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Discussion Starter · #1 ·
Hey i'm new to the forums and my name is jake..i just recently bought a green 250 ninja and decided to do some work on it with my grandpa whos a mechanic. I bought a yoshimura slip on and dynojet kit 2193..we installed both and they both work great but something just doesn't feel right..the bike rides fine but at higher rpms its stutters just a little and i've actually lost top end speed with both of them. I followed the directions for both things very accurately so i'm not sure what to do?

any advice would be great :)
 

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Hey i'm new to the forums and my name is jake..i just recently bought a green 250 ninja and decided to do some work on it with my grandpa whos a mechanic. I bought a yoshimura slip on and dynojet kit 2193..we installed both and they both work great but something just doesn't feel right..the bike rides fine but at higher rpms its stutters just a little and i've actually lost top end speed with both of them. I followed the directions for both things very accurately so i'm not sure what to do?

any advice would be great :)
what are your jet numbers?? maybe that particular Jet isn't right for your bike.
When you say stutter do you mean
1. you hold it at constant throttle and it sputters
or
2. when you are rolling on the throttle there is a lag?
 

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Oh yeah, hi jake, I am the resident jerk. Can't help you with the specifics of jetting, but once you figure out whether your bike is lean or rich and at what speed/rpm range, that will give others a good idea to pin point your problem
 

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Discussion Starter · #4 ·
The stock jets in them were 98 so i put 100 in them...its mainly a lag..but before i installed them i would be going 55 at 6,500 rpms..now its up to 7500
 

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do a search using "dynojet"... there have been some very good posts about specific jetting numbers, but they are scattered among many different posts.

Your 100 main sounds about right, though (IIRC)... what is your needle clip position set to?
 

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Discussion Starter · #7 ·
my needle clip is set to what it said to..which is believe is the 3rd groove from the top. I tried adjusting my clutch but that didn't seem to help..
 

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my needle clip is set to what it said to..which is believe is the 3rd groove from the top. I tried adjusting my clutch but that didn't seem to help..
as dirk mentioned... read the links he provided, especially this one on how to select a main (step 4.1)... http://faq.ninja250.org/wiki/How_to_fine-tune_your_jetting#Step_1:_Find_the_proper_main_jet

jetting is more of an art than a science to get it right. What DJ gave you is a rough starting point, you need to fine tune your bike according to your individual riding style, conditions and location.

btw, where are you and what's the altitude?
 

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Discussion Starter · #9 ·
I like in arkansas..idk the altitude but its been in the 90's everytime i ride..i read the thread about how everyone's tach seems to be the problem..I'm going to call the dealership tomorrow and see if they will just fix that and that should fix the problem.
 

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I like in arkansas..idk the altitude but its been in the 90's everytime i ride..i read the thread about how everyone's tach seems to be the problem..I'm going to call the dealership tomorrow and see if they will just fix that and that should fix the problem.
There is your problem, with that kind of altitude you need to call Yosh and Dynojet and tell them you're in the clouds.
 
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There is your problem, with that kind of altitude you need to call Yosh and Dynojet and tell them you're in the clouds.
Enzo he didn't specify the units! If he's talking feet then 90 feet above sea level isn't too bad. If he's talking miles then yeah not too much oxygen to work with up in the stratosphere :D.


JGoode you should consider something like nitromethane or rocket fuel. That'll rid you of those pesky oxygen problems!
 

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try putting the stock 98 jets back in and test it. i'm still on the stock jets and i have a full AP exhaust. my elevation is about 400'. plugs are tan. check your plugs and see what they look like first.

also he stated he didn't know what the altitude is where he lives, and the temp is in the 90's. u could also go to a dyno and see what it reads so u know where to make your adjustments also.
 

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Discussion Starter · #14 ·
I believe the altitude here is 311 feet...i'll try putting the stock jets back in when i get a chance..theres a dyno place around here that i might run by to have them test it.
 

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I believe the altitude here is 311 feet...i'll try putting the stock jets back in when i get a chance..theres a dyno place around here that i might run by to have them test it.
I agree.. try going back to your stocks and see if that helps.

also, the DJ numbering system is not the same as the Keihin system so you went to a Keihin equivalent 102.5 when you changed to the DJ 100.


Width------Keihin # -- DynoJet # --- Mikuni #
0.0350---- 92.5--------- 92----------- 86.3
0.0360---- 95----------- 94----------- 88.1
0.0370---- 97.5--------- 96----------- 90.0
0.0380---- 100---------- 98----------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104---------- 97.5
0.0420---- 110--------- 106---------- 99.4
 

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yeah if the bike pulled harder up top before u jetted it i would go back to stock with the needles on the 3rd position to start.
 

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Discussion Starter · #17 ·
hmm..well kkim that could be the problem with why it lags a little at higher rpms..besides that it drives good..I'll switch it down to Dj 98 and see if that makes a difference..But as for the rpms being about a 1000 higher i believe that to be in the tachometer. Is it fine for me to drive it the way it is or should i change them immediately?
 

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hmm..well kkim that could be the problem with why it lags a little at higher rpms..besides that it drives good..I'll switch it down to Dj 98 and see if that makes a difference..But as for the rpms being about a 1000 higher i believe that to be in the tachometer. Is it fine for me to drive it the way it is or should i change them immediately?
If the problem is that you are running too large of a main with the DJ 100, that means you are running a bit rich. You should be fine (rich is better than lean). The downside is that you may foul a plug if is too rich. My guess is that you should be fine. If the bike starts running ratty, take the plugs out and clean them which should fix the fouling problem until you get a chance to replace the mains.

Have you seen the post by Vex (post #20... http://www.kawiforums.com/showthread.php?t=115107) that shows you how to replace the mains w/o having to take off the carbs?
 

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the problem is that you are running too rich on your jets. the dynojet 098 main is bigger than the stock 098. with the snorkle removed and the yoshi installed, you need to use the dynojet 098 mains.
 

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Discussion Starter · #20 ·
Alright well i'm going to change them out to dj 98's..but question..does this void my warranty since i'm doing it or should i have someone else do it? I'm bringing it in in a week to have it looked at (the tachometer) to see if they will replace that possibly..I haven't removed the snorkel because I was unsure if i should but I'm guessing i need to now. If its going to void it ill put the stock jets back in when i take it in just in case.
 
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