My WR400F leaks oil and gasoline

5 replies to this topic
  • shootking

Posted July 29, 2010 - 05:30 AM


I have just bougt an Yamaha WR400F 1999 from my brother. It has been around for 10 years and is not any near new anymore... But it is a functional beginners bike and suits me well.

I have two things I hope to get help with from the TT forum...

1. When I turn on my fuel cock my carburetor begins to drip gas. What could be wrong?

2. I have some oil leakage from the drive axle (where my front sprocket is attached). What is the part number of this gasket that I need to replace? I can´t find any good schematics over this side of the motor...

Regards Jens

  • ncampion

Posted July 29, 2010 - 06:12 AM


Those are good bikes, have one myself with a zillion miles on it and still going strong. The fuel leagake is most likely the float needle. Replace it, you can't repair it. Try this link for parts lists and for buying on line.

Good luck


  • matt4x4

Posted July 29, 2010 - 06:16 AM


Fuel leak - sticking or worn needle valve or float - since the bike sat, the needle valve could have dried out or be dirty with varnish (bad dried gas).
Clean your carb first and try it again, if it's still leaking, you might need to buy a needle valve.

Oil leak - if you go to teh dealership tehy can look it up, but any on line OEM supplier has Microfiche's available for parts lookup.

Carb diagram: http://webservices.m.../CARBURETOR.Gif

Tranny Diagram: http://webservices.m...RANSMISSION.Gif

Parts 25, 26 and 27 will need to be replaced

To get part numbers, here's one of many sites:

Also - it sounds like you could use a manual :

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • shootking

Posted July 30, 2010 - 12:48 AM


Thanks for the advice! I have cleaned carburetors before, but not in any way as advanced as this one... It's like a zillion parts!

Any advice on how much disassembling I have to do? Which places in the carb is most likely clogged with dirt?

  • julleman

Posted July 30, 2010 - 01:30 PM


Hey Jens!

You can look at for information how to do! Also check your Yamaha part at or similar sites for partnumber to spareparts.
Sounds like your machine needs a total checkup...

  • shootking

Posted July 31, 2010 - 11:16 PM


I have seen the guide on SOE. And you are probably right about my machine, it needs a total checkup...


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