YZ426 a lot of oil coming out of the valve cover breather?


9 replies to this topic
  • GVDRZ400SM

Posted April 03, 2015 - 12:49 PM

#1

What's up guys , my good friend has a yz426 in supermoto trim that rides with me . He bought it used from a guy , it was pretty much stock .

Previous owner had a 40 tooth rear sprocket and 16 tooth front to gear it up for the street . Gears were very long , after riding and leaving the bike overnight he would notice a drip or 2 of white/yellow oil residue on the floor dripping from the valve cover breather hose . Never thought it was any issue at all.

Now my friend geared it down for stunting and backroads /woods fun , he has a 15/51 . So the bike revs out about 65-70 mph. But now, that valve cover breather is spitting out oil constantly ,we noticed it cause it was spitting oil onto the rear tire . we made a catch can out of a water bottle and it had about 1/4 inch of oil in it after a few hours .

Now is this from it revving a lot higher now with the short gearing? Is it normal for the 426? He hasn't lost any oil on the dipstick . Does this bike need a catch can ?

Today was the first day we went out since winter , bike stayed in the gArage all winter, started up here and there .

  • GVDRZ400SM

Posted April 04, 2015 - 06:11 AM

#2

Bump anyone?

  • Rob28x

Posted April 04, 2015 - 04:39 PM

#3

Any signs of coolant in the oil? My WR426 kind of did the same thing and come to find out it was a bad head gasket causing coolant to mix with the oil. 



  • grayracer513

Posted April 04, 2015 - 06:15 PM

#4

Now my friend geared it down for stunting and backroads /woods fun , he has a 15/51 . So the bike revs out about 65-70 mph. But now, that valve cover breather is spitting out oil constantly ,we noticed it cause it was spitting oil onto the rear tire . we made a catch can out of a water bottle and it had about 1/4 inch of oil in it after a few hours .

 

Normal.  Stock gearing is 14/49 BTW, roughly what you have on it now.



  • GVDRZ400SM

Posted April 04, 2015 - 09:08 PM

#5

No coolant In the oil. Oil doesent burn and it's always fresh .

So that amount of blow by is normal ? I'm assuming it's caused from high revving ? Which is why I didn't see it with the taller gearing because it wasn't revving that high then.

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  • grayracer513

Posted April 05, 2015 - 06:43 AM

#6

At 70, the bike is running at just over 8000 with that gearing.  Then you said, "a few hours".  Yes, that's normal.



  • GVDRZ400SM

Posted April 05, 2015 - 07:26 AM

#7

I mean the bike tops out at around 70 but he wasn't doing 70 for a few hours . Ya know . Just like backroads riding and woods riding and in a few hours there was that amount of oil in the bottle .

  • grayracer513

Posted April 05, 2015 - 06:59 PM

#8

Could also be that it's getting tired, needs rings.



  • G-BRO

Posted April 05, 2015 - 08:40 PM

#9

My 426 always did this. Not a lot of oil, but a few drips, especially if the oil was over serviced.

  • Clutchup

Posted April 15, 2015 - 01:14 PM

#10

Hey guys this was my yz426 and i do think the motor might be tired. I was told that my bike everyonce in a while would puff a lottle smoke when clitchin up a wheelie. Now the other day i went riding all day rippin backroads with street bikes and was really revin her and today i drained my catch can and had alot of oil in it more then what it should i aldo checked my oil and was balery on the dip stick and i did run the bike let it sit for a min then check. After that day of riding i think my cam chain is streatched as well as the top of the motor is a little noisy. Im thinking go with a new piston and rings, cam chain, valve adjustment. Should be good for a while after that.





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