YFZ450 Jetting

[Randog]

I could use some of your guyz'z help with Jetting.

I have an 04' YFZ450

Pro Circuit T-4 pipe

K&N intake filter

Removed air box top

Ride 99.9% in sand. ( Dumont ) Yiah Yiah!

Can anyone steer me in the right direction for Jetting?

Main size, Pilot size, Needle position, Turns out on the fuel screw?

I did call Pro Circuit and got some info.

Just wondering DDR's opinions....

Thanks Mangs,

R-

Edited July 25, 2008 by Randog

[TheAlaskan]

I had a horrible time trying to get my yfz jetting right....Finally found the right mixture and had it all logged and saved on my computer. Including all old and new modifications and jet set ups and what worked and didnt work......then my hard drive took a chit and I lost everything

I'll have to think about it for a bit and see if I can remember what I have in there now

[Randog]

I had a horrible time trying to get my yfz jetting right....Finally found the right mixture and had it all logged and saved on my computer. Including all old and new modifications and jet set ups and what worked and didnt work......then my hard drive took a chit and I lost everything

I'll have to think about it for a bit and see if I can remember what I have in there now

Ahhh, that sucks Ian.

Well at least you got it runnin' right.

Why don't you tear your quad down and post what you got in there. J/K

Anything would help. Hopefully I don't have that much trouble.

Thanks though mang.

Your story makes me want to sit here and burn CDs all day.

Anyone else got info?

BUMP

[indasand]

I can't remember, Dan set it up for me on his dyno

[mineurbiz]

Randog, get ahold of Aaron or 1badyfz (sam), they are great at that with the YFZ's. You can also go to YFZTECH.COM some very smart individuals over there.

[TheAlaskan]

Ok, I'm pretty sure I have a 195 main, 50 or 55 pilot 2.5 turns out on the mixture screw and stock needle position (mines an 07, needles not adjustable)

[mineurbiz]

Setting are going to be different for different setups, but I will look at my stock (sitting on the shelf) and see what I was jetted at with a Whitebro's, K&N, no lid, when I get home (late) tonight. I might be able to look at it before I have to go to a Bday party, if so I will post up what it was set at. maybe we will atleast get you in the ball park

[Sand_YFZ]

I would start here.Around 175 main,45 pilot,2 turns out on the fuel screw.Get the NCVQ needle and put it on the middle clip.Good starting point.If you plan on keeping the mods you have i would buy a 170,172,and 175.The 45 pilot should work fine so i wouldnt go to crazy with that.The needle is the YZ450 OEM Stock needle.Most shops will have it.

Here is the needle part number

5TA-14916-V1-00

Good Luck!!

[TheAlaskan]

Ok, I'm pretty sure I have a 195 main, 50 or 55 pilot 2.5 turns out on the mixture screw and stock needle position (mines an 07, needles not adjustable)

I wrote ^ at work so I didnt get a chance to put my mods on.....

-Cam mod on exhaust cam

-Hot cams intake cam

-FCI intake and filter

-no airbox

-Thunder Alley custom exhaust

I like it to run a little rich, especially since I took out the air box. it sounds like chit at first start up, but once its warm it runs like a raped ape I would still like to get it dyno tuned some day though

Whatever you do....DO NOT use a dynojet kit....thats why it took me so long to get it set up initially. your better off just buying a couple of individual jets and an adjustable needle for a couple bucks

[powerhouse]

hey Randy, put a 178-180 main with a 45 pilot and turn the screw out 3 1/2 turns needle in the 5th clip

Edited July 26, 2008 by powerhouse

[Randog]

Right-on you guys. Thanks for all the input so far.

Here's where I'm at so far with this:

I went to Yamaha to get the NCVQ needle. (which I got )

The owner who has been building motors for what seems like forever,

told me that Pro Circuit really does their homework.

He said they know jetting for their pipes.

He said to go with what Pro Circuit said. Which was:

NCVQ needle on 4th groove from top

162 main

40 pilot

1.75 turns out on screw

These jets sound awfully small compared to all your success and suggestions. :black:

I have to admit, I'm a little confused and concerned now that there is such a difference.

The Yamaha guy said the stock jets are 165 main 42 pilot.

Why would this pipe make me need to put smaller jets in than stock?

I'll pull the carb and see what is in there now for evaluation, before I go buy new jets.

I was told it was re-jetted when the pipe was put on before I owned it.

Ran great till last trip it was bogging all over the place.

I figured it got sand in the carb so I bought the K&N kit.

Now figured more re-jetting is required.

You guys need to know that I totally appreciate all your help with it. :foshizz:

R-

[powerhouse]

Right-on you guys. Thanks for all the input so far.

Here's where I'm at so far with this:

I went to Yamaha to get the NCVQ needle. (which I got )

The owner who has been building motors for what seems like forever,

told me that Pro Circuit really does their homework.

He said they know jetting for their pipes.

He said to go with what Pro Circuit said. Which was:

NCVQ needle on 4th groove from top

162 main

40 pilot

1.75 turns out on screw

These jets sound awfully small compared to all your success and suggestions. :black:

I have to admit, I'm a little confused and concerned now that there is such a difference.

The Yamaha guy said the stock jets are 165 main 42 pilot.

Why would this pipe make me need to put smaller jets in than stock?

I'll pull the carb and see what is in there now for evaluation, before I go buy new jets.

I was told it was re-jetted when the pipe was put on before I owned it.

Ran great till last trip it was bogging all over the place.

I figured it got sand in the carb so I bought the K&N kit.

Now figured more re-jetting is required.

You guys need to know that I totally appreciate all your help with it. :foshizz:

R-

stock is 158 and 42 [ jetting changes with needle changes ] good luck Randizzle

Edited July 27, 2008 by powerhouse

[Sand_YFZ]

Does Pro Circuit recommend that jetting for all 50 states and all elevations? Ive had my YFZ at all different stages of builds from pipe and filter,built stockbore,480,stroker etc.When I had ESR pipe,ESR Intake,and cam mod running u4 my jetting was between 178 and 180 for Dumont with a 45 pilot and 2 turns out with the NCVQ on the center clip.Thats why I figured a 175 with pump gas with the same pilot and air screw turns.Another thing that helps alot is changing the leak jet on the bowl.I think it needs to be a #38 0r #40.In the 04 the leak jet isnt a very good size and can cause off idle bogging.Another solution for this is the quickshot accelerator pump cover.I did both.Just my experiences,good luck..Ive always gone with real world results and not dealer recommendations.

Edited July 27, 2008 by Sand_YFZ

[rushjunkie]

For whatever its worth, i used powerhouses' suggestions on my '04 and it ran beautifully last time out. i have similar mods:

Dr. D exhaust

GYTR filter (no lid)

GYTR jets and needle

I guess i have another question, that jetting worked great in february when it was nice and cold, but i am trying to head out for the night ride, will it run fine with the same jetting? i know different temp air will have different density, but is it enough to screw with my jetting? im not trying to go out and drag everybody, i just want the engine to be safe for some duning...

[powerhouse]

For whatever its worth, i used powerhouses' suggestions on my '04 and it ran beautifully last time out. i have similar mods:

Dr. D exhaust

GYTR filter (no lid)

GYTR jets and needle

I guess i have another question, that jetting worked great in february when it was nice and cold, but i am trying to head out for the night ride, will it run fine with the same jetting? i know different temp air will have different density, but is it enough to screw with my jetting? im not trying to go out and drag everybody, i just want the engine to be safe for some duning...

yeah , I would keep it the same .

[Randog]

Ok guys, here's what's goin' on:

I'm just going to re list everything.

My 04' yfz450 ran good in past.

Started cutting out all across the board.

Figured it got sand through the intake.

Decided I'd put a K&N on it.

Need to re-jet for K&N.

Here's what it's been set-up with:

Pro Circuit T4 complete pipe.

Stock air filter.

162 main

48 pilot

NCVQ needle on 4th groove (middle)

30 leak jet?

3 turns out on screw

I'm putting the K&N on now.

Run in Dumont (2000 feet ASL) 99% of time.

So now with the facts of what's been in there:

What jet recommendations do you guys have for me?

I'm thinkin' just go up with the main to ???.

Also the NGK CR8E plug had black carbon and gap was @ .033" (rec. .028-.031).

Thanks,

R-

[Randog]

Bump for a lost dog. :mischevious:

Just want to run this by you guys really quick before I go buy jets.

I'm thinkin' just goin' up on the main a couple ( 165, 168 ) ?

Thanks Yo's.

R-

[mineurbiz]

Randog,

Question for you, in your post you said that you think sand got through the intake possibly? I would check to see if the carb is clean before you run it anymore. If you got sand in it, you have sand in your motor or will.

[Randog]

Randog,

Question for you, in your post you said that you think sand got through the intake possibly? I would check to see if the carb is clean before you run it anymore. If you got sand in it, you have sand in your motor or will.

Thanks Mark.

I saw a couple grains in the rubber boot between the stock filter and the carb.

I think we'll be fine to say the stock filter was doing a decent job.

I still put the K&N kit on there. I trust them more.

I have the carb off and on the bench.

I'm planning to spray the chit out of it with carb spray before re-assembling it.

There was a small lacquer looking substance in the area where the slide would hit if it could fully close off the intake hole.

Don't know if that's normal.

Also, is it bad to transport a YFZ with it standing on the rear Grab bar?

Could this be causing me problems?

R-

[Sand_YFZ]

main needs to be atleast a 175 pilot a 45 and if its still cutting out you might need to take a look at the stator.I had my stator go out on my 04.These arent THAT sensitive to jetting.Anything less than 172 on a piped YFZ is too lean.When my stator was bad it would cut out really bad at mid/high RPM.I tried jetting and everything under the sun for weeks until i changed the stator and its been great ever since.Another thing is the flywheel.If you put a trailtech flywheel on it then you are almost guaranteed to have problems.Those are garbage.

Edited August 18, 2008 by Sand_YFZ

[TheAlaskan]

Hey Randog, I know you're asking about jetting specs and I'm pretty sure you already have your K&N kit. but if you want a BAD intake check out FCI Intakes I had the Pro design K&N kit on my and switched to the FCI....huge difference, I love it!

[Randog]

main needs to be atleast a 175 pilot a 45 and if its still cutting out you might need to take a look at the stator.I had my stator go out on my 04.These arent THAT sensitive to jetting.Anything less than 172 on a piped YFZ is too lean.When my stator was bad it would cut out really bad at mid/high RPM.I tried jetting and everything under the sun for weeks until i changed the stator and its been great ever since.Another thing is the flywheel.If you put a trailtech flywheel on it then you are almost guaranteed to have problems.Those are garbage.

Cool Aaron,

I'll start there 175 and 45.

This is goin down on the pilot, but sounds like that's in the range everyone is running.

Hope it's not the stator, but we'll see. I got dirt tire for testing on the street.

Thanks man.

Hey Randog, I know you're asking about jetting specs and I'm pretty sure you already have your K&N kit. but if you want a BAD intake check out FCI Intakes I had the Pro design K&N kit on my and switched to the FCI....huge difference, I love it!

Ian, that intake looks sweet.

I see how it would be better by getting rid of the squashed stock rubber duct from the filter to the carb.

Theirs looks like it would flow way better.

I am going to have to stick with the K&N (budget) for now though.

I'm not a racer with the quad, just want it to run good.

Plus my GF putts around on it when she's not reading a book.

Thanks for the info guys.

:hungry:

[TheAlaskan]

Cool Aaron,

I'll start there 175 and 45.

This is goin down on the pilot, but sounds like that's in the range everyone is running.

Hope it's not the stator, but we'll see. I got dirt tire for testing on the street.

Thanks man.

Ian, that intake looks sweet.

I see how it would be better by getting rid of the squashed stock rubber duct from the filter to the carb.

Theirs looks like it would flow way better.

I am going to have to stick with the K&N (budget) for now though.

I'm not a racer with the quad, just want it to run good.

Plus my GF putts around on it when she's not reading a book.

Thanks for the info guys.

:hungry:

Right on, Good luck with the jetting. Just dont test it out on the street (the police don't approve )

and yeah the two intakes side by side are a night and day difference

[Randog]

WooHoo.

Last night I got the quad back together, Fired right up first thing this morning.

Came home tonight for a test ride, Rattled the neighbors up and down the street a couple times.

Idles awesome

Pulls really hard out of the hole

Starts cuttin' out on top end

Pops on deceleration

Oh and runs way better with the gas on

It's got 175 main, and 45 pilot

I've got a 178 main I can throw in. Is that a decent jump?

What to do for the popping?

Thanks,

R-

[TheAlaskan]

WooHoo.

Last night I got the quad back together, Fired right up first thing this morning.

Came home tonight for a test ride, Rattled the neighbors up and down the street a couple times.

Idles awesome

Pulls really hard out of the hole

Starts cuttin' out on top end

Pops on deceleration

Oh and runs way better with the gas on

It's got 175 main, and 45 pilot

I've got a 178 main I can throw in. Is that a decent jump?

What to do for the popping?

Thanks,

R-

ok when jetting always remember this:

idle to1/4 throttle = pilot jet

1/4 to 3/4 = needle

3/4 to full throttle = main jet

so cutting out on top end (if full throttle) go up on the main

and popping on decel up the pilot jet 1 or 2

what's your idle screw set at?