question on jetting

[Jostud]

I have a 2007 yfz 450se with Dr D slip on exhaust, i recently purchased the boysen quickshot accelerator pump cover, and a ride engineering air/fuel mixture screw. I am haveing trouble eliminating the hesitation bog with the first crack of the throttle. Which was what the quickshot & air fuel screw is supposed to do.. I followed instructions and have the air fuel screw turned out 2 1/2 turns, and have been trying to adjust it in and out. I am currently running a 162 main jet, and i live in NW corner of Iowa all other jets are stock. Air filter is clean, fuel is fresh 91 octane, what should i try changing to elminate the hesitation?? any help would be appreciated.. Thanks!!













2007 YFZ 450SE:
* SRP steering stabilizer
* +2 steering stem "custom"
* 3" Billet spacers up front 1.5" per side
* 4" Billet spacers out back 2" per side
* Quick shot accelerator pump cover
* Ride Engineering air/fuel mixture screw
* Twin Air air filter
* In Line coolant super cooler
* AC Racing Pro Nerfs Black w/ pegs
* Pro Armor Pro MX Front Bumper
* Pro Armor Pro Series Tether Kill switch
* Holeshot XC rear tires
* ITP .190 T-9 Pro Lock Black Beadlocks on rear
* Engine Ice coolant
* Motion Pro Twist Throttle
* Mod Quad E-Brake block off plate
* Vented Gas Cap
* Heat Temperature Strips

[ohsobad_chevy]

You need to completely jet the quad...pilot, needle, main, screw.

Do a search on jetting yfz, you will find some good information to read.

With your mods, I would start with:
170 main
45 pilot
The NCVQ needle on the 4th pos. from top. (stock 2007 needle is not adjustable)
#35 leak jet

[#17YFZRACER]

you might want to even try a 48 pilot. thats what i run

if you need an ncvq needle i am selling them on ebay. thanks

[Jostud]

I took my needle out last summer and we adjusted it 1 notch, but I forget which way up or down. What exactly is a NCVQ needle from another bike/quad, or just an aftermarket needle? I will tear it apart tomorrow and see where the clip is at. And also, do you recommend I buy a jet kit, or go to a local shop and purchase individual pilot jet, leak jet, main jet and NCVQ needle?.. I have a 162 main jet in it now, i tried the 165 and it shot flames out the exhaust 6 to 8 inches So i dropped back down to the 162. Also what is stock main, pilot, leak jets on the 07 yfz?? Thanks for the help guys!! I really appreciate it!

pm sent

[leveldrummer]

the leak jet is going to be a big part of it, the accelerator pump doesnt throw enough full into the bike when you jab the throttle, its because the leak jet they have in there is huge! put in the 35, and the rest of the jets reccomended, it might take a little fine tunning, but even if it doesnt run perfect after you jet it, its still going to run like a raped ape compared to stock, so hold on!

[ohsobad_chevy]

Originally posted by leveldrummer
the leak jet is going to be a big part of it, the accelerator pump doesnt throw enough full into the bike when you jab the throttle, its because the leak jet they have in there is huge! put in the 35......

Leak jet sizes are opposite of regular jets, the bigger the number, the smaller the orifice. ;)