Carb Question

The carb in an '06 WR450 has more jets than I'm used to

In a 'traditional' carb you have:


Main Jet

Needle / Needle Jet

Pilot Jet

Pilot air screw


In addition to the above, it seems this carb has


1) A 'Leak' jet that seems to tie in with the accelerator pump


2) It has a Pilot Jet & a Pilot Air Jet.....and no adjustable 'pilot air screw'


so the air screw is replaced with a fixed orrifice or jet


Is this all correct?

I also see mention of a 'fuel screw' in the carb settting section on this site

I have scoured the manual and I do not see a fuel screw on my carb

Is this a mis-print or do earlier carbs have a fuel screw?

Some good reading here


It's for the YFZ quad which has almost the same engine as the WR, but I'd imagine the jetting is slightly different.  Functionally the same though.  Read that to understand it, then come back to the jetting threads here.


My 2005 WR450 (Aus) had the fuel screw blanked off for emissions reasons - it's still there you just can't get to it without removing the float bowl.  I installed an aftermarket fuel screw so it can be adjusted by hand while on the bike, simple and cheap mod.

Edited by eRRmmm

Those are two great links, thanks !!!!

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