Another 400EX jetting problem =-)

[HondaRacing23]

It doesnt matter what jet i put in my bike it dont run for **** on top end. it dont run bad it just dont run as good as i think it should. I have a 155 in it now. someone told me to put a 148 in it but thats not enough if u ask me. im going to try a 160 with 2 1/2 turns out on the air screw. my air screw now is on the 3rd should i put it on the second? i need some help. im going to the dunes in silver lake MI on June 3rd and 4th and want it to run good because in the past years it sucked bercause it ran horrible. help me guys i know u can =-) thanks:confused: :confused: :confused:

[cals400ex]

i would try to take the carb off and clean it really good. put in a 160 keihin main, put clip on 4th position on the needle and try a 42 pilot jet at about 2.5 turns out. make sure your clip on the needle is in great shape or just replacing it would be best actually. also, make sure you can see about 3 threads on the needle jet holder (the piece that the mainjet skrews into) when the nut is tightened down.

[HondaRacing23]

ok thanks man. i will try that hear in a few days and post a reply and tell you how it worked. i really dont want to have to take the air box lid off so im trying to get it so i dont. thanks

[HondaRacing23]

I put a 160 in with the 42 pilot and the air screw on the 4th. on top end it seems to run ok on bottom end it seems to stutter a little bit. I put straight racing gas in it and thats when it started running ****ty. it seemed to run ok with just 93. could running straight racing fuel (110) cause it to run like that. it seemed like it was running a little to hot too. could this happen? im going to drain all the gas out tomorrow and just run straight 93 and see how it goes from there. Im hopping it runs ok. IF NOT what do you think it could be? thanks..

[660RaptorRider]

i think you have to rejet for running race gas. It sounds like it makes it run leaner in your case maybe because it burns better im not too sure.

[KASCHAK]

race gas makes it run cooler.. and if it can run cooler you can run richer..

with the mods below i have 4pos on the clip 2 turns out on screw 165 and 42 pilot

its really hot here so i have the 165 in when its cooler i put in 168

[HondaRacing23]

DO you run straight 110 or do you do a 50/50 mix with 93? If i just run 93 my bike should run just fine with my jetting right? or if I even put a gallon of 110 and 4 gallon of 93 should be fine too? let me know dude. thanks

[seven]

If those are your mods in your sig I would try a 165-170 main depending on elevation. I am at 2400ft and every modded 400ex around runs in the 170-180 range.

[chadmel]

You may want to have your valves checked to see if they need adjusting. That could hurt top-end.

[HondaRacing23]

I have already had them ajusted after having my 426 put in. They were loose and he tightend them up. NOt cheap either for something simple to do to. i am in ohoi and below 5000 feet not sure the excact feet. im going to try to run a gallon of race gas(110) to 4 gallons of 93 and see how she runs. my friends bike bone stock motor with an FMF full system runs that and it seems like it ran just as good if not better. if that dont fix my prolem them im going to run staight 93 and then go from there. i may try sticking a 165 in i dunno. it seemed like it ran pretty good with a 155 clip on third and 3 1/2 turns on the air screw it just seemed like i didnt have that much on top end was getting smoked by a stock Z and a stock artic cat 400.:confused: :confused:

[cals400ex]

what size tires you run? what gearing you run? what type of riding you do? go and look at your throttle lever. push it in and see how much play is in it. make sure you have no more than 1/4 inch. don't go much less though either. also, it seems like your bike could use a little bit more cam.

[HondaRacing23]

22x11x9 tires,stock gearing,i am already running a hot cam stage 1 cam i dont think i need to go to a 2. I ride mainly trails and hills and dunes 3 for times a year. my throttle looks fine. im going to test it out this weekend and go from there. thanks for all the help

[quadrider400]

We have similar mods and I have the same feeling that top end is lacking .... I went to a 14 tooth front sprocket... while it decreases the top end in theory it allows you to get to top gear and makes the lower gears better.... Most important with the large rear tires you are running compared to stock... I do the same for woods to get ground clearance.... but it kills any racing with a "stock" bike.... the other way to help fix this is my next step which is to add one tooth to the rear... this will again work to get me closer to stock gearing with larger tires.
I have found that the ground clearance and low gearing is far better than than top speed in the woods.

Later Craig...:p

[cals400ex]

with your 22's in the back i would get a 14 tooth front or a 40 tooth rear (given this fits without clearance problems). these will get you back to similar gearing as a stock bike

[HondaRacing23]

im pretty sure im already running a 14 on the front if its not 14 its 16 but im almost sure its 14 ill have to count them. as for the back im running a 38 which is stock i beleive. ill go with the 40 and try that but i do a lot of hill climbing will that extra 2 teeth change antyhing or anything noticeable? thanks guys for all your support...:) :blah:

[cals400ex]

i thought you said you were running stock gearing?? stock is 15/38. i wouldn't get a new rear sprocket until you figure out what front you have on.

[HondaRacing23]

Im pretty sure its 14. Ill check and let you know