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Question about my jets
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Posted by: kolby2004

My sig pretty much sums up all my mods. I bought my 400ex about one year ago and never opened the carb untill now to do a quick cleaning and found out that my jets are 45 pilot jet and 155 main. I am having some issues. I notice the problem the most when doing a wheelie in 1st gear and once I get the front end up and just blip the throttle it seems to just cut out and the front goes back down. Or anytime I let off the throttle and then get back on it real fast it seems to cut out. I am guessing the pilot jet is too big. What should I go down to? I have a 42. Should I try that one? It seems to run good other than that. 155 seems small on the main but seems to run good. should i try anything different on the main too? Thanks

Posted by: FoxHondaRider

whats the adjustable needle do on the stock 400ex?

Posted by: kolby2004

I dont know actually. I didnt check that.

Posted by: FoxHondaRider

does it mean i dont even have to buy a jet kit?

Posted by: CarGuy7a

the adjustable needle just meters how much fuel passes through the main jet at full throttle riding and has no effect on idle fuel metering. it's a small adjustment. lowering the clip on the needle richens the main jet while moving the clip up leans it.

2005 and later model carbs have a needle but it is not adjustable.

now to answer the question "does it mean i don't even have to buy a jet kit?"

that all depends on the mods and motor work. if you need a bigger size jet due to performance exhaust, filter, cam etc. you can either buy the hex keihin style individual jets in larger sizes than stock jets (in which you will not need to change the needle because it's keihin brand).

now if you get a jet kit such as dynojets. you will need to install the dynojet needle.

^^^ the reason for this is because the 2 different brand jets meter fuel differently and the proper needle is needed to obtain the optimum fuel delivery.

sorry for the long post hope that helps