Fuel Screw Washer and O-Ring


16 replies to this topic
  • mcnaughb

Posted February 21, 2008 - 08:49 PM

#1

On a recent ride, my aftermarket fuel screw fell out and my bike (06 450) started running horrible. I look down and find the screw lying on the case, with the spring. So I clean it off and put it back in. Things are working normal.

Is it possible that I lost the little washer and o-ring and the bike still runs OK?

I find it hard to believe that it would have stayed in with the motor running and me riding.

Thanks.

  • 426boy

Posted February 21, 2008 - 08:59 PM

#2

i would say pull the fuel screw out and see if the washer and o ring is in there, if they are not i would get some new ones.

  • grayracer513

Posted February 21, 2008 - 09:02 PM

#3

The O-ring could have stayed stuck, and so, actually could the washer, but the spring is almost certainly gone, and the O-ring would be all that is holding it in now. You need to find a spring.

  • djtroy

Posted February 21, 2008 - 09:11 PM

#4

The O-ring could have stayed stuck, and so, actually could the washer, but the spring is almost certainly gone, and the O-ring would be all that is holding it in now. You need to find a spring.


I think he said he had the spring and the screw. The O ring gets wedged in there pretty good. I used a bent paper clip to scrape mine out. Try that and see if it comes out.

  • mcnaughb

Posted February 21, 2008 - 10:26 PM

#5

Yeah, the spring was there. I was hoping to avoid going through the efforts of removing the motor mounts, etc to get the carb tipped out enough to be able to get at it. Just lazy. :smirk:

Guess I'll have to now. Bummer.

Thanks.

  • rexbond007

Posted February 21, 2008 - 10:54 PM

#6

the o ring could still be up inside the carb take a look?

  • Racegun

Posted February 21, 2008 - 11:57 PM

#7

i just use a mirror to look up mine , just shine a torch on the mirror, i can see if my orings in there or not no problem

  • yz_for_me

Posted February 22, 2008 - 12:26 AM

#8

I know it will run without the o-ring. When I first got my 426 I didn't even know it had an o-ring until I read about it on TT. I rode in ignorance without one for several months. The previous owner had lost it before I bought the bike.

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  • William1

Posted February 22, 2008 - 04:20 AM

#9

FYI, I use a second O-Ring on my extended Kouba screw. It has a few O-Ring grooves in mid shaft. I drilled the float bowl (removed from the carb, of course) to .256" also. I put the second O-Ring in one of these secondary grooves. Serves two purposes. One, to provide additional friction to the screw to prevent vibrating out, Two, to 'seal' the threaded portion of the sreecw to prevent debris from giving me grief.

  • maddogyz250f

Posted February 22, 2008 - 08:04 AM

#10

FYI, I use a second O-Ring on my extended Kouba screw. It has a few O-Ring grooves in mid shaft. I drilled the float bowl (removed from the carb, of course) to .256" also. I put the second O-Ring in one of these secondary grooves. Serves two purposes. One, to provide additional friction to the screw to prevent vibrating out, Two, to 'seal' the threaded portion of the sreecw to prevent debris from giving me grief.



Awesome idea.

  • grayracer513

Posted February 22, 2008 - 09:29 AM

#11

Yeah, the spring was there. I was hoping to avoid going through the efforts of removing the motor mounts, etc to get the carb tipped out enough to be able to get at it. Just lazy. :smirk:

Guess I'll have to now. Bummer.

Thanks.

You don't need to move the carb. Use a bent paper clip as suggested earlier. The bend has to be very short, so you'll want to bend it and then grind it down some.

Another clue is that if the O-ring is there, you will be able to stick the screw (without the spring) in place without threading it and have it stay there.

Are you using an aftermarket extended screw?

  • mcnaughb

Posted February 22, 2008 - 11:10 AM

#12

Yes, an aftermarket screw. The screw has an additional groove for a "friction" oring, but the oring failed, that's why it fell out to begin with.

I'll try the mirror and paperclip trick.

  • grayracer513

Posted February 22, 2008 - 12:05 PM

#13

One thing I have found with some of the AM screws is that the springs they ship with, if any, are often not strong enough to keep the screw in. I reused the OEM spring on both mine.

  • ben_suhard

Posted February 23, 2008 - 01:25 AM

#14

If you keep having trouble with the fuel screw coming out, you could drill a small hole through the head and safety wire it; it would make it a bit of a pain to adjust, but at least you won't lose it!

  • kwb

Posted February 28, 2008 - 01:36 AM

#15

I have an 08 yz450 also and my after market fuel screw keeps backing out. It came with a small O-ring and I reused the stock spring. I looked in the schematic for the carburator and it shows a flat washer, o-ring and the spring. I seem to be missing the flat washer and o-ring. I bought the bike new.... Not sure why it is missing - I took a mirror and light as suggested and looked up the carb opening and dont see it stuck up there. :smirk:

  • grayracer513

Posted February 28, 2008 - 07:55 AM

#16

You probably wouldn't see it if the flat washer is stuck on it. Push the screw into place without the spring as far as it will go without threading it in. Does it stay? If so, the O-ring is still there.

If they are in fact missing, you can now buy them individually:

3TJ-14562-40-00 O-RING
3TJ-14952-40-00 WASHER
3TJ-14160-40-00 COIL, SPRING

  • mxraymond65

Posted March 01, 2009 - 07:50 PM

#17

I have had the same problem with the fuel screw falling out of my 07 YZ450F I quick remedy is to scribe a line through the threads on the fuel screw to add resistance to backing out. R&D makes a fuel screw adjustment system called Flex-Jet. Its pretty much impossible for it to fall out.

If your fuel screw falls out while riding plug the hole in the bottom of your carb. I balled up a little piece of electrical tape to get me back to the truck. runs rich but better than an air leak!





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