Jetting

[blazinslow]

I curently have a 02 400ex with full yoshi system, aluminum airbow w/ lid but 2 two inch holes in the top, kn air filter and high rev box. I am getting some black smoke but it dosent smell like its flooding up kinda like a burnt smell but only dose it when I sit and rev it up. Also smoke comes out of the pipe when i cut it off. So I am thinking jets but could be wrong. Any help with where to start w/ jetting would be great.

[cals400ex]

what jetting you at now?

[blazinslow]

Im not sure the guy I bought it from said it had a dial a jet kit but not sure what sizes.

[wvspeedfreak]

I have basically the same set-up as you and I am running a 158 keihin main and a 42 pilot.Seems to work well.

[cals400ex]

that dial a jet may jack things up. i am not sure how they work exactly but it has something to do with air flow. your either going to figure out how the dial a jets work or get rid of it. we could get you dialed in pretty good if you didn't have that thing. i am thinking you need a new air boot from your carb to your air box if you get rid of that thing. i don't know if the 17mm screw on the bottom of the carb was modified with that dial a jet either. if so, you may need a new one of those also if you remove it.

[blazinslow]

I have a brand new dynojet kit here somewhere if I find it I am just going to go by my elevation and start over using the instructions. What is the difference between a dial a jet and normal jets anyway.

[miken]

Dial a jet....................http://www.thunderproducts.com/dial_a_jet.htm

Mike -

[blazinslow]

Ok I just got everthing back together. He did not have a dial a jet kit. In fact I belive it was stock. The c-clip was on the 2nd notch, with a 142 jet in and also while I had it all apart I changed my plug witch the finger on top of electrode was burnt off so im sure that was most of my problem. What I did was moved the c-clip to the 3rd notch and put a 170 jet in, which was recomended by dynojet for my elevation, and the air mixture screw 3 1/2 turns out. It fired right up w/ little black smoke at first but cleared right up. Thanks for all you guys help.

[cals400ex]

Originally posted by blazinslow
Ok I just got everthing back together. He did not have a dial a jet kit. In fact I belive it was stock. The c-clip was on the 2nd notch, with a 142 jet in and also while I had it all apart I changed my plug witch the finger on top of electrode was burnt off so im sure that was most of my problem. What I did was moved the c-clip to the 3rd notch and put a 170 jet in, which was recomended by dynojet for my elevation, and the air mixture screw 3 1/2 turns out. It fired right up w/ little black smoke at first but cleared right up. Thanks for all you guys help.

no, he must of had a dynojet kit, not a dial a jet.

[t boy]

:huh i have put on my 400ex. procuircet header slip on pipe 11to1 piston stage 2 hot cam addvance revlimed{cdi} open air lidbox kn air filter i have a dino jet kit. i am using the 170 jet i am at sea level. is this the right jet size.

[cals400ex]

Originally posted by t boy
:huh i have put on my 400ex. procuircet header slip on pipe 11to1 piston stage 2 hot cam addvance revlimed{cdi} open air lidbox kn air filter i have a dino jet kit. i am using the 170 jet i am at sea level. is this the right jet size.


some will say you need that big but most will say that is just too big. with your mods i wouldn't go over a 160, but that is just me.