Dynojet

[400exr]

Well for last five months I've been trying to get my jetting right, but I haven't had much time to tinker with my bike. So after alot of head scratching and swearing, today I think I finally got it perfect, well almost. When I first got the kit the Dynojet instructions told me to go with a 170 main jet, well I thought that was kind of high so I went with a 165, and it ran O.K. Well then I got a sparks timing key and while riding it hard I noticed the header would glow and the other thing was I couldn't beat a stock 400. So, I phoned Dynojet and they told me to go with a 170 main like the destrutions said. So I put the 170 main in, and it ran fine, the plug was a tan color, and the header didn't glow anymore, but the bike felt slugish like I couldn't top it out. Well then today I got to thinking that the higher the altitude the less dense air there is, so being that I live 4200 feet above sea level, I put in a 160 main. Wow:eek2: I think that helped a lot. I could top it out and the plug test was a nice tan color. What I'm need to know is, do you think I'm gong in the right direction by going down in the main? Sorry for the long post and thanks guys(or gals) for any help I get ;)

[JOEX]

Higher elevation = smaller main jet, from what I understand.

Did you tell Dynojet your altitude when you requested jetting info?

Joe

[400exr]

Ya, I told them my altitude and everything else. It seemed like really bad customer service :(

If it's not backfiring or boggin on the topend then your fine..;) Your motor will tell you what to do better than the people on the phone will.:eek:

My motor is far from stock. I have a 2 inch hole in my airbox lid and I run a 155 main dynojet with a full exhaust. :eek2:

[cals400ex]

yep, i am with rico. i would try even a smaller jet. if your headers are glowing at idle or 1/8 to 3/4 throttle, it isn't your mainjet. it wil probably be your pilot jet/fuel skrew or your needle/clip position.

[400exr]

Thanks guys for your help :) I think I'll try going down in the main till It gets lean and go up one.