a 170 jet, but when I did that it fouled my plug. I put a new plug in and jetted it to 165. It ran fine for 5 min and I left it idleing to warm it up before I checked the plug. It stalled and didnt want to start. When I checked the plug it was black. I then tried a 160 and it didn't want to run. It was also cold and damp when I was working on it.(Dont know it that changes anything). I live in Upstate NY. If anyone has a 400ex w/ a K&N, Dynojet kit, and Supertrapp please let me know your setup. Thanks a lot

I don't have experience with an IDS2 on a 400, BUT how many discs are you running? I've found that you need to run most of th discs to run well and go down one jet size in the dynojet kit from recommended for aftermarket pipe.:o Just my opinion with limited exp. with IDS2's and dynojet kits.:D