Should I Re-Jet, it seems to run fine?

[Hondaman90]

OK, I know this has been asked a million times, but please just give me an answer. We bought a stock 2004 400EX, and we have put a White Brothers E-Series slip-on. We just put the powerfilter on that came with the pipe on too. It seems to be running fine on stock jetting (Down my Street). I am a little worried that it may be to lean. It seems to run fine, but I haven't really rode that much since I added the filter. Do you think I should re-jet even though it seems to run fine? Thanks

[prepracing]

those power filters tend not to make one run to lean, if it runs fine then I wouldn't bother the jets. BUT just keep an eye on how it runs cause you don't wanna fry the topend by running to lean. It may even run ok now but you may have to rejet if there is a big temp./weather change :ermm:

[300exrider15]

i added a pipe to my 300ex and it did seem to run good to bu after i got it jetted it ran alot better and it seemed like the when u pushed the gas it was right there, if i was u i would get it jetted just to be on the safe side and it will probely run better too.

[coryatver]

you definitly want to put in a bigger main jet. They are on the lean side stock so with a pipe and air filter it will be lean.

[Honda#4]

i have the same pipe as hondaman90 and yesterday i put all of my discs in and wow what a lot of top end i got.would havin all the discs in and the powerfilter on lean it out alittle or i could just try it and find out i useally do a plug check every two weeks.

[MadMax27]

Check your plug. Unfortunetly, you need multiple plugs to test each range of the carb, but pulling yours now will give you an idea of were it is...

[Hondaman90]

We went and got a 155 main jet. Would that be OK to start with? Whats the most popular size jet most 400EX riders use?

[jordan_m6]

just check your plug a light brown is what you are looking for.