MOD FEVER with a need for wisdom!

[nathancarter]

I've had this 250ex for about 4 months now and I love it I have a problem though...I can't leave anything alone so I've modified it in all the performance alleys I know. I
Thought I would ask you guys about jetting and this is why. First I ordered a larger universal filter from K&n and made my own adaptor with a nice venturi like the ones at work (I work at a race team engine shop) to pack the air in. I made a filter to fit into the stock air box lid and screened it in. It measures 4x6 so it's a nice area for air to enter from under the seat and not as loud as just taking off the air box lid. I opened up the stock exhaust mid plate to have a straight through design and cut out the end of the spark arrestor. These mods have driven my jetting from stock to current. 38 pilot (stock) to 40, 95 main (stock) to 110 main (Keihin jet). These mods made great improvements without making so much noise the wife would complain. It really picks up the front end effortlessly bottom end and in the mid range. She complained when I made my own spark arrestor replacement out of aluminum and well it popped like crazy..very annoying so cutting out the end of the stock arrestor gave enough packing area to eliminate the pop. So now you know the mods but here is the issue. I investigated the air entry into the bottom of the air box to view the end of the snorkel....MAN that's a restriction. Such a large tube and a little 1" id hole. So like any red neck I cut it off on an angle to let it suck all it wanted from the side cover. Now mid and top power is decreased so jetting seams to be a culprit. I thought the 110 main would be the end of my jetting but looks like I'm entering the 115 to 120 range. What jet size would you recommend? Thanks

[member]

sell the 250 and get something faster... like a 400ex... z400 blah blah but if YOu Have to go ahead and wase ur money on the 250 thats pimp.. JMO

[nathancarter]

figured I would get this response. I mod the 250ex for fun. I've only put 30 bucks in it for the larger filter so I'm not going broke. Not to mention my wife rides this 250 so auto clutch and reverse is a must. Thanks for your imput though

[zlam27]

i know how you feel, actually i think we all do. if i could find things to tinker with, i would be in the shop every night "customizing" my 400. but keep in mind- if it aint broke, dont fix it. just have fun with it, all free mods are a welcome improvement. just play with the jetting, it will take some time but its worth it when its dialed in. good luck.

zach

[nathancarter]

Thanks Z,
It's nice to get a response like this instead of the forum filled "sale it and get a 400". Not trying to slam the ones who do this. Man I tell you if there was a name for the can't leave anthing alone itis. I have it full force.

Thanks I think I'm going to try a 120 first and see if it can digest it.

have you messed with the fuel screw? thats even if the 250ex has a fuel screw. but id just say go ahead and go with the 120 but ur just gonna have to tinker with it.

[member]

:o well...i was just tellin you what i thought.. but if u wanna mod i think there is a couple little things like new tires, maybe a pipe, but i dont know if you could get one for 130 or so

[nathancarter]

Well I went to my local atv shop got a few $3 jets and had fun. I first tryied the 120. With the 120 main it didn't bubble out or wash the spark plug off up top, but it did stumble when around 1\4 to 1\2 throttle. So I back stepped to the 115 and all is somewhat well. It now doesn't have the top end hard hit of the excellerator like the dump of gas the 120 was doing. It does seem much happier on the low to mid range though. Whellies are back to the good ole days.

[bmw500hp]

Originally posted by nathancarter
Thanks Z,
It's nice to get a response like this instead of the forum filled "sale it and get a 400". Not trying to slam the ones who do this. Man I tell you if there was a name for the can't leave anthing alone itis. I have it full force.


When I was 10 my dad bought a Yellow Honda 90. You know the type..Well, I spent all my time doing "exactly" what you are doing... what's so funny is now that years have passed one returns to "obsessing" over machines. It seems this little kid with dreams is still here some how, continually trying to improve performance in some way. Only now with a few more dollars and perhaps a little more sense...or maybe less..lol.

There's a certain type of enjoyment one gets from "10 cent" mods and "home brew" improvisions. I think so many of us have experienced this with the infamous 250x!

Have fun buddy! Regardless of opinions or outcomes, thats what it's really all about! :D :D

[ReconRider25]

you think you got it bad?:rolleyes: check this out.....and i wasent even done with it. i was gonna get tag x-5 bars with scott grips, kenda klaws tires, and a bunch more stuff like some more polishing and stuff.....but then i sold it and got a 400....except my dad wont let me mod out this one!:mad: oh well...
heres the mods:
SuperTrapp I.D.S.2 complete system
K&N filtercharger/ airfilter
Dynojet jet kit
Removed front and rear racks
Front rims flipped around(Adding about 6" of width)
2.5 in. Durablue wheelspacers in rear(Adding total of 5" width)
DG Alloy Series front bumper
Custom rear bumper
Custom support brackets for front and rear fenders
Polished throttle cover
Polished brake rezzie cover
Polished shift lever
Moose handguards
Moose shockcovers
Stickers
Rebuilt transmission(dont ask lol it broke itself...)
http://www.imagestation.com/picture/sraid93/p42f07ae84e9f7ed2073ca9ac9e6de780/fa403f50.jpg

[cals400ex]

Originally posted by nathancarter
Well I went to my local atv shop got a few $3 jets and had fun. I first tryied the 120. With the 120 main it didn't bubble out or wash the spark plug off up top, but it did stumble when around 1\4 to 1\2 throttle. So I back stepped to the 115 and all is somewhat well. It now doesn't have the top end hard hit of the excellerator like the dump of gas the 120 was doing. It does seem much happier on the low to mid range though. Whellies are back to the good ole days.


if you have the bike modded a little bit and it is studdering between 1/4 and 1/2 throttle i would move the clip down one position on the needle.

[nathancarter]

Well I'm happy now. It's pretty cold here so the main jet selection will be good the the summer. Remember I tried the 120...it worked ok you could really tell when the throttle got into the main circuit, but it was a little boggy. I ended up with a 115 which is a no bogging tire rippin wheelie givin combination. So with just cutting of the end of the snorkle I had to go up 5 numbers on the main to get right... On the needle clip position suggestion. I'm still using the stock needle and it's clip is located on the bottom slot which puts the needle at the highest location. This is the stock location too. Thanks for all you help and I hope this might help others with the MOD FEVER. HAVE FUN IN THE SNOW GUYS!!!!!

[cals400ex]

Originally posted by nathancarter
Well I'm happy now. It's pretty cold here so the main jet selection will be good the the summer. Remember I tried the 120...it worked ok you could really tell when the throttle got into the main circuit, but it was a little boggy. I ended up with a 115 which is a no bogging tire rippin wheelie givin combination. So with just cutting of the end of the snorkle I had to go up 5 numbers on the main to get right... On the needle clip position suggestion. I'm still using the stock needle and it's clip is located on the bottom slot which puts the needle at the highest location. This is the stock location too. Thanks for all you help and I hope this might help others with the MOD FEVER. HAVE FUN IN THE SNOW GUYS!!!!!


the stock clip location should be in position 3. if your on five, your either running really rich or your really heavily modified.

[cals400ex]

Originally posted by nathancarter
Well I'm happy now. It's pretty cold here so the main jet selection will be good the the summer. Remember I tried the 120...it worked ok you could really tell when the throttle got into the main circuit, but it was a little boggy. I ended up with a 115 which is a no bogging tire rippin wheelie givin combination. So with just cutting of the end of the snorkle I had to go up 5 numbers on the main to get right... On the needle clip position suggestion. I'm still using the stock needle and it's clip is located on the bottom slot which puts the needle at the highest location. This is the stock location too. Thanks for all you help and I hope this might help others with the MOD FEVER. HAVE FUN IN THE SNOW GUYS!!!!!


the stock clip location should be in position 3. if your one five, your either running really rich or your really heavily modified.

hes right stock position is the 3rd setting.

[northeast400]

I hear you!! just look under. my 400ex only has 12 hours on it.

[Bigg Pimpin]

Originally posted by cals400ex
the stock clip location should be in position 3. if your one five, your either running really rich or your really heavily modified. The 250 only has 3 positions on the stock needle and it comes on positon 3. :D

[nathancarter]

correct stock position is three...that's third from the top of the needle...not five like the dynojet needle. I'm using the stock needle on the third posistion. No problems perfect. Thats stock needle third position (stock position), 115 main jet, 40 pilot jet, 2.5 turns out on the idle screw. I'm happy

[cals400ex]

what is up with only having 3 positions. and why would they put a needle in that is adjusted all the way up (clip all the way down) from the factory? this gives no room for improvement when you add mods.

[nathancarter]

I was kinda surprised myself that it came stock in the fastest position.