missing out on top end

[new03400]

i have a brand new 03 400ex that i bought 2 weeks ago wed...got a heck of a deal on it! anyways i have rode about 4 or 5 tanks of gas thru it, and changed the oil & filter once (mobile 1 red cap) it is stock as a rock, and every since i have had it, it has been a beast on the bottom end, i can bust my buddies 01 400 with the same gearing (15/38) full supertrap/powerbomb exhaust, jetted, k&n, uni-airbox vents, and tc rev box, from a dead stop and a roll until 5th gear and it seems that mine is just at a loss for power and he just trucks on past me, i have about a 3 bike lead on him, we can switch bikes and same results. im not trying to bragg on mine but i think its a "factory freak" i guess you could call it....

well tonight i took it out for a ride, gas was about 1/4 tank so i put some gas for our lawn mower in it, prolly 2 or 3 months old id say..because i was out of my 93 & outlaw mix... it ran good for about 15 mins then when i would go up thru the gears it would start to "miss/hesitate" at the top of 3rd, 4th, 5th...id clutch it rev it up then go again it would pull real hard up till 4th then start to do the same crap...

ever since ive had it (2 weeks) i ride it at night sometimes, and i see that my header pipe glows red about 4-6inchs down?!? is this common?

my main question is do you think that the gas i put in might be causing my miss? and its also 87 octane


feed back would be great!!

thanks for your time,
steve

[mojoe2878]

the gas is probably all it is. it being old isnt any good. putting 3 month old 87 octane in any thing wouldnt make it run worth a crap. if my gas sits up for more than 4 weeks i pour it out and get fresh gas. gas does have a shelf life.

[47501exracer]

Doofus,

400ex's require premium gas. Don't put any 87 in it. I would drain the tank out and fill er up with 93 or 94.

[Big - D Racing]

Why the he** did you put old gas in it. First bad thing you did was put in 87, that'll causing pinging. Old gas loses its octane rating, so that gas was extra bad for your engine. It will defintely cause your bike to run like junk. Was your piping glowing red before you put in that crap gas? If so it is defintely your jetting, you are running to lean:rolleyes:

[cals400ex]

as far as the speed of both bikes, adjust the throttle cables so there is only around 1/4 inch of slack in the lever.

[Quad Dude]

if your head pipe is glowing red. go it and check your jets make sure there not pluged and get some new gas

[new03400]

i totally agree on me being stupid for putting in 87 octane gas..but i wanted to ride and the bike was about empty, i know stupid mistake...

well today when i got home from work i completely drain the tank, reserve side too, and put in fresh 93 octane and rode it about 20 minutes, but it stills does the same thing miss/hesitate at the top of 3rd, 4th, 5th...

i took off my airbox lid and MAN it did it top of 2nd - 5th...my bike is stock as a rock, and yes the header pipe had glowed red before the crappy gas, do you think im jetted to lean? even coming from factory?

like i say down low it will pull the wheels and carry them first three gears then just seems to level out, not pull anymore then start the miss/hesitate crap!

help!
steve

[bradrenea]

Sounds like maybe the old gas had some dirt or something in it that has clogged your needle/seat. You might try taking the carb apart and blowing out all of the fuel circuits.
Or if its brand new and bone stock take it back to the dealer and tell them its done it since you got it. They might fix it under warranty.

[mojoe2878]

Originally posted by new03400




i took off my airbox lid and MAN it did it top of 2nd - 5th...

steve [/B]

if it is jetted too lean, which they often are from factory, then running it with the air box lid off is just gonna make it more lean.

[new03400]

i plan on getting a hmf slip-on or full system...still trying to find out if the full system header is any better than the stocker, k&n air filter & outerwear, and uni-air box vents, along with a gt thunder rev box...

im going to rejet, but should i go ahead and rejet for the pipe and other mods to come in the future? or just jet up for the time being..all mods will come within the next month(ish).

thanks alot,
steve

so you think jetting is my pain problem?

[cals400ex]

i would start by taking the carb apart and cleaning it.

[new03400]

i changed the spark plug, (DPR8Z)...problem seems to be fixed!

im going to order a hmf slip-on- power bomb header- k&n airfilter and outerwear- tc rev box- delete choke and vent my air box (Uni-vents),

i live in southeast missouri, so which jet do you think would suit me best? (main/pilot)

cals i belive you are one of the better jet judger, anybody?

thanks,
steve

[Rider#11]

go up a main jet size or 2 and see what happens...or try larger

[cals400ex]

with those mods:

155-158 keihin main jet (a jet kit is sized differently so mention if your going to buy the kit or individual keihin jets)
stock needle clip position in summer. drop the clip one position in winter.
42 pilot jet
2.75 turns out from lightly seated on fuel screw