YFZ450 Jetting .

[mxpimp2000]

rockymountain or jets r us

[follick]

i just got a M-7 V.A.L.E. from two brothers. i called their customer service to see what to run for jetting. they guy told me

2005 yfz 450

175 main.
stock pilot.
and clip all the way down on the needle.

i am running a UNI filter.

it hesitates. anyone have an suggestions?

thanks.

[quadrider2112]

07 yfz450 stock pipe tip removed no lid middle Arkansas so elevation varies i ride every weekend so temp varies 30-90
cuts out at 1/2 to3/4 throttle

165 mj
vitos custom needle 3rd clip pos from top
vitos fuel screw 2 turns out
too rich?

[pharmboy]

I just bought a 2008 totally stock. I replaced the air filter with a K&N and went to a 162 main and a 48 pilot. That improved the cutting out when you punch it off idle but it's still seems lean. I haven't torn the car apart yet to see what clip the needle is on but I assume stock. I bought a 165 man and a 48 pilot today and was wondering what you guys thought my next move should be. Which to install first? It idles a little rough especially if I go from accelerating, pull in the clutch, and let it go down to idle. It might even stall. Then punching it from idle to 1/2, 3/4, or full it will usually cut out. Still sounds lean right? Thanks in advance for any help!

[quadrider2112]

i think your next step should be to pull plug and see what it looks like. That will give you an idea. Do you have your lid on or off? 48 may be a hair much to you may need 45. I just bought 45 for mine gonna try that.

lid off
fmf powercore4 slip on
cam mod
175mj
needle 2rd pos from top
vitos custom needle
vitos fuel screw 1 1/2 turns out
45 pilot


runs great need to pull plug to make sure but runs great.

[pharmboy]

I have my airbox on. I installed the 48 pilot and it works perfect.....but it is only 25 degrees here in Michigan. I assume I will need the 45 come summer. Is there an easy way to get to the plug?? Also is there an easy way to get to the carb needle without pulling the carb completely off? Thanks!

[quadrider2112]

I pull the tank cover and then take tank loose and just turn it sideways on the frame and leave gas line attached to check plug. I think that is as easy as it gets and this way you can blow the hole out b4 you pull the plug. The easiest way I know to mess with needle is to pull side skirts and take cable loose from throttle housing on bars. Then take loose air box and intake boot loose from carb. Then carb from intake on motor pull slack in cable. stand on shifter side turn top of carb to point at you and it should slide right out. 2 screws and a plug and your there. It might come out without removing side skirts but it is easier to just remove. [if you have stock needle only way to rich it is to shim it with a tiny washer] which will work my friend did it

[99warriorNJ]

LOCATED IN SOUTH JERSEY. ABOUT 250FT ABOVE SEA LEVEL

TRINITY SLIP ON
FCI INTAKE
GYTR JET KIT

180 MAIN
45 PILOT
#5 ON NEEDLE
2 1/2 - 2 3/4 TURNS OUT

STILL USING THE STOCK AIR BOX WITH SOME SLIGHT MODIFICATION TO THE BATTERY SIDE

[MNyzf]

is anyone running bigger starter jets? i am running a 165 main and a 45 pilot and when i burp the throttle it bogs then pops i have tried everything and it has to be that.....

[Pack]

Okay, so I want a general idea on what jets I need to run...

I have an '07 YFZ450, GYTR slip-on exhaust, GYTR K&N-style air filter with Uni filter vents in the lid, and I live in southern Missouri...

I bought these jets to start out:

170 Main
45 Pilot
Aftermarket fuel screw (not sure how many turns out I should have)
YZ needle (I'm assuming the middle position)
35 Leak Jet

... Should I buy more main jets around that area, or am I way off for where I'm located?

Also, I've heard both ways with a full system exhaust on a YFZ. Is it really necessary, or will I get just as much out of my slip-on since my header pipe's diameter is as large as it is?

Oh, and one more thing: Can I use any air filter cleaner and solvent on my air filter? Like, just buy something at O'Reilly's?

Thanks a ton, guys...