Re Jetting question

I have owned a UK wr450f 07 since new, I have opened out the air box, and installed a Dep S7 full system exhaust. I have removed the AIS and grey wire.

I have spoke to my dealer about re-jetting and he said I will be fine with the stock jets? He said when they are imported over here they are re-jetted to suit.

Is this correct or am I doing my bike harm? it runs fine and has released alot more power.

I have owned a UK wr450f 07 since new, I have opened out the air box, and installed a Dep S7 full system exhaust. I have removed the AIS and grey wire.

I have spoke to my dealer about re-jetting and he said I will be fine with the stock jets? He said when they are imported over here they are re-jetted to suit.

Is this correct or am I doing my bike harm? it runs fine and has released alot more power.

Find out for yourself.

According to my 2003 WR manual, the jetting is only slightly different for different contenent, as is still WAY too lean for the modifications you have made, and you need to re-jet. You can buy a jet kit from JD or Dyno jet. It will take you a couple of hours to install.

Verfiy what size mian jet you have fitted

Should be around 168

If 160 its too lean, and 175 its too rich

160 is std in the UK, 175 is supplied in a little bag for the owner to fit

Your Dealer, like every other dealer, knows nothing. Buy a jet kit and it will be one of the best investments for your WR.

Cheers Guys,

Can anybody tell me what size I need to be looking at for a UK bike with the mentioned mods.

Cheers

Use the stock carb specs for the 2004 WR450F USA model. I've used this spec for my 2006 and 2008 WR450F with great results -- you too will be happy. You can find them at the Yamaha Australia or Europe websites under owners' manuals. However here they are (only differences between USA and Europe models noted):

Carburetor:

USA EUROPE

MJ 165 160

JN OBDWR-4 OBDUQ-4 (NUMBER IS CLIP POSITON)

PJ 45 48

PAJ 70 80

PS 1-3/4 1-1/2 (FUEL/AIR SCREW)

Acc.P 60 50

The layout doesn't work too well, but you get the idea. This jetting works well from sea level to 5,000+ft and I regularly achieve 30-40 MPG, depending on trail/road conditions.

Would I be ok with a jd jet kit, does anybody know?

also should I need to tweak with the acceleration pump?

Yes, and only you will know about the acc pump. After installing the JD kit, if it bogs off idle, then you should check and adjust the acc pump.

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