i need help like today

[WB400ex]

i got a 2000 400ex with white bros slip on. i want to take the lid off and leave stock filter. i didnt buy the whole jet kit but i did buy a main jet. it is a size 155. is this right for wb e series slip on with no lid and stock filter. or is it too lean. i live in san diego, california. also do i have to take the gas tank off to change the main jet. or do i just turn the carb a bit. thanx

[Glamis400ex]

Hi WB400ex,

I'm assuming you bought a Keihin jet and not a Dynojet jet. You do not have to remove the gas tank at all, here's how ya do it.

Get on the left side of your quad and find the bottom of the carb. There is a hex nut on the bottom of the carb.. Turn off the fuelcock and put a rag beneath the carb. Remove the breather tube from the crankcase (that fat black tube directly beneath the carb). Get a 17mm open-ended wrench and loosen the nut on the bottom. A little gas will come out, that's normal, hence the rag...:) Get a 6 or 7 mm socket(I forgot which) and loosen it up. Put new jet into socket and CAREFULLY thread it back into the bottom of the carb. It'll take you a few tries to figure out where it goes back in the threads. Tighten it a little tighter than finger tight. Be certain the threads aren't crossed. The jets and needle jet holder are brass and can strip/break easily, I know, I've done it. Use 17mm wrench to put cap back on bottom of carb and yer done. It's actually very easy.

As for a 155 main, I'm not sure. I have a Dyno jet kit and I run a 160, all jets are not created equal. Should be pretty close but maybe a tad fat since you still run the stock filter.

Hope this helps

Glamis400ex

[400exRacerX]

The only way to tell if the jet is too lean or rich is buy putting it in and looking at the plug.

instead of leaking gas everywhere, you can use the mfg suplied drain tube. just put in in a clean glass and open the screw on the left bottom of the carb. there is minimal gas left in the bowl.

mine ran the best with the stock jet i tried all

it's a 8mm socket for taking out the main jet i belive

[Gecko]

I just changed my main jet a few weeks ago and the correct size is 6 mm socket.

[WB400ex]

gecko is right i also used the 6mm socket. thanx u guys. glamis 400ex thanx