Jump to content
Sign in to follow this  

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

Recommended Posts

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...

:)

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By BDTRENT
      Selling an FMF Power Core 4 exhaust system off my 450FX. Exhaust has 80 hours and is 100% functional. This will also fit the 14-15 YZ450F and 16-18 Wr450F. If needed I can also include new muffler packing although it does not need it. 
    • By Woody Oakson
      I have a 2008 YZ450F with a stock header pipe and Pro Circuit T-4 Slip-On Exhaust. I'm 99% sure the slip on is shot because its loud as hell and when I take it off and shake it it rattles. I would repack it but the screws are all stripped ect.
      Anyways I've gone over the carb multiple times and I've got it running pretty well. The only issue I have with the bike is that it sputters and pops around 1/2 throttle when I hold it there. When I give it full throttle from any RPM it runs great or when I give it about 3/4 throttle it spins up like a top to redline.
      Initially the popping and sputtering was way worse I made the situation better by moving the pilot jet up in a few sizes from a 45 (stock) to a 62. The issue has gotten way better since then but I'm not super sure what to do from here. Should I keep moving my pilot jet up in size because that's a pretty large jump right? I tried changing my needle clip position but that didn't help much if anything it just made starting it worse and little to no impact on the ride.
      Any input on this would be helpful. I don't want to buy other slip on. Also as for the rest of the carb I'm very sure everything else in it is what it needs to be at. I've replaced all the gaskets and O-rings cleaned all the jets, valve holes ect. fixed the accelerator pump timing. I just thinks its strange that my pilot jet size is going so far from the stock 45, but all symptoms point to the bike running lean.
    • By Haydenbaha
      Hi I was wondering if y’all have been using a 450 on your YZ250F?
    • By RockerYZWR
      Excel Takasago 17x3 front and 17x5 rear supermoto wheels with Metzler M3 tires in very lightly used condition. Less than 200 miles total on the setup. Warp 9 spokes. Rear has a Talon hub with 45T Sunstar steel sprocket and OEM rear disc, and front has a polished OEM Yamaha WR450F hub (for the stock speedometer), with a Motomaster 320mm disc. Included is a DID gold o-ring chain, 14T front sprocket, and front brake caliper adapter for a truly turn key setup. Everything is in excellent condition, not a single scratch on these wheels. Came off my '11 WR450F, but will fit many different Yamahas with 20mm front and 22mm rear axles. Asking $1400 plus shipping.
      **Will be driving up near Atlanta, then to northern Louisiana, OKC, and down through Dallas and Houston, TX soon -- can meet or deliver if in the area (Aug 31-Sep 9)**
    • By YZ426fNC
      Hi I’m new on the forum and I was wondering if a 2001 Yamaha YZ426f clutch is interchangeable with a 2002 Yamaha YZ426f clutch thanks , Coleman
×