YFZ450 Jetting .

[BennyYFZ]

hey guys, thank you for the information!

I will see what I can come up with here w/ jetting changes.

Bill, my mods are:

2004 Yamaha YFZ450
Ron Woods full exhaust
Cam mod
CP Race Piston 94mm
Velocity Intake w/ airbox removed

I'm in DFW, Texas which is roughly 600ft above sea level. Temps are roughly in the 50's these days.

[WoodsRacer16]

Hey i have just got in to racing xc this summer in middle tn and i never jetted a quad in my life.I have a stock 07 yfz 450 and i just got my new hmf pipe.Could yall just tell me what i need to do and how to do it lol... im a little lost on it...thanks

[ohsobad_chevy]

Originally posted by WoodsRacer16
Hey i have just got in to racing xc this summer in middle tn and i never jetted a quad in my life.I have a stock 07 yfz 450 and i just got my new hmf pipe.Could yall just tell me what i need to do and how to do it lol... im a little lost on it...thanks

Start with a 170 main, 45 pilot, 3rd needle position, and 2.5 out on the screw. That will get you close.

[Bill Fuller]

45 pilot is to lean. I wouldn't put anything less than a 48. NSDR needle 3rd clip 170-175 main with open airbox.

[ohsobad_chevy]

Originally posted by Bill Fuller
45 pilot is to lean. I wouldn't put anything less than a 48. NSDR needle 3rd clip 170-175 main with open airbox.

Jetting isn't the same for everyone, temperature, elevation, different pipes, carbs, intakes, etc etc.
There is no way to tell him EXACTLY what he would need. That will get him close.

I have a sparks pipe and FCI intake on my 07 and a 48 pilot is way too rich, even in the colder months.

[Bill Fuller]

Except for the fact that he lives an hour away from me with close to the same set up. And I agree that it's only a starting point and I UNDERSTAND elvation, humudity, temperature, setup ETC......

[mxpimp2000]

can anyone help me out on jetting

HMF slipon
cam mod
uni filter no lid
13:1 piston
168 main
48 pilot
2 1/2 turns out
stock needle non adj
temps are around 80-90 when i ride and im 500-550 ft above sea level in the lower Ky area

bike is hesitating when u punch it from 1/2 throttle and if u hold it at half in nuetral it will cut in and out and backfire when u punch it from 1/4 it dies people are telling me its my jetting i just had motor rebuilt and changed exhaust from a TC full system to a hmf slipon with stock header, i didnt mess with the jetting any

[ohsobad_chevy]

Adam,
We have answered you many times in your thread. We told you what jets/needle to order......have you done so??

[yfz4506]

What jetting should i use, i have
GYTR slip on
K&N filter with pre-charger baggy NO LID
05 bottom end with 06 head

[ohsobad_chevy]

Originally posted by yfz4506
What jetting should i use, i have
GYTR slip on
K&N filter with pre-charger baggy NO LID
05 bottom end with 06 head

Start with 170 main, 45 pilot, 3rd clip on needle and 2 turns out on the screw.