WR400/426/450 Jetting Database

Year: 2002

Model (400 - 426 - 450): 426

Cam Timing (WR/YZ): Decomp cam, don't know if it's WR or YZ

Main jet: 168

Pilot Jet: 42

MAJ: 200

PAJ: 75

Leak Jet: NA

Starter Jet: 65

Fuel screw (turns out): ~2 1/2

Needle Model/Clip position: OBEKQ 4th clip

Grey Wire Mod (Y/N): NA (NZ model don't have it to stat with)

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): ?

Airfilter Brand: Stock

Exhaust Brand: Staintune

Average Altitude: 0-1000 ft

Average Temperature: 5-25 deg C (41-77 deg F)

Average Humidity: 60%

Degree of Satisfaction (0-10): 4 (hopefully will be a 10 when I sort out the jetting)

Additional Mods/Comments: BK mod to bring AP squirt down to 1/2 a second (was about 2 seconds). Idles alright, stumbles all over the place at 1/4 - 1/2 throttle (needle I'm guessing, kinda new to this tuning thing, probably gonna get the JD kit), pulls strong at 1/2 - full throttle but a little on the lean side (plug test). Only just bought the bike, need to get this jetting sorted out so I can see what it really can do!

Year: 2005

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): stock - WR

Main jet: JD - 165

Pilot Jet: stock - 45 (I think)

PAJ: stock - 80

Leak Jet: stock - 50

Starter Jet: - stock - 65

Fuel screw (turns out): zipty - 1 1/4

Needle Model/Clip position: JD - red 4th from the top

Grey Wire Mod (Y/N): YES

TPS Connected (Y/N): YES

Airbox Snorkel/Lid (on or off): OFF

AIS Removed (Y/N): YES

Airfilter Brand: TwinAir

Exhaust Brand: Stock w/ GYTR Performance WR Muffler Insert

Average Altitude: 6000-10000

Average Temperature: 60-80

Average Humidity: DRY

Degree of Satisfaction (0-10): 10 - I LOVE THIS BIKE! :thumbsup:

Additional Mods/Comments: Suspension re-sprug and re-valved for a 210 lb B Enduro rider, Rekluse clutch w/perch adjuster, 14-49 gearing, DID X-Ring chain and Renthal sprockets, Acerbis 3.3 gal tank...

I love this bike... I tried putting an 06 YZF exhaust cam in it and it just killed the bottom end.....so I don't recommend it...

Year:'07 WR450F

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ):WR

Main jet:165

Pilot Jet:45

PAJ:Stock

Leak Jet:40

Starter Jet:Stock

Fuel screw (turns out):ZipTy 1.5 Turns

Needle Model/Clip position: JD Red 4th slot

Grey Wire Mod (Y/N):y

TPS Connected (Y/N):y

Airbox Snorkel/Lid (on or off):off

AIS Removed (Y/N):y

Airfilter Brand:stock

Exhaust Brand:stock uncorked w/sparky

Average Altitude:1500-5000

Average Temperature:75-100

Average Humidity:under 20%

Degree of Satisfaction (0-10):So far 9, as there is always room to improve. I love this bike.

Additional Mods/Comments:

Year: 2001

Model (400 - 426 - 450): WR 426

Cam Timing (WR/YZ): WR timed

Main jet: 168

Pilot Jet: 45

PAJ: 100

Leak Jet: NA

Starter Jet: 65

Fuel screw (turns out): 2 turns out

Needle Model/Clip position: JD Red #4

Grey Wire Mod (Y/N): Yes

TPS Connected (Y/N): Yes (not re-adjusted from factory)

Airbox Snorkel/Lid (on or off): Airbox lid off

AIS Removed (Y/N): NA

Airfilter Brand: Twin Air w/ No-Toil Oil

Exhaust Brand: Stock, with GYT-R Insert

Average Altitude: 700ft (Michigan)

Average Temperature: 70-90 F

Average Humidity: 70-90%

Degree of Satisfaction (0-10): 9 (we can always want more can't we?)

Additional Mods/Comments: Additional mods:

Light Blue Wire

O-Ring Mod (WAY better than BK Mod for me)

ACV disabled (which is why I have a 100 PAJ rather than a 75 stock)

Just did the O-ring mod, and it took my degree of satisfaction from a 6 to a 9!! Can't say enough about the difference it made. Almost made it run like an open exhaust.

Year:2007

Model (400 - 426 - 450):450

Cam Timing (WR/YZ):WR

Main jet:168 (162 stock)

Pilot Jet: 48 (45 stock)

PAJ:Stock

Leak Jet:Stock

Starter Jet:Stock

Fuel screw (turns out):MSR 1.75 out

Needle Model/Clip position:JD red/4th

Grey Wire Mod (Y/N):Y

TPS Connected (Y/N):Y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N):Y

Airfilter Brand:Twin air

Exhaust Brand:'07 YZ header/ White Bros. E2 muffler

Average Altitude:sea level to 6500ft

Average Temperature:55-100 degrees F

Average Humidity: Across the board

Degree of Satisfaction (0-10):So far 12/10!

Shes unleased now. Everything that everybody says about the WR 450f with an aftermarket exhaust is true. I'm super stoked

Year:2002

Model (400 - 426 - 450):426

Cam Timing (WR/YZ):WR

Main jet:170

Pilot Jet: 45

PAJ:Stock

Leak Jet:N/A

Starter Jet:Stock

Fuel screw (turns out):1.75

Needle Model/Clip position:JD red/5th For Summer 120 degree heat. Winter see below.

Grey Wire Mod (Y/N):Y

TPS Connected (Y/N):Y

Airbox Snorkel/Lid (on or off): Snorkel Out, Lid Modified

AIS Removed (Y/N):N?A

Airfilter Brand:Twin Air

Exhaust Brand:Stock header muffler FMF PowerCore4

Average Altitude:sea level to 2000'

Average Temperature:45-125 degrees F

Average Humidity: 5-100 Percent

Degree of Satisfaction (0-10):So far 10/10.

Additional Mods/Comments:Thick o-ring mod from the JD kit.

Come Winter I will change out to Blue Needle on 3rd clip. And see if rest of jetting will be fine where it is.

Year: 07

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 168

Pilot Jet: 48

PAJ: 110

Leak Jet: 45

Starter Jet:

Fuel screw (turns out): 1.5

Needle Model/Clip position: red/4

Grey Wire Mod (Y/N): y

TPS Connected (Y/N): y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): y

Airfilter Brand: uni

Exhaust Brand: gytr 96db performance insert, p/n gyt-5tj93-75-01:

Average Altitude: 2-4000'

Average Temperature: 80

Average Humidity: low

Degree of Satisfaction (0-10): 9.5

Additional Mods/Comments: first I installed Yamaha AIS kit and found it to be a little rich for me. Bought the JD kit and installed per instructions, thick oring mod. very happy with this setup. left the gytr main air jet and leak jet installed.

Year:2007

Model (400 - 426 - 450):450

Cam Timing (WR/YZ):WR/STOCK

Main jet:170

Pilot Jet:48

PAJ:STOCK

Leak Jet:STOCK

Starter Jet:STOCK

Fuel screw (turns out):1.50

Needle Model/Clip position:AIS NEEDLE #3

Grey Wire Mod (Y/N):YES

TPS Connected (Y/N):YES

Airbox Snorkel/Lid (on or off):OFF

AIS Removed (Y/N):YES

Airfilter Brand:TWIN AIR

Exhaust Brand:FMF FACTORY 4.1 SLIP ON

Average Altitude:1200 METERS

Average Temperature:25 CELCIUS

Average Humidity:40-60%

Degree of Satisfaction (0-10):10

Additional Mods/Comments:NOW MY BABY IS ALIVE!!!!

Year: 2007

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 165

Pilot Jet: 45

PAJ:

Leak Jet: 45

Starter Jet:

Fuel screw (turns out): 1.5

Needle Model/Clip position: Red needle 4th from top

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): Y

Airfilter Brand: Stock

Exhaust Brand: White Brothers E2 slip on

Average Altitude: 0-4000' asl

Average Temperature: 70-90

Average Humidity:

Degree of Satisfaction (0-10): 9

Additional Mods/Comments: This site helped alot for jetting purposes. No bogs, starts first kick.

Model: 2006 WR450F

Cam Timing: WR (stock)

Main Jet: 168 (165 is stock)

Pilot Jet: 48 (45 is stock)

Fuel screw: GYTR - 2 out (about)

Needle model/Clip position: 4th pos on needle from GYTR AIS kit

Starter Jet: 65 (stock)

Leak Jet: 40 (50 is stock)

Airbox lid (on or off): snorkel removed, holes in side of box

AIS: GYTR AIS removal kit

Grey Wire Mod (Y/N): YES

Pipe: FMF Q w/ S.A.

Air filter: UNI Multi-Stage

Altitude where you ride: Sea level to 4000

Temperature where you ride: Varies, mostly 70s-80s(Jawbone)

Degree of Jetting satisfaction: Need to test, will report. :crazy:

Year: 1999

Model (400 - 426 - 450): 400FL

Cam Timing (WR/YZ): YZ

Main jet: 168

Pilot Jet: 45

PAJ1: 75

PAJ2: 90

Main air jet: 200

Leak Jet: N/A?

Starter Jet: 60

Fuel (pilot) screw (turns out): 1.5 (still tuning)

Needle Model/Clip position: OBDTM(stock)/4

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): OFF

AIS Removed (Y/N): N/A

Airfilter Brand: Stock

Exhaust Brand: stock YZF426

Average Altitude: 0ft

Average Temperature: 80F (27C)

Average Humidity: 70%

Degree of Satisfaction (0-10): 9

Additional Mods/Comments: Also have home made AvNow installed (1/4 and ½ open plates). Mostly stock setup, with ZipTy fuel (pilot) screw. Starts w/o choke on 2nd kick. No hesitation/bog, instant throttle response. Linear power band, no peaks or dips. No afterfire (backfire) after changing clip from position 3 to 4.

Year: 2008

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: JD 168

Pilot Jet: JD 48

PAJ: YEC AIS 110

Leak Jet: YEC AIS 45

Starter Jet:

Fuel screw (turns out): MSR 2

Needle Model/Clip position: JD red/4

Grey Wire Mod (Y/N): y

TPS Connected (Y/N): y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): y

Airfilter Brand: Stock

Exhaust Brand: Stock, unplugged

Average Altitude: SEA - 2000'

Average Temperature: 45-55 (So Far)

Average Humidity: 70%

Degree of Satisfaction (0-10): 8

Additional Mods/Comments: W/ Small JD O-ring MOD - This is a combo of the YEC AIS kit and a JD Jet Kit. Runs great, no bogs, but I only got 27.3 miles until I had to switch to reserve. Will try leaning it out a bit and update.

Year: 2007

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 168

Pilot Jet: 48

PAJ: 70 (stock)

MAJ: 110

Leak Jet: R&D power pump set at approx. 40

Starter Jet: 65 (stock)

Fuel screw (turns out): Zip-Ty 1.5

Needle Model/Clip position: JD Red 4th clip position

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Accel. Pump O-ring MOD (Y/N): Y

Airbox Snorkel/Lid (on or off): Off

AIS Removed (Y/N): Y

Airfilter Brand: Stock

Exhaust Brand: Stock w/GYTR insert

Average Altitude: 800'

Average Temperature: 80

Average Humidity: 70%

Degree of Satisfaction (0-10): 9.5

Additional Mods/Comments: R&D power pump is great for fine tuning the leak jet to get rid of that off-idle bog and just needs slight adjustments for Summer vs. Winter operation!

Year: 2008

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): wr

Main jet: 168

Pilot Jet: 45

PAJ: 110

Leak Jet: 50

Starter Jet: 68

Fuel screw (turns out): stock 1.5

Needle Model/Clip position: GYTR AIS 4

Grey Wire Mod (Y/N): y

TPS Connected (Y/N): y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): y

Airfilter Brand: stock

Exhaust Brand: stock pea shooter removed

Average Altitude: 4000 to 6000 ft

Average Temperature: mid 50's right now

Average Humidity: 20-30%

Degree of Satisfaction (0-10):9

Additional Mods/Comments: still have a slight hesitation off idle, but have barely done a short break-in ride.

Year:2000

Model (400 - 426 - 450):400

Cam Timing (WR/YZ):YZ

Main jet:178

Pilot Jet:48

PAJ:75

Leak Jet:

Starter Jet:65

Fuel screw (turns out):1 1/4

Needle Model/Clip position:stk needle, 3rd position

Grey Wire Mod (Y/N):Y

TPS Connected (Y/N):Y

Airbox Snorkel/Lid (on or off):off

AIS Removed (Y/N):N/A

Airfilter Brand:UNI

Exhaust Brand:stk with baffle removed

Average Altitude:1000-4000

Average Temperature:50-70

Average Humidity:

Degree of Satisfaction (0-10):9

Additional Mods/Comments:homemade power now. runs great, no bog, instant response, starts 1-2 kicks everytime

Year: 2007

Model (400 - 426 - 450): WR450

Cam Timing (WR/YZ): WR

Main jet: 168

Pilot Jet: 48

Leak Jet: Set at 40 (R&D Power Pump with ALJ)

Starter Jet: 65 (Stock)

Fuel screw (turns out): GYTR Fuel Screw 2 Turns Out (still tuning)

Needle Model/Clip position: JD Red / 4th Position

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): Off

AIS Removed (Y/N): Y

Airfilter Brand: Uni

Exhaust Brand: Dr. D Full Race

Average Altitude: Sea Level

Average Temperature: 80 - 90 F

Degree of Satisfaction (0-10): Will be testing this weekend

Additional Mods/Comments: R & D stiffer spring installed on AP linkage arm.

Model (400 - 426 - 450): 2007 WR450

Timing (WR-YZ): WR

Main jet: 165

Pilot Jet: 45

Fuel screw (turns out): ZipTy - 1.5 out

Needle model/Clip position: JD red 4

Airbox lid (off): snorkel removed

Pipe: Stock header, FMF Q4

air filter: Stock

Altitude where you ride: 2500 - 5,500 ASL

Temperature where you ride: ~50 - 85 degrees.

Degree of satisfaction 9.9

Year: 2007

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): wr

Main jet: 168

Pilot Jet: 48

All other jets from the GYTR AIS kit installed

Fuel screw (turns out): Zip TY 1.5

Needle Model/Clip position: GYTR AIS 4

Grey Wire Mod (Y/N): y

TPS Connected (Y/N): y

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): y

Airfilter Brand: stock

Exhaust Brand: stock pea shooter removed

Average Altitude: 0-500ft

Average Temperature: 70-90, but 50 right now

Degree of Satisfaction (0-10):9

Additional Mods/Comments: O-ring'd the AP arm linkage too. No off idle hesitation, a little popping here and there at 1/2 to 3/4 throttle, couple twists would clean it up. Didn't seem to have any related power loss. Have only put on about 40 miles so far. Very happy with overall performance and rideability.

Year:2001

Model (400 - 426 - 450):wr426

Cam Timing (WR/YZ):yz

Main jet:168

Pilot Jet:62

PAJ:60

MAJ:200

Leak Jet:stock

Starter Jet:stock

Fuel screw (turns out):2 1/2 turns out

Needle Model/Clip position:jd blue 2nd clip from top

Grey Wire Mod (Y/N):n

TPS Connected (Y/N):y

Airbox Snorkel/Lid (on or off):off

AIS Removed (Y/N):y

Airfilter Brand:twin air

Exhaust Brand:dr.d full stepped system

Average Altitude:1000m above sea level

Average Temperature:20c

Average Humidity:50-70%

Degree of Satisfaction (0-10):10

Additional Mods/Comments:wisco 13.5:1 comp piston, port an polished head,full dr.d exahust system, alot of bling added to carb. these mods made the bike come to life.:thumbsup:

Re: JETTING D-Base WR400/426/450

Year: 2005

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 170

Pilot Jet: 48

PAJ: stock

Leak Jet: plugged

Starter Jet: 75

Fuel screw (turns out): Pro Circuit 1.5 - 2

Needle Model/Clip position: Stock 2005 YZ NFLR middle clip (up or down 4)

TPS Connected (Y/N): Yes

Grey Wire Mod (Y/N): Yes

Airbox Snorkel/Lid (On/Off): Off

AIS Removed (Y/N): Yes

Airfilter Brand: UNI

Exhaust Brand: Stock 2005 YZ450

Average Altitude: 350 - 1000

Average Temperature: 75

Average Humidity: 45%

Degree of Satisfaction (0-10): 10

Additional Mods/Comments:

I live in Western KY. This should work in the News Channel 6 viewing area. I'm also using Sunco 110 because I keep getting bad gas from all the gas stations in town. It will rip. I plugged the leak jet with a ball I cut off of a pull-chain from a lamp. Drop it in a screw the leak jet in. It sticks up but does affect anything. I also have the AP set to where when the throttle is wide open, the rod is at the bottom with maybe a sheet of papers thickness between the screw and plastic piece on the AP.

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