Jetting 101.

[crawlerman]

my 08se does not have but 1 place on the needle where the clip can go. WTH

[jannypan]

Is the TPS the thing the pen is on? (I think thats the idle) Or is the where the arrow is? Im confused!

[The Calamity]

Ive searched high and low for someone with same setup as me and close elevation and i cant seem to find info..

I got a new 08 yfz450 se about 4 months ago..
I put these mods on within a month ago

Mods are:
Sparks racing x-6 Full pipe (with SA screen installed)
Sparks filter with lid removed
Sparks Jet kit.
175 Main
45 Pilot
4th clip on needle from top
2 turns out

The throttle response is great.. from idle to WOT it screams.. with no backfires on deceleration.. my problem lies from 1/4 to 1/2 throttle. if i hold it between there is feels like it misses/sputters. I thought maybe i was rich in the main.. i tried a 170 and made it worse and also had backfires on the decel. Went back to 175. Not sure if i should try fuel/air screw or which way to go on the needle..

Anyone point me in the right direction?

Oh.. elevation is 2000 feet 60-90f normally

TY for your time,
Chris

[Sparty]

Could someone send me the photos also? Also where are you guys buying the jetting kits (jdjetting.com?)

[cootertrucks]

The Example pictures are missing. help please???

[cruzsofializ]

hello,i love yamaha.

[07_YFZ450]

I live at 800ft above sea level....I bought an 07yfz from a guy about a week ago and cannot get the jetting right at all.....I just want to go back to stock does anyone know the stock sizes? I know looking at the bottom of the carb in a line the top is pilot, center is main, and bottom is ? if the leak is in the bowl? Anyone?

[ninjayfz]

im having problems getting my jetting right. idle seems to be OK. i think it might be on he rich side. im not having any problems on the wot. but in mid range its not running right..i think it would be called 'hesitating'. it acts like its lean to me but when i move the clip to richen it gets worse. same as if i leaned it..

i dont know what else to do besides having a shop shop do it and spending $$$$.

1000 ft
big bore 480
ncvq 5th
boyesen quick shot
main 185
pilot 58
mixture 4 turns
sparks exhaust
k&n
air lid on

[jannypana]

The TPS is what the arrow is pointing to. The pen is pointing towards the idle screw.

[yfz&f4i]

This sticky is worthless without the photos. Come on guys, any chance you can get those photos back up here and make this thread official again.

[Brillo]

I have an 08 with a lrd pro4r and a k&n with the lid off. I run at 1600 ft in antigo wi and it has a 165 main, 45 pilot and it runs great except for after you keep it full throttle for a few seconds in 5th gear and it seems like the choke doesnt really do anything at idle. Am I runny too small of a main jet?

[YFZ450~BENCE]

ya i dont know why people delete photos from their photobucket or delete the account. Ive had mine for years and just leave it alone, its just there just so it can be just there when i need it. haha

[anjiegal27]

hello,im newbie of this cool forum and im so glad to be in this thread.

[RichM1983]

I don't want to create a new thread for this so hopefully someone in here can help. The main jet is a 175, the leak jet is a 90, and the pilot doesn't have a number? I have no way of knowing what it is. Air screw is 2 turns out and the clip is a on the 3rd one down from the top. My mods are no sparky in exhaust and no lid. Otherwise stock.

My question: Should the jetting be ok?
What size pilot do I have since it has no number?

[rodney-meeks]

Where can i go to see the pics to this awesome write up

[yernkie]

Pics would be great. Can anyone forward them to my email (jschlegel@live.com)?

[alabaster]

Originally Posted by ninjayfz

im having problems getting my jetting right. idle seems to be OK. i think it might be on he rich side. im not having any problems on the wot. but in mid range its not running right..i think it would be called 'hesitating'. it acts like its lean to me but when i move the clip to richen it gets worse. same as if i leaned it..

i dont know what else to do besides having a shop shop do it and spending $$$$.

1000 ft
big bore 480
ncvq 5th
boyesen quick shot
main 185
pilot 58
mixture 4 turns
sparks exhaust
k&n
air lid on

ninja did you ever take yours to the shop?

i have the same issue. i just added:

hmf performance exhaust system
gytr jets:
170 main
48 pilot
3 turns on the pilot
ncvq 4th (was on 6th)
stock air filter w/ lid off (i've rode down the street with no filter on as well)

I am about 2000 ft above sea level in Las Vegas. At one point i was shooting lots of flames out the pipe after just the exhaust and jetting. then i added the needle and from 0-25% throttle it rips, 25-50% is $h!t and 50-100% rips. I've messed with the needle and it doesnt seem to help.