Rebuild Time???????????


8 replies to this topic
  • vwdubs

Posted July 31, 2005 - 09:31 PM

#1

99 yz400 here are the sympthoms
high idle, it does not get affected by idle screw
could get it turned on like a two stroke without much effort
smells like its burning oil
after running for a while it started to puff out white smoke out of engine vent hose and afterwards it started to leak a little oil thru the same hose

other than that the bike runs fine but it smells like s**t, high idle but it doesnt semm to have a power loss (not that i would be able to tell the difference i bought it used about three weeks ago and never ridden a 400 before only 250) its just pretty fast.

so is it time to replace piston and rings or it couls be something else :D

  • MotoGoalie

Posted August 01, 2005 - 07:05 AM

#2

Sounds like you need to tear it down and do some work....

  • biznet1

Posted August 01, 2005 - 10:21 AM

#3

You could do some testing (compression/leakdown) without tearing it down just yet. Also, old gas and sitting for a while will produce some of those symptoms (the smell particularly), since you've rode it some, I assume you've been through a tank already though.

  • chadwic82

Posted August 01, 2005 - 04:36 PM

#4

rebuild time. My 99 YZ400F did exactly the same things yours is doing & I had to have it rebuilt. $850 bucks later it was fixed

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  • vwdubs

Posted August 01, 2005 - 08:36 PM

#5

thank you guys i'm tearing it down as we speak :D

  • vwdubs

Posted August 02, 2005 - 05:52 PM

#6

here is what i found
piston is good
oil ring is not
oil is not milky however the is no coolant, where did it go?????

so it overheated and fried the ring but where did the coolant go

  • MotoGoalie

Posted August 03, 2005 - 06:24 AM

#7

here is what i found
piston is good
oil ring is not
oil is not milky however the is no coolant, where did it go?????

so it overheated and fried the ring but where did the coolant go


Have you popped open the clutch side of the case?

  • vwdubs

Posted August 03, 2005 - 07:54 PM

#8

yes changing water pump seals and shaft they are bad (more like melted and the shaft is f*****d)

  • vwdubs

Posted August 25, 2005 - 12:43 PM

#9

the bike was put all back together and i still have little compression however it runs good do i have to wait till the rings seat to do the compression test





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