Carb leaking

11 replies to this topic
  • Yamiryder

Posted March 19, 2012 - 05:25 PM


My 07 yz450 is leaking gas out of the carb when it shouldn't. When running, when the bike gets at any sort of angle out of normal, gas leaks out the drain hose. Also, when i got the bike at steep angles, it occasionally stalls. Is this a float sticking or something? I'm not too good with carbs....any help is appreciated. :thumbsup:

  • bullwinkle289

Posted March 19, 2012 - 11:01 PM


I had something similar, all I done was remove the plug from the base of the carb, let the small amount of fuel drain out and replace the more fuel leaking from the drain hose.
I had the tank off before the leak started, all I can think of is that maybe some dirt got in from wherever I'd set the tank down and blocked something up a bit. I'd open the fuel tap and a second later it would be running out the drain hose.

Hope this helps!

  • Yamiryder

Posted March 20, 2012 - 02:34 PM


Hmmm, i did have the tank off. I'll go try that. For some reason i don't think i'll be that lucky though...

Edit: i just did what you said to do, and took my bike for a ride around the yard. Still leaking bad like before. Guess its time to tear into the carb.

Edited by Yamiryder, March 20, 2012 - 03:34 PM.

  • TeamPrecisionIT

Posted March 21, 2012 - 05:09 AM


Most likely you have a bit of grit or gunk causing the float valve not to properly seat which would shut off the flow of gas into the carb. I had the same problem on my 03. There was just a little bit of varnish/gunk on the float valve and even if I just turned the gas on and not have the bike running, it would leak. Give that a shot and see if it fixes your issue.


  • Yamiryder

Posted March 23, 2012 - 06:40 PM


Well, i dropped the bowl on my bike yesterday and sprayed some carb cleaner to clean it up. Put it back on today and rode the bike, still is leaking some gas. It only seems to do it when the bike gets at angles like a wheelie or over any sort of jump....

  • grayracer513

Posted March 23, 2012 - 10:47 PM


Sounds like the float level is too high. If this condition appeared after you worked on the carb, you may have bent the float. If it show up without any interference on your part, one of the floats might be leaking.

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  • Yamiryder

Posted March 24, 2012 - 06:55 AM


Ok, it started happening when i was riding last weekend, so its probably the latter.

  • Chas_M

Posted March 25, 2012 - 06:14 AM


Another possibility is a bad O-ring that seals the float needle seat. These O-rings commonly harden and deteriorate with age and start leaking. These are available individually as a replacement part from your Yamaha dealer.

  • Yamiryder

Posted March 25, 2012 - 09:42 AM


Another possibility is a bad O-ring that seals the float needle seat. These O-rings commonly harden and deteriorate with age and start leaking. These are available individually as a replacement part from your Yamaha dealer.

I thought of that, but it only leaks when the bike is running, so i'm leaning towards the float being the problem.

  • Yamiryder

Posted April 15, 2012 - 04:32 PM


well, i'm bringing this thread back to try to get some more advice. I adjusted my float, and that helped my bike for a couple hours of run time. However, When i rode today, my carb started leaking again and it will stall when not under throttle in uphill and downhill situations. Do i need to replace my float and plunger? what else can be wrong?

  • grayracer513

Posted April 15, 2012 - 07:09 PM


Put the float in a cup of gas. If it floats at the same level on both sides, it's probably OK. The float needle and seat are probably bad.

  • Yamiryder

Posted April 16, 2012 - 02:03 PM


Ok thanks, i'll try that. :thumbsup:

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