Leak Jets

[Thesykboy]

Can anyone tell me why I can't find a leak jet on any schematic I look at for my carb? I've looked at multiple shops online and walked into a couple to ask the parts guys... They either say that my bike (03 wr450) doesn't have a leak jet (which it clearly does) or that it's not listed since Yamaha didn't want you messing with it (sounds like crap to me).

I've pulled the leak jet, seen that it has a size number on it (like any replaceable jet does), but after looking at schematics for 2002 WR426 through 2007 WR450, none of them point out an upgradeable leak jet! ?

Why would that be?

[FORMA MOTO]

Can anyone tell me why I can't find a leak jet on any schematic I look at for my carb? I've looked at multiple shops online and walked into a couple to ask the parts guys... They either say that my bike (03 wr450) doesn't have a leak jet (which it clearly does) or that it's not listed since Yamaha didn't want you messing with it (sounds like crap to me).

I've pulled the leak jet, seen that it has a size number on it (like any replaceable jet does), but after looking at schematics for 2002 WR426 through 2007 WR450, none of them point out an upgradeable leak jet! ?

Why would that be?

What difference does it make? Put a 50 in and be done with it.

They don't list the Air jet, the Needle jet, the Power jet, the Slide version, the vacuum plate version, etc etc, either.

You do realize that Yamaha does not make that carb. You would go to a Keihin sight to get more info (www.sudco.com).

[ur2silly]

Take a look at this link. It's for a 2005 yz450f. Item#22 on the parts diagram is the leak jet. I believe the YZ and the WR (2003-2006) use the same carburetor but the YZ diagram lists the part numbers for different size leak jets. Someone please correct me if I am wrong about these two bikes/years using the same carb

http://www.ronayers.com/Fiche/TypeID/26/Type/Motorcycle/MakeID/4/Make/Yamaha/YearID/46/Year/2005/ModelID/1793/Model/YZ450FT_YZ450F/GroupID/340129/Group/CARBURETOR_

Edited October 25, 2011 by ur2silly
spelling

[FORMA MOTO]

Take a look at this link. It's for a 2005 yz450f. Item#22 on the parts diagram is the leak jet. I believe the YZ and the WR (2003-2006) use the same carburetor but the YZ diagram lists the part numbers for different size leak jets. Someone please correct me if I am wrong about these two bikes using the same carb

http://www.ronayers.com/Fiche/TypeID/26/Type/Motorcycle/MakeID/4/Make/Yamaha/YearID/46/Year/2005/ModelID/1793/Model/YZ450FT_YZ450F/GroupID/340129/Group/CARBURETOR_

You are wrong, but not wrong. Same body, different set up.

The WR fiche also show the leak jet~! It's positioned in a strange place as wall, in the exploded diagram, # 20

http://www.bikebandit.com/houseofmotorcycles/2007-yamaha-wr450f-wr450fw/o/m18998#sch644861

[ur2silly]

Kranny, I believe #22 in your diagram is the leak jet and #20 is the ??? jet?

When I was jetting my bike I used the yamaha part numbers that I found on that site, except they were for a 2008 YZ450.

They were a perfect fit in my 2007 WR450 carb and yielded excellent results. The YZ diagrams listed the part numbers for the different sizes available for the jets where as the WR diagrams did not. I also used a stock YZ needle.

Perhaps older YZs and WRs carbs were a little different. I guess one could compare the part numbers between YZ/WR and if they are the same part numbers except for the last four numbers (which designates the size) then they are the same jet.

I believe Theskyboy asked his question because he wanted to be able to see the leak jet in a diagram. As far as I can see all the diagrams for the YZ/WR 450s are almost identical and a good representation of the FCR carb. However, none of them I have found show the leak jet where it actually lives.