Exhaust and Jetting

[SiK^_^]

Ok if anyone remembers my topic about that graydon exhaust i was tinking about getting from a kid i finally went ahead and bought it from him the full exhaust and after reading alot on here i know i am going to need to rejet it and get an air filter im going with uni on that..i called my local motorsport shop and they said i need a dyno jet kit that comes with the main,pilot and new needle is that true i havent really seen people replacing their needle and if i do go that route whats the diff in the needle as far as advantages/disadvantages and would most people say to start at 42 pilot and 152 main? i have a 07 400ex

[ridinga400ex]

I have a dyno kit in mine.It didnt come with the pilot but i got one from my local dealer.It all depends on after you put the exhaust on.Run it to see how it feels and sounds.If it pops,and sputters alot on decel..you might to to fat(rich,to much fuel),then you must rejet to get the most out of your pipe.Mine popped,sputtered,and even had a flame or 2 shoot out the pipe.I put in the new needle they give you.It is diffrent in that it was a little longer and a the whole was bigger.I used the 3rd notch for the clip and the little spacer on the top of it as well.I then took out the 38 pilot and put in a 45 pilot.This helped with cold start issue and i was able to remove the whole choke(plate,arm,etc,).I then put it a 170 main and K&n filter with outerwears.It ran great for an hour but then at half throttle in every gear it would hesitate and it sounded like BLAP<BLAP<BLAP.I had to rejet.So I took out the main 170 and out in a 155.It ran so good and strong after that for the whole day.So use the new needle 3rd clip,42 or a 45 pilot,then a 155 main and do the air filter and airbox.It should run good and strong but your elevation might be different so a lesser or higher main might be in need.After you run it for more than an hour check the spark plug end.If it is dark black its rich and decrease the main.if it a whitish color its lean and could kill the bike,rejet using a bigger main.If it is a light brownish color your GOLDEN!!!Hope it helps.

[01exrider 281]

the new needle will help with your bottom end and it also has more clip postions on it than stock.

[ridinga400ex]

the needle,and pilot are for the idle and low end.The main is for the top end.Go with the 155 main,42 pilot,and new needle on the 3rd notch.Use the k&n filter with outerwears pre filter andyour good.

[SiK^_^]

K&N IT SEEMS ALOT OF PPL DONT LIKE THEM WAS LOOKING TOWARD UNI!