what should i jet my 07 yz250f to

[yz250rac3r]

i bought my 07 yz 250f brand new and it came with two extra main jets i called the dealer and they said this was because they arent built with the best jetting because of emission laws, so ive got a 175 main jet and a 180 main jet what would you recomend i jet it to? the engine is completly stock

 

[IndyMX]

Do a search for jetting. No one can tell you with certainty which jet would be right for you, that's something you have to find out on your own.

There is no magic numbers involved, you have to test and observe and then adjust.

Do a search on here for Jetting, and you should come up with quite a few links that you can read and learn from.

 

[BigRedAF]

This link will take you to Pro Circuit. It's their recommendation for 2007 models. Key word "recommendation" it doesn't mean that you need to rejet your bike. Your elevation may be different, your temps may be different, your bike may be running just fine.

http://www.procircuit.com/PCJETTING.htm

 

[oldguy]

Having owned 4 YZ250Fs and a YZ450F I have only once needed to change the jets. I did on the 450 when we put a new exhaust on it otherwise they have all been pretty darn good as is. I have a 2007 YZ250F in the garage now that is still never ran so if you come up with something let us know but for now I plan to leave it as is until we have raced it a time or 2

 

[crazycarl7]

Jetting

get yourself an adjustable "fuel screw". it will come in handy!!you may not have to change any jets. adjust the fuel screw accordingly and maybe move the jet needle up or down a spot. It maybe that simple.

 

[BigRedAF]

get yourself an adjustable "fuel screw". it will come in handy!!you may not have to change any jets. adjust the fuel screw accordingly and maybe move the jet needle up or down a spot. It maybe that simple.

It comes with an adjustable fuel screw :coocoo:

 

[BigRedAF]

All jokes aside, looking at your post address I see that you live in CT. Other than the cold weather that your enjoying right now your bike should be set up fine as is. A minor fuel screw adjustment may be nessasary due to you cold weather. Perhaps a 1/2 turn out but you will have a hard time getting to it in it's current form.

Several companies make an extended fuel screw that you can reach with your fingers. I have one on my bike and it is a god send!

http://www.motosport.com/offroad/product/TURNER-FUEL-MIXTURE-SCREW/?prodId=779084&sMMY=&cat0=

The extra jets that come with your bike allow you to rejet for conditions that vary a great deal from sea level or standard temps.

The emission comment from your dealer is the biggest BS I've ever heard. Your bike is a race bike it's exempt from emission standards in all 50 states!

 

[yz250rac3r]

wow definitly nice to know that the dealership was retarded
thanks for the link will definitly invest in fuel screw if you like yours so much
otherwise i really appreiciate all the help

 

[crazycarl7]

thanks for clarifying the adjustable fuel screw extention. Like I said before it is importsnt to have. Half a turn one way or another makes a big difference?

 

[_JOE_]

My honda was quite lean stock. Try one size and see if what happens. It WILL NOT hurt any thing. Might not make it run better though.