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Discussion Starter · #1 ·
I have a 2004 yfz 450 and it just barely came out of the shop from getting from getting a dyno jet carb kit put in and in 1st to 4th gears It runs so good with good throttle respond she can get full throttle And when you hit 5th gear you only get half throttle and it starts to spit and sputter almost like it's choking out what would what would the problem possibly be
 

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The problem is ur too rich on your jetting. And if im right your too rich on the main jet. What is done to it? Do you know what jet sizes they put in it?
 

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939 Posts
Dj jets are a pain in the butt
DiameterKeihinDynojetMikuni uses tapered holes to achieve flow rate
table below not 100% accurate
.025707470
.0267276
.027757872.5
.029788075
.030808277.5
.0318284
.032858680
.033888882.5
.034909085
.0359292
.036959487.5
.037989690
.0381009892.5
.039102100
.04010510295
.04110810497.5
.042110106100
.043112108
.044115110102.5
.045118112105
.046120114107.5
.047122116
.048125118110
.049128120112.5
.050130122115
.051132124
.052135126117.5
.053138128120
.054140130122.5
.055142132
.056145134125
.057148136127.5
.058150138130
.059152140
.060155142132.5
.061158144135
.062160146137.5
.063162148
.064165150140
.065168152142.5
.066170154145
.067172156
.068175158147.5
.069178160150
.070180162152.5
.071182164
.072185166155
.073188168157.5
.074190170160
.075192172
.076195174162.5
.077198176165
.078200178167.5
.079202180
.080205182170
.081208184172.5
.082210186175
.083212188
.084215190177.5
.085218192180
.086220194182.5
.087222196
.088225198185
.089228200187.5
 

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939 Posts
This is Straight from HMF

Base Recommended Tuning

165 Keihin Hex, 48 Pilot
Stock 05 needle (NCVQ) - 3rd position

Removing the Air Box lid or an aftermarket filter may require 165-175 Keihin Hex
 

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It may but those numbers are always just a base to start with. Truthfully, I think the shop that put the jets in should help you more.
 

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If the air box lid is on, take it off and see if that helps. What is your elevation?
 

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If you are swimming this much you may have more going on. Personally, I would clean the crap out of the carb which includes taking the mid section between the body and the bowl apart. Check and adjust the accelerator pump, bypass the tors just because, and then start with the base setting from HMF. To give you an idea a bone stock 07 at sea level up to 2500ft with the lid on and the exhaust baffle removed runs great with a 165 main 35 or 45 pilot (can't remember) on the 3rd or 4th clip at 2 turns out on the fuel screw. I own this bike and it is ridden weekly and you should need more fuel than that simple because you have a full system instead of a slip-on i think.
 
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