How to remove Needle Vavle and Seat?

29 replies to this topic
  • Mrmonk7663

Posted December 29, 2009 - 04:18 PM


Can anyone tell me how to remove this stuff? I have the carb in hand, just dont know what to do with these parts. They are gummed up and I need to clean them. FYI....Yamaha has no part number for a valve seat or the viton o ring or the fuel screen...only the needle valve. Sudco has part numbers for them though.

How do you know if your needle valve and seat are bad?


  • Treebark

Posted December 29, 2009 - 10:43 PM


I am assuming you are talking about the float needle and seat? The pin holds it all together you just need to push it to one side or the other. They don't normally go bad unless mishandled or overly aged and sitting in fuel for long periods of time. Don't loose the retainer spring attached to float and needle. Do not scrap the rubber tip as this will cause leakage and flooding problems. Also do not bend the little tab on the float as this will cause a incorrect float level. I would recommend to leave the seat(part mounted to the carb body itself) in place to clean.

  • Treebark

Posted December 29, 2009 - 10:47 PM


Forgot to tell you how to check. If you leave everything in place hold carb vertical and connect fuel line, no fuel should pass through the needle valve and seat if the float is lifted.

  • Mrmonk7663

Posted December 29, 2009 - 10:56 PM


Thanks for the reply. What pin are u talking about? Right now float and bowl are off. I'm looking at the float needle valve and retainig clip. The valve needle has a little ball that u can press...doesn't look rubber to me. I see no rubber. But anyway I don't see how to take the needle valve out and yes it has sat in bad gas a long time. Thanks

  • Treebark

Posted December 29, 2009 - 10:59 PM


The needle is stuck in the body portion of the carb???

  • Mrmonk7663

Posted December 29, 2009 - 11:30 PM


Oh u mean the big fuel needle with the c clip on it lol. So if I remove the needle I should be able to simply pull the float needle out?

  • Treebark

Posted December 29, 2009 - 11:38 PM


NO LOL. The needle must be stuck in the body. The ball you speak of? is where the retaining clip connects to?

  • Mrmonk7663

Posted December 29, 2009 - 11:45 PM


Yes. The ball is where the float retaining clip is attached to..around the ball. So the needle should just pop right out is what ur saying? Nothing holds the needle valve in the valve seat? If that's the case I'll yank it out with pliers and buy a new one. ???

  • Treebark

Posted December 30, 2009 - 12:30 AM


Yes, that is what I meant. I was trying to figure out what situation you were having. You can pull with pliers and get a new one. Make sure it comes out with the rubber tip attached otherwise before you re-install new needle the seat needs to be cleaned. Any uneven surface will cause fuel to leak by.

  • Mrmonk7663

Posted December 30, 2009 - 12:40 AM


Sounds good. What is this rubber tip? Is it a part of the needle or a separate piece? Are u talking about the o ring under the seat? Oh and thanks for all the help and sorry for all the confusion haha. Hard diagnosing via iPhone

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  • Mrmonk7663

Posted December 30, 2009 - 05:39 AM


Ok, I just pulled out the needle valve. It was stuck in there good. How freely should this part come out...should it basically fall out when all is clean? I can now blow air through the fuel tube freely, so the needle valve was the part that was sealing all air flow. The needle valve was not letting fuel into my bowl. A rubber piece was mentioned and I was warned to make sure it comes out...i'm still not understanding what rubber piece this is...where is it located? Should I need to replace the valve seat and 0 ring or are these parts most likely fine? The needle valve is gummed to hell and the seat is gummy too...I will replace the needle for sure but need guidance on the seat and o ring and fuel screen. Thanks.

  • WholeShotKing

Posted December 30, 2009 - 07:05 AM


The fuel Needle valve should simply fall out with no effort other then gravity. If it is stuck, as your is, then I would:
1. Hold the carb upside down and spray WD40 in the fuel needle valve brass fitting.
2. Let it sit for a while and then flip the carb right side up.
3. If the Needle does not fall out, spray WD40 in the fuel input fitting where the fuel line goes and wait a while. Pull it out with needle nose pliers.

The rubber everyone is talking about is on the very tip of the fuel needle valve. The mating surface on the needle comes to a point. (Hence the name needle valve) The point is made of rubber. (typically)

Once removed, clean the fuel needle valve completely, (I use WD40 and a soft rag so I don't damage the rubber tip) The other end of the fuel needle valve has a spring plunger. Make sure the plunger moves freely as they can become gummed up too.

Use a Q-Tip and WD40 to clean the brass fuel needle valve seat. Keep using new Q-Tips until clean.

To stop this from happening in the future:
1. Ensure your fuel petcock turns off completely. If not, replace the rubber insert.
2. Drain the fuel from the carb using the small allen screw on the float bowl.

Look at and adjust the float height as defined in their carm adjustment manual.

  • Mrmonk7663

Posted December 30, 2009 - 07:35 AM


Thanks for that info, its just what I needed. I got the valve out with pliers. I will clean the seat as you said. I am just going to order a new valve, I have to order new fuel vent lines anyway so I'll get that and the vavle at the same time. And the rubber piece came out when I pulled the needle valve out :-) I'll be back in business soon I hope haha. And yah, I think the major problem was my wouldnt turn off all the way....A new one is on its way already too. Thanks for all the help guys!!!

  • Mrmonk7663

Posted December 30, 2009 - 07:42 AM


One last thing....should I leave the valve seat in the carb or remove it to clean it? If I should remove do I do that?

  • l_campionero

Posted December 30, 2009 - 07:56 AM


The rubber tip is the black part in this photo:

Posted Image

  • Mrmonk7663

Posted December 30, 2009 - 08:14 AM


ok, definitely got that my valve looks like horse poop compared to that haha. Now about the valve seat... :-)???

  • WR_Dave

Posted December 30, 2009 - 01:57 PM


On the earlier FCR carbs , you could remove the seat to replace the rubber O-ring that started to leak every few years. The newer ones don't have the removable seat so use this guide to help you and pay special attention to step 15. WR Dave


  • Mrmonk7663

Posted December 30, 2009 - 04:44 PM


My bike is an 04 WR450, so I believe this is a generation II carb that you can remove the valve seat from, and the parts diagrahm confirm this. I can't see any fuel screen. My valve seat is gummed beyond help and the oring is probally jacked. I need to remove the valve seat but don't know how.

  • WR_Dave

Posted December 30, 2009 - 06:14 PM


If you have the removeable float needle valve seat then there should be a washer headed screw that just comes over the edge of the seat to hold it in place. WR Dave

  • Mrmonk7663

Posted December 30, 2009 - 06:48 PM


Ok, here is a photo. I'm lost. Posted Image


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