Is it possible to change main/pilot jet w/o removing carb?

4 replies to this topic
  • rkwfxd1

Posted November 26, 2009 - 12:07 PM


On a 07-09 model WR450?

By the looks of it this is probably a stupid question but invariable some one on this board has figured out a way to do the impossible. So...

Is it possible to change the main and hopefully the pilot jet without completely tearing the bike down and removing the carb? If so, how did you do it, what tools did you use?


  • SXP

Posted November 26, 2009 - 12:28 PM


Yes, I've done it. I used a mirror (and shop light pointed at the mirror) to accomplish it. It was frustrating and slow work and and I dropped the jets so often that I almost decided to do it the right/long way, but persevered and succeeded in the end. Put a paper towel down under the carb to catch the damn jets when they fall or you will spend a lot of time looking for them.

- 19 mm wrench for float bowl plug
- 1/4 inch drive ratchet with appropriate size socket for the main jet
- 2" long flat blade hexagonal bit with a ratcheting closed-end wrench (or some other means to turn the bit) for the pilot
- Mirror
- Light
- Paper towel

It may also help to lay the bike on it's side so you don't have to bend your head at an impossible angle when trying to look up the float bowl hole.

Good luck.

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  • tribalbc

Posted November 26, 2009 - 12:43 PM


Main is easy enough to just fish a socket in there.
The pilot you can either do the mirror technique as SXP suggested or...

Remove seat
Remove 2 bottom subframe bolts and loosen top one
Loosen airbox boot clamp and swing subframe up out of way and tie off to handlebars.
Loosen intake boot
Partially remove carb from boot and twist carb bottom towards ignition side of bike
You will now have the carb twisted enough to get at pilot with ease

Remove top bolt on subframe on reassembly so you can push the airbox boot properly on the carb.

  • rkwfxd1

Posted November 26, 2009 - 12:59 PM


Thank you gentlemen.

  • Krannie McKranface

Posted November 26, 2009 - 02:07 PM


If you rotate the carb, and use a tire iron or similar as a lever to move the carb even more as you access the bottom of the carb, you can do it in minutes.

Leaning the bike on it's side makes it even easier.
Put a nice big shop rag under the carb to catch jets, screws, vent brackets, etc.


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