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MotoGoalie

2003-05 YZ450F User Jetting Database

24 posts in this topic

Since the bikes are somewhat mechanically similar here is a link to the WR guys; though we need you guys to put your info in too for the YZF ya know. :naughty:

http://www.thumpertalk.com/forum/showthread.php?t=230021

Model: 2003 YZ450f

Edit Revision:12/12/05

Timing:

Main Jet: 158

Pilot Jet:38 (edited)

Starter Jet: stock?

Leak: n/a

Fuel screw: Zyp Ty 1 1/2 turns out

Needle: #3 clip ( stock)

Air box: Twin Air and Unis

Pipe/muffler: Stock header, FMF Q (older version)

Altitude: 5700 feet and up to 11k

Temp:current 40-80F

Humidity: 30%

After Edit Satisfaction: Bike runs perfectly now. Lesson learned is that a very rich pilot and a very rich main jet seems to mimick a lean condition. High hanging idle, surging and sometimes hard to start. Except it could foul a plug.

Pre-edit, I'm on the verge of dropping the needle back down, ie placing the clip at the #4 position, back in the middle position to richen it up slightly.

#4 position at 8000 feet and 80'f was horrible, creating a rich bog in the middle and stumbling from 1/4 to 3/4 throttle. Probably because needle richness in conjunction with AP injection. #3 needle clip is best setting

I love the Q by the way. Its sufficiently quiet that you can now hear a lot of engine noise. Man these motors rattle and hum :naughty:

Degree of statifaction prior to the 38 pj change which was a 42: bike is g00d,no bog, good throttle response and runs like a striped ape WFO BUT it has a real annoying midrange surge that I cannot cure either with richer or leaner jetting, needle height etc. Sometimes hard to start.

Note: Temp has ranged from 70'f to 95'f recently so everyday its something different. Altitude has ranged from 5700 to 9000 feet.

As of 11-1-05 the current jetting is perfect for my conditions. Italics denote notes prior to finding a good combination of lean needle and pj range.

http://img.photobucket.com/albums/v518/MotoGoalie/Flagshroud3.jpg

clarke 2.8, XGX graphics, Utah skid, FMF Q

& my turkeybaster overflow

http://img.photobucket.com/albums/v518/MotoGoalie/overflowtank.jpg

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Model: 2003 YZ450f

Timing: YZ

Main Jet: 155

Pilot Jet:38 Edited

Starter Jet: stock

Leak:

Fuel screw: 1 1/2 turns out

Needle: stock at #3

Air box: no lid

Pipe/muffler: gyt-r aluminum

Altitude: 7000 feet and up

Temp:current 50-90 F

Humidity: 70%

Other:

Degree of satisfaction: Slight pop/sputter at steady 1/8 - 1/2 throttle still, but soooo much better than before I moved the needle. It is now very rideable, no surge. Tried a 150 and a 160 main, but the 155 feels the best. At full throttle there is no bog and strong power from beginning to end (of course, it's a yz450f).

Degree of satisfaction after edit: motogoalie had the answer. The 38 pj made this thing run absolutely perfectly. All sputter is gone, and it purrs like a kitten. I really am not exagerating. Perfect. :)

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well i never would have thought it but;

2005 YZ450:

MJ: 160

PJ: 40

fuel:1 3/4-2 out

SJ: stock

LJ:40(stock)

needle: NDWR(04 wr450) 3rd clip (DWR needle is leaner than stock)

ALT:2k-5k

TEMP:70-90

HUM:60-70%

options; powerbomb header w/powercore 4-wide open,powernow,twin air screenless,boyesen quick shot. runs perfectly everywhere,starts great, no bog/stalling. only questionable thing is that when the hot start lever is pulled it doesn't idle up it starts to burble?

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Model: 2004 YZ450F

Timing: YZ

Main Jet: 158

Pilot Jet: 38 :)(edited)

Starter Jet: 70 (edited)

Leak: N/A

Fuel screw: 1 1/4 to 1 3/4 turns out

Needle: stock at #3 position

Air box: unmodified w/Twin Air filter

Pipe/muffler: Powerbomb SX/Powercore 4

Altitude: 5700 to 7500 feet

Temp: 75-95 F

Humidity: 30% to 50%

Other: Dr. D +6oz. flywheel

Degree of satisfaction: I jet for the track at 5750 feet. I'm generally pleased with it like this. I've gone from a #40 pilot to a #38 and the bike runs even better now. I also went from the stock #72 starter jet to #70 and it starts even more easily. It looks like my settings are pretty much the same as Motogoalie's now even with the different pipes. I haven't been out on the trail at higher altitude yet, but it looks like we ride pretty much the same weather and altitude conditions.

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The cold weather is here and I've fattened up my jetting for the cold air.

Timing: YZ

Main Jet: 160

Pilot Jet: 38 (edited from 40)

Starter Jet: 70

Leak: N/A

Fuel screw: 1 1/4 to 2 1/2 turns out

Needle: stock at #3 position

Air box: unmodified w/Twin Air filter

Pipe/muffler: Powerbomb SX/Powercore 4

Altitude: 5700 to 6200 feet

Temp: 55-65 F

Humidity: 15% to 35%

I'm happier now with theses changes versus the mid summer specs with the cold weather. Just an occasional pop when chopping the throttle, generally happening when the track is just watered. The bike feels faster in the cold weather. I can't wait to ride a 450 at sea level.

Runs better with the 38 pilot jet at 65 degrees.

Summer specs:

Model: 2004 YZ450F

Timing: YZ

Main Jet: 158

Pilot Jet: 38 :banghead:(edited)

Starter Jet: 70 (edited)

Leak: N/A

Fuel screw: 1 1/4 to 1 3/4 turns out

Needle: stock at #3 position

Air box: unmodified w/Twin Air filter

Pipe/muffler: Powerbomb SX/Powercore 4

Altitude: 5700 to 7500 feet

Temp: 75-95 F

Humidity: 30% to 50%

Other: Dr. D +6oz. flywheel

Degree of satisfaction: I jet for the track at 5750 feet. I'm generally pleased with it like this. I've gone from a #40 pilot to a #38 and the bike runs even better now. I also went from the stock #72 starter jet to #70 and it starts even more easily. It looks like my settings are pretty much the same as Motogoalie's now even with the different pipes. I haven't been out on the trail at higher altitude yet, but it looks like we ride pretty much the same weather and altitude conditions.

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2003 YZ450 with JD jetting kit at Ga weather and high humidity - Altitude 900 -2400 ft

Temps above 60 - F

Red JD needle 3rd or 4th clip

170main

stock pilot

Temps below 55 - F

Blue needle - 3rd clip

172-175main depending on temp

larger pilot

I do not ride below 45 -F period!

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Model: 2005 YZ450F

Timing: TPS and NSS disconnected

Main Jet: 170

Pilot Jet: 42

Starter Jet: OE

Leak:OE

Fuel screw: 1 1/2 to 2 turns out

Needle: stock at #3 position

Air box: Rear 1.5" trimmed off w/Twin Air filter or UNI

Pipe/muffler: WB Carbon Pro I

Altitude: 1100 to 2500 feet

Temp: 40-105 F

Humidity: 30% to 50%

Other: Head Ported, Carb done, power now front & rear u 4 fuel saftey wired accelerator pump

Degree of satisfaction: The bike is a superfast and I am pleased with it. like it is. I've gone from a #42 pilot to a #45 and back I think the U4 clogged up my pilot jet.

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Model: 2003 YZ450f

Edit Revision:12/12/05

Timing:

Main Jet: 158

Pilot Jet:38 (edited)

Starter Jet: stock?

Leak: n/a

Fuel screw: Zyp Ty 1 1/2 turns out

Needle: #3 clip ( stock)

Air box: Twin Air and Unis

Pipe/muffler: Stock header, FMF Q (older version)

Altitude: 5700 feet and up to 11k

Temp:current 40-80F

Humidity: 30%

Cut and paste this template for your bikes setup.

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Model: 2003 YZ450f

Timing:

Main Jet: 164

Pilot Jet:42

Starter Jet: stock

Leak: stock

Fuel screw: Stock 2 turns out

Needle: #4 clip stock needle

Air box: No-Toil filter and oil

Pipe/muffler: Dr.D SS with arrestor

Altitude: 4000ft-5000ft

Temp:current 80F

Humidity: dry

Bike is very strong no hesitation but very hard to start. Takes 4-5 kicks to start after it's warm. Pops on decell.

Any suggestions? I was thinking about just trying next size down pilot. WIll that help with my starting?

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Model: 2003 YZ450f

Timing:

Main Jet: 162

Pilot Jet:40

Starter Jet: stock

Leak: stock

Fuel screw: Stock 1.5 turns out

Needle: #4 clip stock needle

Air box: No-Toil filter and oil

Pipe/muffler: Dr.D SS with arrestor

Altitude: 4000ft-5000ft

Temp:current 90F

Humidity: dry

The 40 PJ seems to be about right. 38 was to lean 42 is hard to start. I went out for a weekend about 1500ft higher then where I live. Bike seemed to run slightly rich on the trails but still easy to start. However I think I can go bigger on the main (at least up to 164) I'm going to see how big is to big.

Starts within 5 kicks when cold and 1 kick there after. Only a slight pop on decell after a few seconds. I guess thats to be expected with the aftermarket exhaust.

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Just drug the 03 450 out and dusted it off....I started it up and rode down the

street and she still scares me....I have a 45 pilot and 165 main. Fuel screw is 2 turns out. needle stock position, and a E-Series pipe with 12 plates ...Runs perfect, idles, no poping....

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Bike: 05 YZ450

Main Jet: 162

Pilot Jet: 48

Starter Jet: stock

Needle: Stock

Leak: stock

Air box: Stock/ Twin Air

Pipe/muffler: Yoshimura TRC Pro Series

Altitude: 0 to 1000

Temp: Mid 60's to 80's

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03 yz450f current specs

Main Jet: 162

Pilot Jet: 42

Starter Jet: 72

Fuel Screw: 1-1.75 turns out

Leak: ?

Air box: stock box K&N filter

Pipe/muffler: big gun full no sparky

Altitude: denver 4800-5800?

Temp: summer 80-100f

as it sits it runs decent in town no real bogs/misses. 1 kick cold, sometimes 8+ hot(even with hot start) HORRENDUS popping on decel.

in the hills it has a noticble low rpm bog (thought it was fouling a plug at first....bog bog-rrrrriiiiiiiiiiiippppppppp ) but runs fair up high. still super bad popping.

gonna go 38 pj and 160 mj 70sj (motogoalie is skaking his head at me i bet for 3 changes at once) and retest.....

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Bike: 05 YZ450

Main Jet: 165

Pilot Jet: 48

Starter Jet: stock

Needle: Stock

Leak: stock

Air box: uni filter

fuel screw 1 1/2

zip ty carb mod

Pipe/muffler: GYTR stepped

Altitude: 0 - 2000

Temp: 40s to 50s

Runs good, has not bog, and plenty of power. I'll probably switch back to a 45 Pilot in the summer.

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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 ONLY INFORMATION APPLICABLE TO 2003-05 YZ450F MODELS IN THIS THREAD.

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.

*************

Model:

Edit Revision Date:

Main Jet:

Pilot Jet:

Starter Jet:

Leak Jet (if any):

Fuel screw/Setting:

Needle/Position:

Filter:

Pipe/muffler:

Altitude Range:

Temp Range:

Humidity Range:

Comments:

*************

OEM 2003 YZ450F® Jetting:

Main Jet: 165

Pilot Jet: 42

Starter Jet: 72

Leak Jet (if any): N/A

Fuel screw/Setting: 2.0-2.5 turns out

Needle/Position: NCVQ-4

OEM 2004 YZ450F(S) Jetting:

Main Jet: 165

Pilot Jet: 42

Starter Jet: 72

Leak Jet (if any): N/A

Fuel screw/Setting: 2.0-2.5 turns out

Needle/Position: NCVQ-4

OEM 2005 YZ450F(T) Jetting:

Main Jet: 165

Pilot Jet: 45

Starter Jet: 72

Leak Jet (if any): 40

Fuel screw/Setting: 1.75-2.25 turns out

Needle/Position: NFLR-4

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Model: 05 450F

Edit Revision Date: -

Main Jet: 165

Pilot Jet: 48

Starter Jet: Stock

Leak Jet (if any): Stock

Fuel screw/Setting: 1.5 Turn out

Needle/Position:#3

Filter: Stock/Twin Air

Pipe/muffler: Yoshimura TRC Pro Series Carbon Fiber w/ muffler shortened 3"

Altitude Range: 500' above

Temp Range: 50-80

Humidity Range: 30-80%

Comments:

Bike is ported/polished with rev box.

If i throw on stock exhaust i run a 162-3 main jet, when its colder than 50 i bump up the main to 168.

Has slight hesitation from idle to quarter throttle, but runs great otherwise.

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Model: YZ 450F 2005

Edit Revision Date: 17/1/10

Main Jet: 165 (stock)

Pilot Jet: 45 (stock)

Starter Jet: stock

Leak Jet (if any): stock

Fuel screw/Setting: 2 turns out

Needle/Position:stock

Filter: twin air

Pipe/muffler: Jardine RT-4 full system

Altitude Range: Sea Level

Temp Range: 10 - 40 deg celcius

Humidity Range: 50 - 80%?

Comments:

Bike runs really well, no bog and very very little popping on deceleration. Will start 2nd kick cold (no choke on most day) with 2 turns of the throttle.

Hot it will start first kick with hot start lever pulled unless it is in gear than it may take 4-5 kicks.

I have the merge Stiff AP spring and adjusted the AP squirt to just miss the slide, Has no perceivable bog at all.

Did not need to change jetting even with new exhaust although i have a large pilot on order

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Model: YZ 450F 2003

Main Jet: 170

Pilot Jet: 52

Starter Jet: stock

Leak Jet (if any): stock

Fuel screw/Setting: 1 1/2 turns out

Needle/Position:middle

Filter: stock

Pipe/muffler: Yoshimura Full exhuast

Altitude Range: Sea Level

Temp Range: 70-80 degrees

Bike starts easily, hot or cold, tried jetting with specs already posted here and with a 42 pilot, jetting was very lean and starting was difficult.

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Model: 05 YZ450

Edit Revision Date: 2-6-2012

Main Jet: Stock 165

Pilot Jet: 150

Starter Jet: stock

Leak Jet (if any):stock

Fuel screw/Setting: 2 turns out

Needle/Position: stock

Filter: UNI

Pipe/muffler: Stock

Altitude Range: 2400 feet

Temp Range: 65 degrees

Humidity Range: probably 40%

It idled like crap and was poping like crazy with the 45 pilot i installed the 50 and it is a freekin dream. I love it. I may mess with the other jets soon.

Edited by homernukem

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Model: 03 YZ450F

Edit Revision Date: 6/11/12

Main Jet: 170 (was 175)

Pilot Jet: 45 (was 50)

Starter Jet: 72 (stock?)

Leak Jet (if any):

Fuel screw/Setting: Moose(?) 2 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: Actually ran really good with the richer 175 and 50 jets, but starts significantly better with the 170/45 setup. Did not "pop" with the fatter jets on decel, but does now. Power and response of both setups is similar the only differences I noticed were the popping and easier starting with the leaner jets. Still tuning the bike. More to come...

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