Help - Oil Loss!

6 replies to this topic
  • 426_Pilot

Posted February 23, 2002 - 06:16 PM


I'm either burning or losing oil and don't know why. When I put the bike on a stand it drips oil from the thick black tube that's routed down the left side of the frame (after riding, engine hot). When I check the oil after filling and then riding I can't believe how much I've lost. Has anyone experienced this? What the hell is the problem? The bike runs great so I'm very confused. And no, I don't run it with low oil. Thanks for the help.

  • YZ400Court

Posted February 23, 2002 - 06:56 PM


Are you checking the oil AFTER warming the engine up in the morning?

  • SkinSF

Posted February 23, 2002 - 07:14 PM


Sounds like you over filled the oil

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  • Boit

Posted February 23, 2002 - 08:19 PM


That hose is the same as the PCV system on an automobile. When the piston goes down, it causes pressure to build in the crankcase which must be vented. Conversely, when the piston goes up there is a corresponding vacuum in the crankcase. If you check the end of this hose when the engine is idling, you can feel with your finger the two pulses. You might want to investigate if you are experiencing excessive crankcase pressure and what is causing it. Make sure this hose is not kinked by either improper routing, or if it's zip tied too tight to the frame.

  • 426_Pilot

Posted February 24, 2002 - 01:47 PM


I always check the oil and it doesn't register on the stick, so I add oil until it does. Then after the ride I'll check it again and it's down. I'm confused.

  • YZ400Court

Posted February 24, 2002 - 05:01 PM


One more time, do you warm the bike up prior to checking the oil. If you check it cold it will be low, as it is a dry sump system. The oil migrates down from the top tube to the engine when the bike is not running. Start the bike, let it idle for 3 or 4 min on a stand (level). Then shut off the bike and check the oil.

  • Guest_Guest_*

Posted February 24, 2002 - 07:03 PM


I change my oil after every-single race and once race season starts I also change it after a week of practice b4 a race. 1500ml and have NEVER lost a drop of oil nor has it been low.
Even after warmin my bike up for 3-4min it shows low but after 5-10min and get hot it shows FULL!
Make sure you give your ride plenty of time to warm up so the oil will expand and also work its way back into the resevoir (FRAME) It should check out fine then.
If not you should either have a black smoke pouring out of the back end of your 4STROKE or a wet spot in your garage!!!! (Not on that Yamaha BIKINI TEAM poster.......on your floor beneath the 400/426!!!) :) :D :D

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