YFZ450 Jetting .

[cdalexct]

Originally posted by Quad18star
Stock pipe ?? airbox lid on or off? Temps ?? Elevation ??

HMF full system
airbox lid off with prodesign proflow kit(foam)
airbox lid outwear
35 degrees out runs good
Live in PA dont know Elevation

[Quad18star]

Originally posted by cdalexct
HMF full system
airbox lid off with prodesign proflow kit(foam)
airbox lid outwear
35 degrees out runs good
Live in PA dont know Elevation

Perfect ... thanks for posting more info .... I think the average Elevation in PA is the same as I have ... anywhere from 700ft to 1300 ft .

[Bill Fuller]

HMF full system with Quiet core insert
UM aluminium air box w/250R Uni foam filter,lid on
North Tenn 500ft elvation
Fuel screw at 2 turns out
165main
45 pilot
NCVQ needle on 3rd clip
94 Ultimate

[Fred55]

Thats exactly what im running except a 42 pilot, what temp are you at?

[Bill Fuller]

Wintertemps range from 20 to 50 degrees.I was running a 162 until I put on the UM airbox/250R Uni.

[Fred55]

Your like the only other person that ive seen with a 165 besides me...everybody says to try 168, and i tried that and i was WAY too rich...weird huh

[Bill Fuller]

I followed HMF instructions and my quad ran like CRAP.I started with the 175 main and the 45 pilot.I went to the NCVQ needle right from the start.It took about 2 months to get it to where I am now,believe me I tried all the combos.I finally ordered jets from 160 to 180(Carb parts wharehouse)When I had the 170 in it ran like there was water in the gas.When I kept messing around,thought I was there with the 165 main.After going to H/M last year I realized that weasn't right either.I started to think there was a deeper problem(rectifier/electric).But I finally got the 162 in and BINGO there it was.

[Fred55]

yeah it seems that you and i are leaner that everybody else, which is weird too...with full exhausts and filters, i wonder what is causing them to go up so high as 172 and even 180 as hmf suggests

[SRH]

what do you guys recommend for this setup as a good starting point

lid on
dr d slip on w/ fmf powerbomb "sx" header
cam mod
uni air filter
1200 ft above sea level
60-80 degrees
pump gas 93

from what i read about what alot of guys run i was thinking a good starting point would be

168 or 170 main ( what do you guys think)
45 pilot
nvcq needle 4th clip
air screw 2.5 turns out

anyone have a better idea for a good starting point? my quad felt sluggish at times last year and had a slight bottom end hesitation at times with the dyno junk kit and i really wanna solve that

[Fred55]

I have a 165 main
42 pilot(stock)
3rd clip on NVCQ clip
3 turns out on fuel screw

Im at about 1000-1100 ft
and at the moment temps are around 40, i raced a 1 hour harescramble yesterday and it ran great.