06 YZ450 Leak Jet Change?


9 replies to this topic
  • Blaster21996

Posted February 04, 2006 - 05:52 PM

#1

what the heck is Yamaha thinking? Getting at the carb, is like trying to brush your teeth without bending your elbow. Anyway.... I am changing the MJ to a 170 and changing the pilot to a 48, but, since I have it all apart I figured I'd change the LEAK JET wile I have the access. Anyone experimented with LEAK JETS yet? The factory is a 55, a far cry from the 90 that came in my 05 YZ250F. I think I will try a 45.

Anyone have a clue

  • Jeff_Ashe

Posted February 04, 2006 - 06:13 PM

#2

I did extensive jetting with the 04 and 05 250F. Been working on the 06 250F and just got my 06 450F yesterday. This much I can say for sure. The jets on the 06 450F are much closer than anything on the 250s. I would recommend leaving the AP alone for a bit and concentrate on your MJ and PJ. The stock setting on the PF is a surprisingly 2-1/8 turns. Considering that the jet typically maxes out at about 3 turns, that does not leave much room for cold air at sea level (like here). I am thinking a 45 PJ and leave the AP alone for now. It was warm (65) here today and the bottom end was nothing short of awesome. But that was with the PJ at 2-3/8.

  • Blaster21996

Posted February 04, 2006 - 06:23 PM

#3

I did extensive jetting with the 04 and 05 250F. Been working on the 06 250F and just got my 06 450F yesterday. This much I can say for sure. The jets on the 06 450F are much closer than anything on the 250s. I would recommend leaving the AP alone for a bit and concentrate on your MJ and PJ. The stock setting on the PF is a surprisingly 2-1/8 turns. Considering that the jet typically maxes out at about 3 turns, that does not leave much room for cold air at sea level (like here). I am thinking a 45 PJ and leave the AP alone for now. It was warm (65) here today and the bottom end was nothing short of awesome. But that was with the PJ at 2-3/8.


Thank you for replying! :thumbsup: I hear what you are saying about the AP, coming stock with a 55 leak jet indicates that someone at Yamaha must have looked at the jetting posts on Thumpertalk! :thumbsup: I will leave it alone for now!

As far as the pilot jets, have you tried the 45 yet? I see several posts recommending the 170MJ and 46PJ combination?

  • Jeff_Ashe

Posted February 04, 2006 - 06:33 PM

#4

I have not tried jet changes yet. It was unusually warm here today (65F), so stock setup ran fine. Plus, I stayed up most all night putting on the new chain, new front tire, graphics and doing break-in runs and oil change. Was just too tired to brush my teeth without bending my elbow to get at the jets!
I'm pretty sure that the 42 PJ will not make it at this altitude (<1,000'). So I will try a 45 this week. For now I can't resist riding it!

  • Matt96xr6

Posted February 04, 2006 - 08:46 PM

#5

Seems on the 450s the 48/170 is the ticket to jetting them.

Previous 03-05 450s use the #40 LJ in them.

A trick on the new 06 frames is to remove the seat, tank and shrouds (as one unit) and then remove the upper motor mounts. Loosen both ends of the air boots on the carb and then you can turn it like a 2 stroke to get at the bowl. Really simple!

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  • Blaster21996

Posted February 04, 2006 - 11:01 PM

#6

Seems on the 450s the 48/170 is the ticket to jetting them.

Previous 03-05 450s use the #40 LJ in them.

A trick on the new 06 frames is to remove the seat, tank and shrouds (as one unit) and then remove the upper motor mounts. Loosen both ends of the air boots on the carb and then you can turn it like a 2 stroke to get at the bowl. Really simple!


I'll try that next time.

I took the seat & and tank off as one peice, then seperated the air box from the subframe and removed both. After jetting, I installed the air box, then the sub frame followed by the exhaust. That went very well! :thumbsup:

  • mcfadyen1968

Posted February 05, 2006 - 05:51 AM

#7

Hey! If you are going to take the time to pull the carb put the 170 main in and change the pilot and put in a adjustment screw. pull the screen and put a backfire filter in and this thing will fly. I also put on a cr high bend handle bars and 98 mm sag raised the forks and looped out the first two turns.

  • jeffboyd47m

Posted February 05, 2006 - 11:53 AM

#8

Seems on the 450s the 48/170 is the ticket to jetting them.

Previous 03-05 450s use the #40 LJ in them.

A trick on the new 06 frames is to remove the seat, tank and shrouds (as one unit) and then remove the upper motor mounts. Loosen both ends of the air boots on the carb and then you can turn it like a 2 stroke to get at the bowl. Really simple!

Instead of removeing the motor mounts just remove the hot start. Its simple and works like a charm. Plus you can put a dab of grease on the hot start while you have it off.

  • dangwartz

Posted February 09, 2006 - 08:56 PM

#9

Hey! If you are going to take the time to pull the carb put the 170 main in and change the pilot and put in a adjustment screw. pull the screen and put a backfire filter in and this thing will fly. I also put on a cr high bend handle bars and 98 mm sag raised the forks and looped out the first two turns.



I'm new to thumpers. What is "the screen" and a "backfire filter" and what do they do?

Thanks in advance.

  • Blaster21996

Posted February 09, 2006 - 10:08 PM

#10

I'm new to thumpers. What is "the screen" and a "backfire filter" and what do they do?

Thanks in advance.



All thumpers have a metal mesh (screen) air filter cage to help retard any sparks from melting or other wise incinerating your ass :thumbsup: . It is believed that this screen hinders airflow, thus, you can buy an aftermarket filter cage sans the screen from places like Twin Air. http://www.twinairus.../powerflow.html





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