2003-05 YZ450F User Jetting Database

23 replies to this topic
  • slothman

Posted December 14, 2012 - 04:23 PM


Model: 05 YZ450F
Main Jet: 165
Pilot Jet: 52
Starter Jet: stock
Leak Jet (if any):
Fuel screw/Setting:
Needle/Position: #5 from the top
Filter: Uni
Pipe/muffler: Bills exhaust header & pro billet muffler
Altitude Range: 200-2500
Temp Range: 40-70
Humidity Range:

  • smokingtz

Posted June 26, 2013 - 07:04 PM


[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Model: 03 YZ450F[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Edit Revision Date: 6/26/13[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Main Jet: stock[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Pilot Jet: stock[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Starter Jet: stock[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Leak Jet (if any):[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Fuel screw/Setting: stock[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Needle/Position: unknown[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Filter: stock foam[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Pipe/muffler: stock[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Altitude Range: 0[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Temp Range: 40's to 90[/background][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Humidity Range: 0 to 100%[/background][/font][/color]

[color=#282828][font=helvetica, arial, sans-serif][background=rgb(252, 252, 252)]Comments: Ran perfectly since new. Never felt the need to mess with it. No popping. Starts fine. Runs stronger around 40 degrees. My 03 WR250F was another story.[/background][/font][/color]

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • bluthndr

Posted September 19, 2013 - 05:10 AM


Model: 03 YZ450F
Edit Revision Date: 9/19/13
Main Jet: 175
Pilot Jet: 50
Starter Jet: 72
Leak Jet (if any):
Fuel screw/Setting: Moose(?) 2.5 turns out
Needle/Position: unknown
Filter: stock foam
Pipe/muffler: C4M full exhaust with header
Altitude Range: 600'
Temp Range: 60- 80's
Humidity Range:

Comments: Should be rich by the numbers, but actually runs great.  Finally tuned to where it will start good hot and cold, crisp throttle response, hot-start lever needed when hot (this is a first).  Unknown history of the bike means it may have cams and/or a big bore kit, but I don't know how to tell.  Seems to have more power than my friends' newer YZ450Fs (05, 06, 09)...

Edited by bluthndr, September 19, 2013 - 05:11 AM.

  • dattorob

Posted December 02, 2014 - 09:40 PM


Model: 05 YZ450F
Edit Revision Date: 03-12-2014
Main Jet: 168
Pilot Jet: 50
Starter Jet: 72
Leak Jet (if any): unsure (have powerbowl)
Fuel screw/Setting: 2 turns out
Needle/Position: NFLR , 2nd position
Filter: uni
Pipe/muffler: FMF Ti power core muffler, some custom ti midpipe and header
Altitude Range: 300ft
Temp Range: 60-100 F

Humidity Range: 25-50%

Comments: big bore kit (480cc), power bowl on carb, cams and porting (unknown), standard air-intake. Starting is not that great, hesitant/rough in mid throttle. 


Related Content


100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

Is the 2016 GYTR Yamaha YZ450F too fast? by Fryboy

Dirt Bike   Special Interest Forums   Pro Racing
  • * - - - -
  • Hot  241 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  35 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.