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Jetting FAQ's

382K views 1K replies 560 participants last post by  jordanmolinaro98 
Well thanks Edgerat!! :D

I finally made it to the shop to get a couple of jets, and got the baffle out, lid off, and cam mod,put the 168 main in, 45 pilot, moved the clip on the stock needle down to the 5th position. And all I can say is WOW :O its almost like I bought a whole new bike for the $8 bucks the jets cost me. :lol


Anyone that has not done this yet I say DO IT!!

The POWER is great!!! :yfz
 
By the way I am at 2000ft and it is 85-90 degrees here.

It might be a little rich but oh well it feels like lots of power everywhere, no stumbles or boggin at all!!!!
 
Sent the instructions.

But folks realize these just tell you how mecanically to jet, not how to actually dial the bike in with jet sizes.

Scott
 
OK fellas I will send you the JD instructions but to everyone else let me make this clear these just tell you mechanically how to jet, not how to dial your bike in. OK

Scott
 
Moving the needle down to the 6th clip will help a little but you are still gonna be lean at 3/4-WOT cause the fuel cant flow past the small stock main jet.
 
The head pipe is gonna glow some. You are not too lean with a 180 main there is no way.
 
Originally posted by McDowell@Mar 1 2004, 07:19 AM
ok, here it goes:

with an HMF slip-on and air box lid on, i'm now at a 170 main, YZ NCVQ needle 3rd clip, 48 pilot, Zip-Ty screw at 2.5 out. seems ok except if i crack the throttle open hard from idle it dies at about 1/4 throttle. does fine if i open it slower but just quits if i open it quick. i tried the needle at 4 w/ same result. i also adjusted the screw everywhere from 1 to 3 turns w/ same basic result. my brother's YFZ is identical except 175 main and stock needle stock clip and dies at the same point.

my thought is that the pilot is a tad too big and i should try a 45.

ANY helpful suggestion would be appreciated. thanks.
Do the cam mod and then that 48 pilot will be spot on.
 
Well I am not gonna explain the cam mod again.
But you don/t lose any bottom, but you do gain alittle top, what is the problem there.



Anyway it will take all of 2 minutes to try the 45 out.

Put it in and see how she runs.

I bet you need to do some more tuning on the screw though and turn the idle up alittle more.

Try setting the screw at 1.5 turns out.

Why did you put it at 2.5 anyway? Because everyone said to?
 
Originally posted by superdave@Mar 10 2004, 06:16 AM
Yeh, I work part time at a Yamaha shop so I I bought the jet kit form the shop. My understanding is that the YZ450 needle is the same thing. SO all you need is a couple of main jets and one or two pilots. ...I started working at the shop after I bought the 450 so I did not get a great deal on it, but parts are cheaper......
You are not saying that the YZ needle is the same as the YFZ are you?
 
I sent them to you.


Remember fellas these instructions do not tell you how to dial your bike in they tell you what parts to take off to install the jets.
 
I would start with the 168 main, 3rd clip on the needle and the 45 pilot.

Go from there.

With temps up you can jet leaner. If it pops some in the mid range or when letting off put the clip on the 4th spot.

BTW your welcome :D
 
BS, with the temps up around 90 that bike will be so damn fat it will barely run.

FAST1 I run a ESR K&N kit, ESR pipe cam mod at Dumont 500ft 90 degrees, and only run a 172 main 48 pilot and the NCVQ needle on the 5th clip.

My bike has great throttle response and is hella fast on the top end.

You boys need to lean your bikes out some with the higher temps and you will see how these things are really supposed to run.

You can't jet for the winter and expect it to run great in the summer too. :wtf
 
Originally posted by FAST1@Mar 26 2004, 07:07 PM

Interestingly, when we discussed jetting specs last summer (mid- August), you suggested I run a 168 main, 3rd clip on NCVQ needle, 45 pilot and that was with a full GYT-R exhaust and a FOAM GYT-R filter with lid off. Now you suggest the same jetting for a K&N which obviously flows more air than the foam filter.

I would allways start rich and know your rich, then lean down the main and needle clip. Your even running a 172 main, correct?
I did and I realized that I and alot of other folks were actually jetted richer than need be.

And yes I do run a 172 48 pilot, 5th clip on NCVQ needle and 1.5 turns out on the mixture screw.

With
ESR pipe
ESR intake (no airbox, more air than just a K&N in the box)
YZ EX cam
and head cleaned up (reason for bigger main, was 170 and 4th clip before)

There you have it.
 
Originally posted by PhatFireMan@Jul 5 2004, 01:18 PM
Are you telling me to go lower from experience...or by the symptoms I described? Thanks!
Experience.....I have none.

Read the disclaimer below.
 
Yup your jetting specs sound right on to me, I told you to go down in main size a while back.

You are jetted close to me, I am at $2200ft and have the head ported so I am just alittle bit richer.

As for Glamis its at sea level so yes you will have to jet alittle richer than you are now.
 
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