2009 WR450 Jetting Help for Colorado 6,500 - 9,500ft

Posted this in the Intake/Jetting area too, but wanted to get some feedback from those that don't frequent that thread:

Purchased an '09 WR450 used and need help dialing in the jetting...here's the skinny of what it's got, doesn't seem right:

1)2009 WR450

2)conditions (Colorado) (6,500 - 9,500', 50-75 degrees, low humidity, trail riding

3)modifications (FMF Q4 with powerbomb header, stock air box, stock motor with AIS removed)

4)current jetting:

- Main 168

- Pilot 50

- Starter 65

- Leak 45

- Needle GDDTR 4th clip from top

5)running issue - hesitation at 1/4 - 3/4 throttle position, black soot on pipe and plug, burn mark on pipe (sticker burned)

6) Running issue unchagned? affected by motor temp (NO)? better or worse when hot (NO)? better or worse when cold (NO)?

Your WAY to fat on the main jet. I run a 152 main for the same altitudes.... see what I have on the bottom of my post and you'll get the idea.

Year: 2008

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 152 (yes, a 152!)

Pilot Jet: STOCK


Leak Jet: STOCK

Starter Jet: STOCK

Fuel screw (turns out): 1.5 on R&D Adjustable


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: FMF POWERCORE 4

Average Altitude: 5000-14,000ft

Average Temperature: 50-80F

Average Humidity: Pretty darn DRY!

Degree of Satisfaction (0-10): 9.5

Edited by Mtn-Track

For those of you in the same area that want to know...here's what I did that worked great:

Ordered the JD jetting kit:

Year: 2009

Model (400 - 426 - 450): 450

Cam Timing (WR/YZ): WR

Main jet: 160

Pilot Jet: 48


Leak Jet: 45

Starter Jet: 65

Fuel screw (turns out): 2-1/4 Zip-Ty

Needle Model/Clip position: JD Needle Red - 3rd clip from top

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y

Airbox Snorkel/Lid (on or off): ON

AIS Removed (Y/N): Y

Airfilter Brand: STOCK

Exhaust Brand: FMF Q4 with Powerbomb header

Average Altitude: 7,000-11,000ft

Average Temperature: 50-80F

Average Humidity: low

Degree of Satisfaction (0-10): 9

Glad to hear you got it working well! The "JD" jet kit helps considerably! I'm sure that other methods work equally well, but having the JD jetting chart takes a lot of guess-work out of the equation!!!


You need a 155 main, but you are close otherwise. All you needed was a $6 pilot and $6 main jet.

Spoke too soon...rode 50 miles of trails yesterday at 9-10,000ft and has a pretty significant off idle bog and after washing the bike today it's back firing pretty significantly on decel.

Try a 45 pilot at 1.75 turns out on the fuel screw, or with the 48 you have in it now, turn it down to 1.5 turns. A leaner main, like a 155, will help, but that wasn't responsible for your off-idle bog. You were drowning it in fuel.

Decel popping isn't always bad jetting.

Edited by Leardriver

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