I went to my local yamaha dealer today, trying to get a 155mj, and 40 pilot for my 400ex, since the closest honda dealer is 45 minutes away. They said they couldn't help me because there are different style of jets. I thought a 155 was a 155. guess not. Or is this dealer just pulling my leg. I know the yamahas use mukuni(sp?)carbs and the honda uses a kehein(sp?)carbs. Will the "yamaha" jets work?

I have three 3/4 inch holes in the back of my stock pipe, behind the baffel, and was planning on drilling a 2" hole in my stock air box lid with 2" diameter pipe going down into my air box, with the hole facing away from the filter so water wouldn't go on the filter if i go in water. Then I was going to go with a 40 pilot, put the needle on it's 4th richest setting, and a 155 main or so. Maybe a 152 or 158. What do you guys think?