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hey guys i have a 2006 crf 450x and i was wondering what the stock main jet is the model of the bike is crf450x6 i dunno what that makes a difference but i herd that it would i am putting a fmf power core 4 on it also do you have any suggestions on what size jet ill need for it i live and ride in north alabama and south tennessee i want a big enough jet to were when i put a airfilter on it ( which will be soon ) that i dont have to go back in the carb and change jets any suggestions is appreciated

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hey guys i have a 2006 crf 450x and i was wondering what the stock main jet is the model of the bike is crf450x6 i dunno what that makes a difference but i herd that it would i am putting a fmf power core 4 on it also do you have any suggestions on what size jet ill need for it i live and ride in north alabama and south tennessee i want a big enough jet to were when i put a airfilter on it ( which will be soon ) that i dont have to go back in the carb and change jets any suggestions is appreciated

Chris... you'll get lots of good advice here...

But, have you called FMF for a baseline when using that pipe?

Changing the main may not be your only solution. And lastly, read up on the jetting FAQ in the stickies... lots of good info there too!!

And changing from a stock air filter... to another, won't change your jetting. Should be the same. In my recomendation... stay with a stock filter or one that retains the rubber surround sewn into the filter media. They work the best (in my opinion and observations).

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i want a big enough jet to were when i put a airfilter on it ( which will be soon ) that i dont have to go back in the carb and change jets any suggestions is appreciated

my stock main was a 142. get the JD jet kit and be done with it.

+1 on staying with the stock filter

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hey guys i have a 2006 crf 450x and i was wondering what the stock main jet is the model of the bike is crf450x6 i dunno what that makes a difference but i herd that it would i am putting a fmf power core 4 on it also do you have any suggestions on what size jet ill need for it i live and ride in north alabama and south tennessee i want a big enough jet to were when i put a airfilter on it ( which will be soon ) that i dont have to go back in the carb and change jets any suggestions is appreciated

I installed the FMF PowerCore 4 with the Powerbomb header + CRF's Only T-Handle fuel screw + JD Jetting Kit .... The result ... she runs great :)

BTW the stock main on an '05 is 142 / the pilot a 45 / FS 1 1/4 out

Here is how I jetted after installing the same muffler on my '05 450X:

Year:2005

Elevation:0-500ft

Temperature Range:40-80F

Smog (AIS):N/A (Canadian Model)

Airbox Modified Top:Yes

Airbox Modified Sides:Yes

Backfire Screen:Stock config.

Air Filter:Stock

Pilot Jet:45 (Stock)

Main Jet:170

Needle:JD Red

Needle Clip Position:4th

Fuel Screw Type:CRF's Only

Fuel Screw Setting: 1 1/8 out

AP Modified:Large o-ring (JD Kit)

Leak Jet:Stock

AP Cover:Stock

Exhaust Type:FMF Powercore 4 w/ powerbomb header

Exhaust Modified:N/A

Pink Wire Modified:no

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ok i put the pipe on and changed from a 142 to a 155 my fuel screw is on factory settings got a lil bit of smoke it that ok? and still stock air filter and it may just be me but about a foot behind the end of the pipe there's a raspy sound like air turbulence or something kinda sounds like its blowing into leaves but as ya no its pretty much aimed up yall ever herd of that? :)

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Still too lean...

And the noise you hear is your pipe turbo... it spins the air on it's way out the can and sounds like a pfffft as it cuts into the new airspace.

:D ....:)

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ok i put the pipe on and changed from a 142 to a 155 my fuel screw is on factory settings got a lil bit of smoke it that ok? and still stock air filter and it may just be me but about a foot behind the end of the pipe there's a raspy sound like air turbulence or something kinda sounds like its blowing into leaves but as ya no its pretty much aimed up yall ever herd of that? :D

I ran a 155 main with the stock muffler (with baffles cut out) and airbox mods done ... I think you're gonna have to head up in to at least the 165 range on the main jet !

A lot will depend on the conditions you ride in --- temp. and altitude !

Have you done the spark plug test yet ???

This can be a good indicator of how a particular main jet affects the mixture (too rich or too lean) :)

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''got a lil bit of smoke it that ok? ''

BTW ... mine smoked a little bit as well the first time I fired it up !

I was told that this is normal.

I was told that they oil the interior of the pipe at the factory to prevent rusting during storage ... the smoking won't last very long ! :)

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oh ya do any of you have a pic of the fuel screw that you have to adjust just wanna make sure im on the right one when i do it 06 crf450x

thanks

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oh ya do any of you have a pic of the fuel screw that you have to adjust just wanna make sure im on the right one when i do it 06 crf450x

thanks

it's the brass screw in the top left corner. make sure you bottom it in and then start the adjustments. don't go more than 2.5 turns out otherwise you risk it falling out.

float-drain-bolt-2.jpg

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You might want to consider an aftermarket fuels screw (replacement) if you are gonna start making FS adjustments ! they are a 'relatively' inexpensive mod that make this part of tuning a lot easier !

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