2006-07 YZ450F User Jetting Database

35 replies to this topic
  • rtgincnm

Posted June 24, 2007 - 12:10 PM


I have a new '07 YZ450 just past break-in, stock pipe and airfilter
Altitide: 7500 FT
Temp: 50-75F
Main: 158 (stock was 160)
Pilot: 45 stock
Needle: stock

Check the plug after 1 to 2 hours of 2-track and it is very light in the center and dark around the outer rim. Runs great, some backfire on decel, no noticable flat spot.

Changed Pilot to 38, was 45.
Fuel Screw: 2 turn out

Runs good, starts good. at 7500 ft ASL

  • CO_Rider

Posted July 13, 2007 - 11:56 PM


Bike: 07 YZ450
Main Jet: 155 (Stock is 160) But I think was still a little lean so went to 158 and will ride tommorrow
Pilot Jet: 42 (Stock is 45)
Starter Jet: stock
Needle: Stock and 4th clip down which is stock (I raised the clip but ran bad and was a real pain to start so I went back to stock)
Leak: stock
Air box: Stock
Pipe/muffler: Stock
Altitude: 6k to about 9500
Temp: Mid 70's to 80's

  • dwnlowx

Posted September 29, 2007 - 09:11 PM


2007 yz 450

Model: 2007 YZ450f
Main Jet: 165
Pilot Jet:50
Starter Jet: stock
Leak: 55
Fuel screw: Zyp Ty 2 1/2 turns out
Needle: #3 clip ( stock)
Air box: moose
Pipe/muffler: white brothers pro
Temp:current 55-70
ELEVATION: 3500-7000
the bike runs great on u-4 gas or 110 but runs terrible on pump gas

the bike starts first kick hot or cold

  • motoman063

Posted October 13, 2007 - 03:19 PM


I have a 07 yz 450 that was very lean from the factory
I ended up with a 165 main, 42 pilot, 55 leak, and a nfpp needle 4th positon
1-1/2-2 turns on the fuel screw
I have dr.d exhast at sea level.

The bike runs clean from bottom to top

  • wes782

Posted January 22, 2008 - 01:47 PM


Bike: 07 YZ450
Main Jet: 168
Pilot Jet: 48
Starter Jet: stock
Needle: Stock
Leak: stock
Air box: uni filter
fuel screw 2
has zip ty carb mod
Pipe/muffler: Stock
Altitude: 800
Temp: in door right now 65ish? summer 80s-upper 90s

do you guys think ill need to change something for the summer? maybe 45/165?

  • DBMX 925

Posted March 19, 2008 - 09:19 AM


I have a 2006 YZ450 I did the 48 pilot 170 main stock needle .............. wow it's a new bike. Started easier and ran up and down the street crazy fast. I can't wait to get out with it. It's alot easier to jet with all the help from you guys on TT. I'm at about 250' here. Thanks for posting up all the info guys.

  • humpness

Posted June 25, 2008 - 07:41 PM


2007 yzf450
48 pilot
165 main
needle stock
leak jet stock
1 1/2-2 1/2 turns fuel screw

  • grayracer513

Posted September 22, 2008 - 08:06 PM


READ BEFORE POSTING!: This thread is intended to be used as a reference collection of jetting used by members ONLY. Please use the provided template below, and post only the jetting you currently use, along with any pertinent comments. Post only in the correct thread for your model bike.

DO NOT ask questions or discuss the information posted here in this forum. If you want to talk about anything here, please do so in a new or current thread on the topic and use a link to the particular post you wish to discuss. Posts not complying with this format will be removed without comment.

NOTICE:The people who post here are of all skill levels. This information is only intended to let you see what others are using, and cannot be taken to mean that the information is accurate, will apply to your use correctly, or even that the poster's bike runs right with the posted setup. Use it as a guide/starting point only, and look at as many relevant postings as you can before proceeding.


Post your jetting using the template below (copy and paste to your post) and please be as complete as you can. In the Comments section please include any modifications you feel will have a bearing on the jetting, such as cams, accelerator pump mods, bored carbs, etc.


Edit Revision Date:
Main Jet:
Pilot Jet:
Starter Jet:
Leak Jet (if any):
Fuel screw/Setting:
Altitude Range:
Temp Range:
Humidity Range:



OEM 2006 YZ450F(V) Jetting:

Main Jet: 165
Pilot Jet: 42
Starter Jet: 72
Leak Jet (if any): 55
Fuel screw/Setting: 2.125-2.5 turns out
Needle/Position: NFPR-4

OEM 2007 YZ450F(W) Jetting:

Main Jet: 160
Pilot Jet: 45
Starter Jet: 72
Leak Jet (if any): 55
Fuel screw/Setting: 1.25-1.75 turns out
Needle/Position: NFLR-4

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  • WGP

Posted September 23, 2008 - 08:04 AM


Model:2006 YZ450
Edit Revision Date: 9/08
Main Jet:168
Pilot Jet:48
Starter Jet:Stock
Leak Jet (if any):40
Fuel screw/Setting:1.25 Out
Needle/Position: JD Red #5
Pipe/muffler:FMF Ti Powercore
Altitude Range:4000-8000'
Temp Range:40-90 F
Humidity Range:5%-20%

Comments: Starts easily and crisp throttle response. Very little backfiring, usually only happens when going down a steep hill and using hard engine braking.:excuseme:

  • qwik12beat

Posted December 22, 2008 - 04:14 PM


Model:2007 YZ450F
Main jet: 170
Pilot jet:48
Fuel screw: 2 1/8 out
Starter jet:stock
Leak jet:42

O-ring mod,shortened stock exhaust 3",93octaneBP,Powerflow air filter cage and filter. Bike is awesome. Great throttle response.Pulls hard. No flat spots. Starts easy. No pop on decel.

  • yz400fdude

Posted February 15, 2009 - 09:32 PM


Model: '07 yz450f
Main Jet: 168
Pilot Jet: 48
Starter Jet: stock
Leak Jet (if any): stock
Fuel screw/Setting: 2 1/4
Needle/Position: 4th
Filter: stock
Pipe/muffler: stock
Altitude Range: 400-1000
Temp Range: 40-90
Humidity Range:

Little popping under heavy engine braking, otherwise no popping. Still feels a tad rich, need to play with the fuel screw some more.

  • geshields

Posted February 28, 2009 - 06:35 AM


Model: 2007 YZ450F
Edit Revision Date:
Main Jet: 165(Stock)
Pilot Jet: 45(Stock)
Starter Jet: Stock
Leak Jet (if any): Stock
Fuel screw/Setting: 1 1/2 turn out
Needle/Position: Stock
Filter: Twin Air
Pipe/muffler: DR. D Stainless w/spark arrestor installed
Altitude Range: 100-300ft
Temp Range: 60-85F
Humidity Range: 70-95%

Comments: O-Ring mod done to Accelerator Pump. No Bog. Runs perfect and keeps on pulling...

  • bullpen58

Posted April 13, 2009 - 09:48 PM


Model: 2006 YZ450F
Edit Revision Date: 4/12/09
Main Jet: 170
Pilot Jet: 48
Starter Jet: Stock
Leak Jet (if any): Stock
Fuel screw/Setting: Zip Ty Racing, 2.75 out
Needle/Position: Stock
Filter: Ready Racing
Pipe/muffler: Stock
Mods: Boyesen Quick Shot (first gen)
Altitude Range: 50 - 300
Temp Range: 60 - 80 F
Humidity Range: Unknown

Comments: Thanks to the info posted in here, I finally got my bike to (mostly) quit back firing on deceleration. Of course, I'm still too far out on the fuel screw but that's the only way to get it to almost quit. I may try one size larger on the main and pilot to see if I can turn the fuel screw in a bit. I have no idea the ramifications for running the fuel screw too far out but I've been running it over 3 out for years now. hehe. Didn't have any major problems from doing that but it was obviously not jetted right.

I tried the 48 pilot without changing the main one time (years ago) and the bike would NOT start. Then, I ran the 45 pilot with stock everything else (besides the Quick Shot) and it ran okay . . . I thought.

But when I tried the 170 main with the 48 pilot it fired right up like it always has (which was more important to me than the back firing). With this new setting, the back firing is almost gone completely and the power does seem to come on a little stronger earlier and stay stronger for longer in the RPM range. I only rode it up and down a mostly flat road a few times so I have yet to test it on a track.

I'm super optimistic that I made the right changes and may post a follow-up about it later this month.

  • saca

Posted April 23, 2009 - 07:17 PM


Main jet: #165s

Pilot jet: #45

Needle jet: Nincs

Starter jet: #72

Pilot air jet: #100

Leak jet: #55

Jet needle: #NFPR #4

Standard pilot screw position : 2 1/8 out

Altitude 0-300ft

  • jrny426

Posted May 17, 2009 - 09:05 AM


07 450
3000- 5000ft
Main 165
Pilot 42
Needle was 4 now 5
Sunline Fuel Screw 2 turns out

Works great for trail riding at alltitude Good power bottom thru top

  • icon27

Posted October 18, 2014 - 03:49 PM


Model: 2007 Yamaha YZ 450f
Edit Revision Date:
Main Jet: 160
Pilot Jet: 45
Starter Jet: stock
Leak Jet (if any): stock
Fuel screw/Setting: 1 3/4
Needle/Position: stock/3
Filter: twin air
Pipe/muffler: stock
Altitude Range: 5290
Temp Range: 70
Humidity Range: 46%

Comments: still running very lean. Quite a bit of backfire on deceleration. 0 to 1/4 throttle gasping for air. Seems that 1/4 to 3/4 throttle feels like it is getting better. I need help!! I'm one crappy day from going Fuel injection.

Attached Thumbnails

  • image.jpg

Edited by icon27, October 18, 2014 - 03:59 PM.

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