Robert_Brazil

WR400/426/450 Jetting Database

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WR400/WR426/WR450 Jetting Database Instructions

The purpose of this thread is to provide a comprehensive database for jetting the various models of the WR. It is not intended as a thread to directly solicit or offer help and/or advice. In other words, "Just the facts, Ma'am"

When posting to this thread, please use the following format:

Year:

Model (400 - 426 - 450):

Cam Timing (WR/YZ):

Main jet:

Pilot Jet:

PAJ:

Leak Jet:

Starter Jet:

Fuel screw (turns out):

Needle Model/Clip position:

Grey Wire Mod (Y/N):

TPS Connected (Y/N):

Airbox Snorkel/Lid (on or off):

AIS Removed (Y/N):

Airfilter Brand:

Exhaust Brand:

Average Altitude:

Average Temperature:

Average Humidity:

Degree of Satisfaction (0-10):

Additional Mods/Comments:

In an effort to keep the database streamlined and uncluttered, conversational posts will be deleted. If you need to update your settings, send me your changes via PM and I'll enter them for you so we don't get duplicates. Thanks for your help :) ...SC

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Model (400 - 426 - 450): 2005 WR450

Timing (WR-YZ): WR

Main jet: 168

Pilot Jet: Stock, 45?

Fuel screw (turns out): ZipTy - 2 out

Needle model/Clip position: JD Blue #3

Airbox lid (on or off): snorkel removed

Pipe: Stock, baffle completely removed

air filter: Stock

Altitude where you ride: 2500 - 4000 ASL

Temperature where you ride: ~50 - 60 degrees now.

Degree of satisfaction :)

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Here is what works for me and you guys can use it as a starting point to jet your WR450 bikes only! :)

(Note: do not use these for WR426 or WR400 due to carb differences!) :)

This recommendation requires air box flow mods and an open stock or aftermarket pipe and ACV circuit intact. :p

Elevation 0 to 4,000. feet

30 to 45 degrees: 172 main, JD Blue #5, 48 Pilot, 2.0 turns, 75 starter jet, #0 leak jet

45 to 60 degrees: 170 main, JD Blue #4, 48 Pilot, 1.75 turns, 72 starter jet, #0 leak jet

60 to 75 degrees: 168 main, JD Blue #3 or JD Red #5, 48 Pilot, 1.5 turns, 70 starter jet, #40 leak jet

75 to 90 degrees: 165 main, JD Red #5, 48 Pilot, 1.25 turns, 68 starter jet, #50 leak jet

90 degrees plus: 160 main, JD Red #4, 45 Pilot, 2.0 turns, 65 starter jet, #60 leak jet

Elevation 4,000 to 8,000 feet:

30 to 45 degrees: 170 main, JD Blue #4, 48 Pilot, 1.75 turns, 72 starter jet, #0 leak jet

45 to 60 degrees: 168 main, JD Blue #3, 48 Pilot, 1.5 turns, 70 starter jet, #40 leak jet

60 to 75 degrees: 165 main, JD Red #5, 48 Pilot, 1.25 turns, 68 starter jet, #40 leak jet

75 to 90 degrees: 165 main, JD Red #5, 45 Pilot, 2.0 turns, 65 starter jet, #50 leak jet

90 degrees plus: 160 main, JD Red #4, 45 Pilot, 1.75 turns, 65 starter jet, #60 leak jet

Elevation 8,000 to 11,000 feet: ( Note you will loose a lot of power due to altitude but your bike will idle and not foul plugs!)

45 to 60 degrees: 165 main, JD Red #5, 48 Pilot, 1.25 turns, 70 starter jet, #40 leak jet

60 to 75 degrees: 160 main, JD Red #4 , 45 Pilot, 1.75 turns, 68 starter jet, #50 leak jet

75 to 90 degrees: 158 main, JD Red #3, 45 Pilot, 1.5 turns, 65 starter jet, #60 leak jet

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Model: 2005 WR450

Timing: WR

Main Jet: 170

Pilot Jet:Stock 45 drilled to 48

Starter Jet: 75

Leak: stock #50

Fuel screw: Zyp Ty 1 3/4 turns out

Needle: JD red 4th clip

Air box: snorkle removed and tray cut open

Pipe: Stock with baffled removed

Altitude: 0-2000K

Temp:current 45-80F

Humidity: 50-60%

Degree of statifaction: bike is great,no bog, good throttle response(need to drecrease leak jet to Indy's idea of zero)

Note: the weather here is about to drastically change to over 100F and the humidity will drop to single digits. All this jetting will change!!!!!!!!!

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Year: 2005

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 168

Pilot Jet: 45

PAJ: 80

Leak Jet: 42

Starter Jet: 70

Fuel screw (turns out): Zip-TY 1.5

Needle Model/Clip position: JD Blue #3

TPS Connected (Y/N): Yes

Grey Wire Mod (Y/N): Yes

Airbox Snorkel/Lid (On/Off): Snorkle-ectomy w/ Airbox Knockouts + PowerNow

AIS Removed (Y/N): Yes

Airfilter Brand: Twin Air

Exhaust Brand: DR.D SA w/ FMF SX Powerbomb

Average Altitude: 4500-6000

Average Temperature: 40°-50°F

Average Humidity: 45%

Degree of Satisfaction (0-10): 10

Additional Mods/Comments:

13/49 Ironman Sprocket Set

Fun Factor: 11 Bananas... :):D:D:D:thumbsup::):p:D:D:o;)

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Model (400 - 426 - 450):'03 WR450

Timing (WR-YZ):WR

Main jet:168

Pilot Jet:48

Leak Jet:40

Pilot Air Jet:100

Fuel screw (turns out):1-1/4-1-3/4

Needle model/Clip position:JD Blue #4

Airbox lid (on or off):On-snorkle out

Pipe:Thunder Alley ceramic coated w/SA

Altitude where you ride:800-4000ft

Temperature where you ride:70 deg. ideal for these settings

Degree of satisfaction: :):)

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Model (400 - 426 - 450): 1999 WR400F

Timing (WR-YZ): WR

Main jet: 172

Pilot Jet: Stock, 45

Fuel screw (turns out): ZipTy - 2 out

Needle model/Clip position: Stock

Airbox lid (on or off): snorkel removed

Pipe: White Brothers E-series

air filter: Twin Air

Altitude where you ride: 2500 - 5500 ASL

Temperature where you ride: ~40 - 70 degrees now.

Accelerator Pump Cover: Factory R&D P-38

Degree of satisfaction: Runs well. Still dialing it in. Crisp response, may be a bit rich.

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Model (400 - 426 - 450): '02 426

Timing (WR-YZ): WR

Main jet: 170

Main air jet: 200

Pilot Jet: 45

Pilot air jet: 100 PAS

Fuel screw (turns out): 1 1/3

Starter jet: 72

Leak jet: N/A

Needle model/Clip position: EMN/4

Airbox lid (on or off): OFF

Pipe: Jardine RT-4

Altitude where you ride: 400 Ft

Temperature where you ride: 70-80 F (now)

Humidity: 50-60% (now)

Degree of satisfaction: :)

Others: BK mod (0.9mm gap), Power Now (home made), ACV disabled, AP cover mod (home made Boyesen )

Comments: NO bog, sputter, flat spot, popping or backfire

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Model : '05 WR450

Timing (WR-YZ): Stock WR - Gray wire pulled

Main jet: 170

Pilot Jet: Stock

Fuel screw (turns out): Zip-Ty 1.75

Needle model/Clip position: JD Red #4

Airbox lid (on or off): On

AIS: Gone

Pipe: Stock w/PMB insert

Altitude where you ride: 500'

Temperature where you ride: 100 degrees

Degree of satisfaction: 10

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Model- 2005 WR 450

Timing-WR with grey wire pulled

MJ-168

PJ-48

LJ- stock

Needle- JD Blue, #3 Position(Winter, So Cal Deserts) JD Red Needle #5 Position (Spring, Summer, So Cal Deserts)

R&D P-38 accelerator pump cover

Air snorkel- removed

Fuel screw- Zip-Ty 1 1/2 to 1 3/4

Exhaust - Stock with baffle removed and PMB insert.

Elevation- 500 to 2000 feet above sea level

Temp- 60's to 80's

Degree of satisfaction- I'm dialed in and stoked!!!!! :naughty:

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Model: 2005 WR450f US model

Cam Timing: WR (stock)

Main Jet: 170

Pilot Jet: 48

Fuel screw: MSR Hard Parts - 2 out (about)

Needle model/Clip position: 04 WR 4th pos

Starter Jet: 70

Leak Jet: 40 (50 is stock)

Accelerator pump cover: Factory R&D "Lightning"

Airbox lid (on or off): snorkel removed

AIS: Mark Lowe's Smog removal kit

Pipe: Yamaha GYT-R Aluminum slip-on Quiet cap

Air filter: UNI-This filter is a work of art!

Altitude where you ride: Sea level to 4000

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

Degree of Jetting satisfaction: 10 :naughty:

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Model (400 - 426 - 450): 03 WR450 European model

Timing (WR-YZ): WR No grey wire on EU model

Main jet: #160

Pilot Jet: #48

Fuel screw (turns out): 1.25

Needle model/Clip position: OBDUQ-4

Airbox lid (on or off): No snorkel lid still on!!? Holes cut above rear mudguard(fender)

Pipe: FMF PC4 with SA and quiet insert

Altitude where you ride: 0- 2000ft

Temperature where you ride: 15 to 45 degC

Degree of satisfaction: :naughty::naughty::D

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Model (400 - 426 - 450): 03' WR 450 Aust model

Timing (WR-YZ): WR

Main jet: #160

Pilot Jet: # 45 (#48 Std)

Fuel screw (turns out): 1 1/2

Leak Jet: # 40 (#50 Std)

Needle model/Clip position: JD Red / pos 5

Airbox lid (on or off): off snorkel removed 2x45mm holes drilled

Pipe: Stock w/screen removed

Altitude where you ride: 0-1000ft

Temperature where you ride: 90deg+ 70%-90% humidity

Degree of satisfaction: 8/10

I think a pipe would help and now I see the thread for the Acc pump cover, looks like my satisfaction rating will go up with that puppy if I can find one. I like techo hills, so I'd say this mods for me.

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Model (400 - 426 - 450): 2003 WR450F

Timing (WR-YZ): YZ

Main jet: 162

Pilot Jet: 50

Fuel screw (turns out): 1 3/4

Needle model/Clip position: 4th

Airbox lid (on or off): off

Pipe: Yoshimura Off-Road Slip on (very loud)

Altitude where you ride: 2000-7000ft

Temperature where you ride: 45-90

Degree of satisfaction: Very

My e-button would never work until I performed these changes...I love this bike finally, and it never backfires! :naughty:

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Model WR400 1999...acv removed..snorkle removed..grey wire cut..WB E-2..

YZ450 Cam..elevation 0 to 7000 feet..80 degrees F+

EKN needle clip 3 or JD blue clip three year round w/ fuel screw adj. only..

160mj

160 maj

40pj

75paj

70sj

.5 apj taffy mod

FS 1 to 1.5 turns

2005 WR450..WR timing..grey wire cut..air box mod..PMB exhaust insert. Zip-ty FS..0-7000 feet..40 to 90 degrees F..acv intact

JD Red clip5

170 mj

200 maj

45 pj winter 48pj

75 paj

65 sj winter 72sj

50 leak jet

FS 1.5 to 2.0

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Model: '01 WR426

Timing:YZ

Main jet: 162

Pilot Jet: 40

Fuel screw (turns out): 2

Needle model/Clip position: 2

Airbox lid: off

Pipe: FMF Powercore 4 II

Altitude where you ride: 5,000-9,500

Temperature where you ride: lets say 50-75...although 32-90 at times.

Degree of satisfaction: :naughty:

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Model (400 - 426 - 450): 05' WR 450F

Timing (WR-YZ): WR

Main jet: #170

Pilot Jet: # 48 (#48 Std)

Fuel screw (turns out): 1 3/4

Leak Jet: # 40

Needle model/Clip position: JD Red / pos 5

Airbox lid (on or off): off snorkel removed 2x45mm holes drilled

Pipe: White Brothers E2

Altitude where you ride: 0-3000ft

Temperature where you ride: 65-90deg

Degree of satisfaction: 9/10

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'05 WR450F

JD blue needle #3

170mj

The rest is stock. All of the free mods done, plus AIS block off kit. I've had zero problems since installing his kit. The only things I've had to change were the clip position (#4 down to #3) and dropped the mj from 170 to 168. I'm just above sea level, and the bike runs GREAT!!! :naughty:

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I sold my bike to BrandonW but I had the LarryCo Jetting

Model 2001 WR426:

Timing YZ timed, WR timing required no change in jetting

Main jet: 155

Pilot Jet: 38

Pilot Air Jet: 65 Adjustable from Sudco

Fuel screw: 2 Turns out

Needle model/Clip position: EKP #3 Position

Airbox lid: Off

Pipe: FMF Q or Stock Open

Altitude where you ride: 5,000'-13,000'+

Temperature where you ride: 30F-95F

Degree of satisfaction: 9+ out of 10

Other:

BK Mod with Screw and nut, timed to 1/3-1/2 second.

Grey wire unplugged

Throttle Stop Cut

152 main for 10,000+ Feet

160 main for Moab which is around 4500 feet

If using a PMB or GYRT insert, I had both.

148 main for 10,000 feet

152 main for all other Colorado riding

155 main for Moab

My bike ran great like this and all I had to change for altitude was the main. I had fouled tons of plugs with the original jetting and this solved my problem completely. LarryCo did a ton of work on this jetting with the help of Taffy. I was just lucky enough to come in after they finished. :naughty:

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Model (400 - 426 - 450): 1999 WR400F

Timing (WR-YZ): WR

Main jet: 170

Pilot Jet: Stock, 45

Fuel screw (turns out): 2 out

Needle model/Clip position: JD red on the 4th groove

Airbox lid (on or off): snorkel removed

Pipe: FMF Powercore 4

air filter: stock

Altitude where you ride: 0 - 500 ASL

Temperature where you ride: ~60 - 70 degrees now.

Accelerator Pump Cover: stock with an after market diaphragm w/longer stud (squirts sooner)

Degree of satisfaction: Runs great! I snipped the gray wire, shortened the throttle stop, added a JD needle and a quicker shooting diaphragm for snappy no bog acceleration...The biggest improvement came after the JD triple taper needle, this bike rips now! Thanx JD

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