Changing your needle jet, needle clip and/or pilot jet

I posted this on the WR400 forum and thought it might be useful here too (as per Chris's request).

The needle jet is accessible through the top of the carb. You don't need to remove the carb to get to it.

Loosen the front and back clamps that hold the carb secure so it can rotate, remove the gas tank hose, remove the throttle cable cover and throttle cables (easy to adjust throttle cable once you've done it), and rotate the carb as best you can so you can get to the top. To do so you also have to remove one more hose attached to the carb. When you take the cover off, you need an allen wrench to undo the needle holder. At this point, the needle slides up and out.

It is tight but not too awful bad.

Now that you have the needle out, you can change the clip position. The stock WR clip is 3 from the top, stock YZ is 4 from the top. Someone can post a reply to this and tell us what the stock YZ426 is set at.

Now, getting to the pilot jet is a little more difficult. But, not a lot more difficult.

It is located at the bottom of the carb. So, you have to figure out what else you need to remove to get the carb to rotate the opposite direction. I think I had to remove the float bowl drain plug (I'm used to that since I rejet often here in Colorado), and maybe one more hose.

You must then remove the float bowl and then this little plastic retainer inside the bowl. Try and remember how the retainer comes off although it isn't to hard to figure out how it goes back on.

The pilot is located in one of the holes that is off-center. You will probably need to look in the manual to figure out which. If you can't figure it out and/or don't have a manual, let me know and I'll look in mine. Or, you can guess and take it out and see if it looks like your new one (duh!).

You need a small screwdriver to get into the hole to remove the pilot.

That's about it. Remember to clean and oil (don't over do it) your filter while your doing all this unpleasant crap so you can maximize your roost boost! (clever eh?)

Good luck,

Bryan...

:)

The standard jet needle grove on the YZ426 is 4th from the top. The carb on the 426 can rotate for access to the jets & pilot screw buy removing the allen bolts holding the coil, let it hang, and loosen the carb mount clamps. No need to take off any hoses.

Phil

'00 YZ426

'00 XR100

'98 300EX

'95 VFR750

The standard jet needle grove on the YZ426 is 4th from the top. The carb on the 426 can rotate for access to the jets & pilot screw buy removing the allen bolts holding the coil, let it hang, and loosen the carb mount clamps. No need to take off any hoses.

Phil

'00 YZ426

'00 XR100

'98 300EX

'95 VFR750

Are you sure the standard groove is 4th from the top? Because that's not what it says in my manual.

It is (#4 spot) for the 03, I believe. Say Bryan, can you post your tips in our Jetting thread above? That's fine advice.

Are you sure the standard groove is 4th from the top? Because that's not what it says in my manual.

I'm certain, on the '01 anyway, it's the #4 groove. Like YZFWrench said, it's very easy on a 426. Just remove your seat and gas tank-it makes it easier. Then loosen the front and back carb clamps. I know, I've done it about a million times! :D

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