jetting setup

[bigben_002]

ive searched through most of the post but still cant find a suitable answer for what i need. I have a 400ex and am adding a hmf slip-on, uni filter, and maybe some vents in the airbox lid. I am also think of taking off the choke while i have the carb off rejetting it. What size main and pilot jet do i need and also what clip to put the needle on, i would like to stick with keihn sizes and my elevation will be around 1500ft or below, thanks for any help yall can give me

[Aceman]

I don't have a 400 so I don't know what to jet it at. Cals400ex is the one you want to talk to, he'll probably reply within a day or two. He seems pretty good at figuring what jetting to start you at.

[JOEX]

You will never get a 'suitable' answer for your specific application. There are many variables involved to jetting to get it 'just right' for a specific condition be it motor mods, weather or elevation. This goes for everyone at any location. It is triaal and error to find your own specific set up.

With a slip on and air filter the general rule is start with a 155 main jet, 40 or 42 pilot to help with cold starting then go from there. Most people say to leave the needle in the stock location, there are shims that can be added to adjust the needle by half notches.

The jet #'s I mentioned are for Keihin jets.

Joe

[cals400ex]

joex is right. jetting changes as your modifications, temp, humidity, elevation, etc all change. i personally will change my mainjet at least 3 times a year. is it needed?? no, but i am a nit-pick about jetting. joe seems to be good on his recommendations. if you just want one jet to use all year, with the info you gave me, i would just put in a 155 keihin main. with removing the choke, you will need a larger pilot jet for getting that thing started in the colder months. i am running a 42 pilot with good success. i did have the choke removed but i put it back in a while back. personally, i think it is a waste of time. also, some people have trouble starting their bike without the choke even after putting in a larger pilot, other bikes seem to start just fine. i usually find the needle in the stock position the best in the summer months. in the winter months, i like it in the 4th position. i recently ordered a washer, like what joex is saying, to be able to adjust my needle in the 3.5 position or right between the 3rd and 4th position. i haven't tried it yet to see how well it works though. i don't have a need for it right now since it is cold enough for my bike to run good with the clip in the 4th position. good luck and let us know if you have any other questions.