650R:Stuck Carb Float Valve?


9 replies to this topic
  • thecirque

Posted August 13, 2006 - 09:12 PM

#1

:thumbsup: My bike started acting like the float valve was stuck open. It was dumping gas all over from the vent/overflow line. I noticed it running real rich, looked down and gas was dripping excessively from the vent tubes. It even ran out of the air cleaner side plate vent like it was backing up and coming out the intake. I took apart the carb, visually inspected and put back together there on the trail. It quit leaking so I figured problem fixed.

I started hammering down the trail and again, at my next stopping point, my bike looked like it was taking a piss from the carb overflow vent.

It seems that as long as I'm putting along (read: no fun) the bike works fine, but as soon as I hammer down, float valve sticks open and floods out the bike.

I'm going to replace all internal carb parts I think unless someone can help me out. What could be causing my problem?

Thanks in advance!!!

:ride:

  • thecirque

Posted August 14, 2006 - 09:57 AM

#2

ttt...someone help me out here? Pretty Please?

THanks.

  • SniperTeamBravo

Posted August 14, 2006 - 10:44 AM

#3

ttt...someone help me out here? Pretty Please?

THanks.


Is there a vacume line plugged or not connected? Id look at getting a new float valve assembly, then if the problem perssts, get a Keihin FCR41 kit! Dude, this is your excuse to power it up with a NEW Keihin carb kit!!! Hallaluja!

  • thecirque

Posted August 14, 2006 - 11:25 AM

#4

Hmm....I knew there was a reason I listened to your opinions on this forum. Buy more, buy bigger. What was I thinking.... Pumper Carb, here I come.

  • tirebiter

Posted August 14, 2006 - 11:46 AM

#5

Sounds like the float needle's stuck open. After you take the float & needle out, shoot some carb cleaner thru the needle seat, then follow up with some compressed air. Look for little bits of red plastic- if you see any, take off the petcock and check your fuel filter. Heck, take a look at the filter anyway, can't hurt..

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  • Old_Man_Time

Posted August 14, 2006 - 12:18 PM

#6

If your still running the XR650R stock carb then you need to reset the float level so that it shuts the fuel off 2mm sooner than what the stock specs say. The XR650R float is set up for Baja which is relatively flat running at high speeds. The bowl is filled to the maximum limit. So all that has to happen as the bike is ridden is for the float to go just a bit out of adjustment and wham you have the flooding situation you describe.

To illustrate this for yourself, take the carb off the bike and hook a fuel line to the carb and turn it on. After the float bowl is full start tipping the carb as if the bike were climbing a hill. Eventually the carb will start pissing out the back where it would empty into the air box. It might surprise you to see how little of an angle is necessary to cause it to overflow. Once it starts back flowing slowly tip the carb level. Again it should surprise you how close to level you have to be to stop the back flow.

Provided you do not have a piece of sand or grit stuck in the needle valve seat it is your float level causing the problem. Never set the float at factory specs. Some bikes get away with factory specs but none of the XR650Rs that I have worked on could keep the factory specs. We ride these bikes in mountainous woods areas.

  • SniperTeamBravo

Posted August 14, 2006 - 12:36 PM

#7

Hmm....I knew there was a reason I listened to your opinions on this forum. Buy more, buy bigger. What was I thinking.... Pumper Carb, here I come.


Anytime you want to up-grade something but can;'t figure out a way to justify it...Ill be happy to ablidge!

  • Old_Man_Time

Posted August 14, 2006 - 04:03 PM

#8

Is there a vacume line plugged or not connected? Id look at getting a new float valve assembly, then if the problem perssts, get a Keihin FCR41 kit! Dude, this is your excuse to power it up with a NEW Keihin carb kit!!! Hallaluja!


If you do decide to go with a pumper the Edelbrock Quicksilver is an easy switch and no more jets to mess with. The stock carb can be made to work and I would get yours working before making the switch. Pumpers are great but for some folks they are not worth the money. I switched to the Edelbrock and love it. My stock carb worked great but for me the benefits of the pumper were worth the money.

  • thecirque

Posted August 15, 2006 - 09:41 AM

#9

Tire Biter....Thank you very much. I'll will consult the service manual and see if I can reset the float bowl 2mm shy of stock specs as you suggested.

Is it possible that the little float plate that the valve rides on can get scored or worn enough to create enough friction that it would hang up and lock the float in the down position thereby not shutting off fuel into the carb?

  • tirebiter

Posted August 15, 2006 - 02:39 PM

#10

Is it possible that the little float plate that the valve rides on can get scored or worn enough to create enough friction that it would hang up and lock the float in the down position thereby not shutting off fuel into the carb?


Yes it can. You can buy the float needle & seat from your dealer, changed one on my buddys R last week. Simple process.
Try cleaning & float level adjustment first though.

Do you have a good factory service manual?? If not, here's where you can get one..
http://www.helminc.c...CDDSAT0UVKB62SC





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