YZ426 Debris in filter

8 replies to this topic
  • Deskjetser

Posted August 01, 2016 - 12:36 PM


I picked up a 00' 426 recently for a good price, starts 1st kick and rips like it should.


However changing the oil filter revealed a bunch of debris, imgur album below.



It seems to be a mix of steel and aluminum, but the black gunk and flakes escape me.  :(



Since its still kicking hard, I was planning on running it another 2 hours and seeing if there is a comparable amount of crap in the filter. But is that a sensible thing to do?


Any advice appreciated, since im new to this kind of thing.

  • William1

Posted August 01, 2016 - 12:39 PM


Black junk is probably clutch friction plates. Wipe it out and follow your plan to recheck in two hours.

Might not be a bad idea to take the clutch out and measure the parts. Some guys ride the clutch constantly and abuse them.

  • grayracer513

Posted August 01, 2016 - 03:51 PM


By the look of things, that oil filter has about 5 minutes of run time on it.  That amount of debris is far below what would normally be present after a normal oil change interval of say, 4-6 hours.


The black could be a number of things, but it's more likely than not the clutch debris Wm1 mentioned.  In addition to that, you'll find aluminum, usually from the clutch again, and fine steel from the collection of gears involved.  The engine shares its oil with the trans and clutch, and transmissions always shed metal into the oil. 


Cause for alarm is a sudden increase in the amount of any sort of junk you find, or the appearance of steel flakes, squarish in shape, and 1-2mm in size.  The flakes would mean a bearing race spalling off.

  • Deskjetser

Posted August 02, 2016 - 02:16 AM


I'll put another 2 hours like I planned on it then, and inspect the clutch as well as seeing if its the same story with the filter.


Thanks for the help, i'll get back and post the results soon as i'm done, but i'm waiting on parts so it could be a few days.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 450xThunder

Posted August 02, 2016 - 02:38 AM


On my crf the crankseal went sideways causing metal shavings

Attached Thumbnails

  • 1470134290673.jpg

  • grayracer513

Posted August 02, 2016 - 06:29 AM


That's one of the reasons that a YZF doesn't have a crank seal.  "Parts that are left out of a design cost nothing and cause no service problems." 


~Zora Arkus Duntov

  • 450xThunder

Posted August 03, 2016 - 07:38 AM


That's one of the reasons that a YZF doesn't have a crank seal. "Parts that are left out of a design cost nothing and cause no service problems."

~Zora Arkus Duntov

I did not know that about a yzf thanks

I'm a honda rider

  • ttreewalkerr

Posted August 03, 2016 - 02:30 PM


I had a slow accumulation on metal,, after a season it got loud clunk on decell. Crank main bearing ball delaminating, and inner raceway of that bearing began to pit from that ball.

  • Deskjetser

Posted August 13, 2016 - 01:49 PM


Sorry, going to be a few weeks before I can ask for an opinion on second filter inspection...




I done &%$#@!ed my thumb and knee up.  :banghead:  :foul:


Ill post 2nd inspection here asap.

Watch this space!

Related Content


Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Wilson the Blue Privateer by jetfuel

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.