HMF slipon jetting for 400ex?

[Poston5]

what all jets will i have to change when i put the HMF slip on on?i know the main jet will need to be changed but anything else?i have 6 1" holes in my airbox lid with vents and a k&n filter,what will i have to up my main jet and other jets if any too?
i live in central ohio,im not sure of the elevation.temperatures vary 30*f-80*f.will i have to switch jets from winter to summer?
i was thinking about the dyno jet stage 2 jet kit or the HMF jets?where can i get eaither of these at online?thanks

[phebus]

Save yourself some money, and buy keihin jets. Buy a 155, 158, and 160. Use the smaller jets when it is warm, and the bigger jets when cold (dense air). If it is hard to start, you might want to up your pilot to either a 40, or 42.

[MOFO]

I agree with the guy above me, but I would change your pilot jet no matter what...go with a 40 or 42 for sure. Makes a huge difference with cold starting.

[Dunesurfer]

Originally posted by phebus
Save yourself some money, and buy keihin jets. Buy a 155, 158, and 160. Use the smaller jets when it is warm, and the bigger jets when cold (dense air). If it is hard to start, you might want to up your pilot to either a 40, or 42.

What he said.:)

[Poston5]

I am kinda new to this jetting stuff and i dont really understand it. All of the dealers around me want 60 bucks to rejet my 400ex with a k&n filter and a HMF slip on exhaust also i have air box vents. If someone has this done to their 400ex please tell me what i need to do. As ferom what i have been told on here is that i need to up my pilot to a 42 and up my main to around a 175 and move my clip up some but i dont know how much. anybody with a set up like mine please help me out

[cals400ex]

use a 42 pilot and a 155 main in the winter and a 152 in summer. that is what i would start with. go to the faq forum on this site and click on how to install a K&N powerkit. it will take you through all of the steps for installing both jets. these two jets are right next to each other in the carb.

[goinhonda]

do it urself pal.ull learn how to do it and save 60-110 bucks.crazy that sport cycles want that much to rejet. ill help you friend.lol

[phebus]

Go with Cal's advice, he know's his stuff. The jetting you listed sounds way too rich. Like he said, go to the tech section and learn how to do it yourself. Jetting is something you have to play with for your individual application (weather, altitude, and every motor combo acts a little different). The odds are the dealer wouldn't get you right on, and you would be sacrificing performance by running whatever they jetted to, rather than trying different set-ups to determine what really works best.

[phebus]

One more thing. At first it all seem's a little intimidating, but once you do it, you will see how easy it really is. There is no substitute to working on your own stuff.

[smount101]

Hey man, i have a very similar setup... 03' 400EX with a K&N and 6 vents in the airbox... i bought a used fmf megamax II that is on its way but i plan on switching to an hmf also.... i called fmf and told them my mods and location(which is ohio also) and they told me to switch to a 42 pilot and 155 main and leave the needle in the stock position... i think 155 may be a little too rich so i think im gonna go ahead and buy a 152 and 155 (keihin) once i try them out i'll let you know what i found out.

[cals400ex]

Originally posted by smount101
Hey man, i have a very similar setup... 03' 400EX with a K&N and 6 vents in the airbox... i bought a used fmf megamax II that is on its way but i plan on switching to an hmf also.... i called fmf and told them my mods and location(which is ohio also) and they told me to switch to a 42 pilot and 155 main and leave the needle in the stock position... i think 155 may be a little too rich so i think im gonna go ahead and buy a 152 and 155 (keihin) once i try them out i'll let you know what i found out.


you probablly won't notice the difference between the 152 and 155 mainjets. the leaner one (152) may have a tad bit more top speed, but you don't want to push it from running too lean. however, with a slip-on, i would put in a 152 and not worry about it. i have good luck with my needle in the stock location in the summer months and i move the clip down one position (richen 1/8 to 3/4 throttle positions) in the winter months. good luck

[GA400ex]

You will have the same setup as I do if you run the dynojets -- 04 400ex w/ HMF slipon, K&N with outerwear, modded airbox lid, and Dynojet stage II. My elevation is close to sealevel and during the winter months, 30-60 degrees, I run a dynojet 160 main. During the summer, 60-95 degrees, i run a 155 main. By the way, the DynoJets are made to run with the stock pilot.

[cals400ex]

Originally posted by GA400ex
You will have the same setup as I do if you run the dynojets -- 04 400ex w/ HMF slipon, K&N with outerwear, modded airbox lid, and Dynojet stage II. My elevation is close to sealevel and during the winter months, 30-60 degrees, I run a dynojet 160 main. During the summer, 60-95 degrees, i run a 155 main. By the way, the DynoJets are made to run with the stock pilot.


you bet that the dynojets can be used with the right pilot jet. however, that doesn't mean that the stock pilot is the right one for your bike. if your lean on the pilot and are around 2.5 turns out on the fuel skrew, i would get a larger pilot jet.

[tinner]

I would just go and buy the hand full of jets. They are around $4.00 a piece compared to the $60.00 jet kit. The pilot jet..if I remember correctly is a little more (around $8.00?), but well worth it. Your machine won't be so cold blooded.

[GA400ex]

Originally posted by cals400ex
you bet that the dynojets can be used with the right pilot jet. however, that doesn't mean that the stock pilot is the right one for your bike. if your lean on the pilot and are around 2.5 turns out on the fuel skrew, i would get a larger pilot jet.

Sorry cals, I know that you are the man when it comes to jetting. I wasn't trying to say that a different pilot couldn't be used, I was just stating what DynoJets instructions say.

[kwatts400]

I went with the dynojet kit on my old 400ex. I was running a pro-circuit slip op, k&n filter, & open air box. I just put in the jet that they suggested with there kit and it worked great.

[cals400ex]

Originally posted by GA400ex
Sorry cals, I know that you are the man when it comes to jetting. I wasn't trying to say that a different pilot couldn't be used, I was just stating what DynoJets instructions say.

no problem. i wish i knew everything about carbs. it just seems like i have jetted mine so many times i know how MY bike runs. your absolutely right though. the stock or a larger pilot jet can be used. i was just trying to clarify that a bigger one might be needed even though the stock one can be used. good luck :)