I have am putting a dynojet kit on my 400 EX(with a K&N airfilter and stock exhaust), and according to the instructions it says to use the DJ142 main jet. The stock is a 148, if it is lean shouldn't I be going up in sizes instead of down? I was thinking I needed to go to a 150 but they don't have that, they either have a 146 or a 155. I live in Ohio(around 600-700 feet). Can someone explain?!? Which jets did you use? Thanks.

 

Odd. Guess that is for the lid on instructions. My DynoJet instructions said to use the 165 for air filter mod and stock exhaust. Of course this was for airbox lib off and below 3000 feet elevation. Same set up with an after market exhaust was to use the 170 main. New needle on third groove for both.

I was impressed with the noticable difference this cheap mod made. I got the K&N PowerKit. Filter, lib off, jet kit. I also did the rev box at the same time. Nice for $200.

 

ok i live in ohio also now im totaly lost........i have been told so many diff thing on jetting ,what size to use and so on it not funny
all the way from dont change the stock jetting to only goto 150 mian know you guys say a 170 main grrrrrrrrrrrr someone please tell me what to use
mod i have is K&N filter with 6 vent hole in air box lid a FMF powercore IV 2 pipe im running lean i think losing power backfire some and a weird smell from ppipe HELP me i need to jet soon

 

i to was stumped on the dyno jet kit. when i got mine i put on a pipe and k/n and it called for a
146 jet and i knew that the stock jet was 148 and
i thought no way in hell go smaller. so i called
the 1-800 number for dyno jet and they told me its
a toltaly differnt set up they use there own numbers.

as for you (a400exer) the 142 is the right jet,
you take the stock jet out then put in the adapter then the 142 jet, put the clip in the 3
notch from the top on the needle they sent you,
the air fuel mixture screw 3 and half turns out

and (lucis) 155 jet it will be close

 

426ex is exactly right. The dynojet kit uses a different numbering system, dont confuse the numbers with the stock jet numbers. I have used the kit with a couple of my quads and I am very pleased with the results of the kit.

'00 400ex
'99 426ex
'99 Banshee
'96 300ex

 

Thanks 426ex & Trxoutlawz!! A was hoping to hear something like that! I tried to call myself but they aren't open on the weekends.

 

Now the $100 question:

What honda jet is equal to the dynojet 142, 146, and 155?

 

Jetsport,
To answer your $100 question.... I do not know which one is equal to the stock size as far as the volume of fuel to go through it. The reason is it does not matter, because with the dynojet kit you are changing the needle. You have a different taper on the needle, which means a different ratio of fuel at a given throttle position.

 

I've used the K&N Dynojet kit here at 6,000 feet using jet number DJ138 and at Glamis (below sea level) using DJ142 with the K&N filter, precharger and stock exhaust, and my 400EX ran great. Just follow the instructions.

 

Hey, I put the kit on like it said, and then a stock 400EX(with a rider who was 60 lbs more than me) was a little bit faster on the top end!!!! What's up with that? We have raced before(on a back road) and I was a little bit faster BEFORE the kit. Is it too rich now? Any suggestions, help? THANKS!