oil behind flywheel cover

6 replies to this topic
  • #302

Posted June 29, 2002 - 08:34 AM


my older brother recently purchased a 98 yz400. Yesterday i inspected the valves to be on the safe side. The valves needed to be adjusted so i a began disassembling the motor. I began removing the two caps on the flywheel cover to position the motor at top dead center. When i removed the caps motor oil started pouring from the lower opening. The motor runs fine and there is no apparent problem with the performance. When i adjusted the vavles on my '99 i didn't have oil dripping from these openings. If anybody has any info that would help me out it would be appreciated.


Posted June 29, 2002 - 10:56 AM


302, there should be some oil inside the flywheel cover, the cam chain slings it around in there and gets some of it's lube from there and the top-end, so having oil inside is common it's supposed to be there, now if it was running out of the hole???dunno, maybe someone poured some in there in an attempt to fill it up???, i would drain and re-fill to proper capacity????jimbo

[ June 29, 2002: Message edited by: RIDEPATE ]

  • #302

Posted June 29, 2002 - 02:10 PM


forgot to mention, the bike was sitting for 2-3 months with very periodic starts.

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  • YZ400Court

Posted June 29, 2002 - 04:48 PM


The oil will drain down there if the bike sits. As soon as it is started it gets pumped back into the oil tank. Always start it first.

  • freestyle111

Posted June 29, 2002 - 10:47 PM


yamaha 4strokes arent like 2 stroke with sealed flywheel.oil is supposed to flow on both sides of motor

  • Mark_Cantrell

Posted June 30, 2002 - 12:47 AM


yz400court has it right. If you take out the center screw where you turn the crank with a 14mm wrench, it will normally be dry. Let it sit and in a day or two, oil will start dripping out of it, especially WR's on the kickstand. The oil from the frame reservoir is leaking down into the crankcase, the flywheel is open to the crank, and the oil drips. Start it up and the scavenge pump pulls it right back up to the frame reservoir. Same reason you have to start it to check the oil.

Good luck,

  • #302

Posted June 30, 2002 - 04:47 PM


thanks for the info guys. When ever i run across something i'm not sure of, the fine people here on thumpertalk always guide me.

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