426 Crank sprocket, good or bad.


14 replies to this topic
  • kubamtx

Posted September 08, 2007 - 10:56 AM

#1

Hi
Could you tell me how does worn crank sprocket look like?
I can hear preaty laud noise on the left lower engine side. So I decided to take of the cover and I found few metal shavings on crank position sensor (held by magnetic field). I'll make the photo of shavings.But I've changed oil and filter 6 times and I have never find any metal shavings or powder in oil filter. Oil is only darker no metal powder or anything. The lock washer lost its lips some time ago but I thought I found all of them in clutch hub but I can be wrong. So it is possible that those metal shawings are made of this washer. I own the bike form may 2007 and I've adjusted valve clearances. I havn't changed the cam chain because the head has been rebuild 2 years ago and the chain is tight (the chain tensioner is only 1/3 in his way out) so I tohought that the chain is ok.
The balance shaft has no play in or out and almost no rotating play so I think that the nut on the other side is tight.
I don't have flywheel puller yet so I coudn't take a photo of my crnak sprocket but I have seen it through holes in stator. I does not look like new but I don't have any comparison. So I need photo of new or worn sprocket.

  • grayracer513

Posted September 08, 2007 - 12:23 PM

#2

Is your 426 a 2000, or a newer one?

  • stroker yz426

Posted September 08, 2007 - 12:28 PM

#3

ok....the loud noise you hear could be multiple things......but as far as the timing gear on the crank....it should look like a new sprocket just like the one on your counter shaft.....when they are worn or bad....you see missing teeth....rounded teeth...if its worn...the teeth will be rounded back...like a beat up rear sprocket...the teeth will be really shiny and dulled...the should have a decent point on them to slip into the timing chain....i have a trashed crank on mine...and when i pulled the flywheel...my teeth all leaned backwards toward the rear of the bike...they were distorted....dull...with no points....and really shiny...while i was riding it i never had any loud noise from that side..i only heard the clutch giving up on me....i hope this helps...i will take a pic and try to get it posted this week end for you

later

  • grayracer513

Posted September 08, 2007 - 12:36 PM

#4

ok....the loud noise you hear could be multiple things......but as far as the timing gear on the crank....it should look like a new sprocket just like the one on your counter shaft.....when they are worn or bad....you see missing teeth....rounded teeth...if its worn...the teeth will be rounded back...like a beat up rear sprocket...the teeth will be really shiny and dulled...the should have a decent point on them to slip into the timing chain....i have a trashed crank on mine...and when i pulled the flywheel...my teeth all leaned backwards toward the rear of the bike...they were distorted....dull...with no points....and really shiny...while i was riding it i never had any loud noise from that side..i only heard the clutch giving up on me....i hope this helps...i will take a pic and try to get it posted this week end for you

later

The crank sprocket never looked like the front sprocket, and never had points. It is made for a Morse chain, and not for a roller chain, and therefore looks fundamentally different to begin with. But both the front and rear faces of the teeth should look close to the same in a healthy sprocket.

Again, what year is it?

  • kubamtx

Posted September 08, 2007 - 02:19 PM

#5

Mine teeth are straight both front and rear faces are very simmilar (maybe there is slight diference but only slight nothing serius). I can see only a little wear on bottom fornt side of the the theeth but this is not changing teeth shape yet.
So should I change the timing chain?
So I think I can say that my crank sprocket is ok.
I've got 2001 yzf 426 so there is no key problem.
I now that my clutch is making noise but I know why but I don't know why there is noise in lower left side.
And during riding with constant speed a can hear preaty laoud tapping noise,
but while reving or deaccelerating it disappears .The sounds I'm talking about
are loaud while idling or driving with constant speed.
I'm only affraid of this left bottom rattling noise.

  • kubamtx

Posted September 08, 2007 - 02:24 PM

#6

here are my shavings. This rounded one is the biggest and it's 3mm long.
Posted Image
I found them on crank position sensor (magnetic field works;-) )and no shavings in the oil filter..6 oil changes and nothing

  • 642MX

Posted September 08, 2007 - 06:50 PM

#7

here are my shavings. This rounded one is the biggest and it's 3mm long.
Posted Image
I found them on crank position sensor (magnetic field works;-) )and no shavings in the oil filter..6 oil changes and nothing


All I see is a red X....

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  • grayracer513

Posted September 08, 2007 - 08:06 PM

#8

I got to it. Unfortunately, that looks like fragments of a broken needle bearing cage. I suggest opening the engine up to see what you can find out about it.

  • kubamtx

Posted September 09, 2007 - 02:35 AM

#9

The rounded part looks like piece of something which is 6-7mm in diameter so not the needle bearing...I think.
But why it is not in oil filter and nothing is there from 5 months of riding. Those shavings could have been there even 1 year ago or even before head rebulit.
My oil and oil filter are always very clean. Bike goes strong and nothing but this noise is wrong.

  • 642MX

Posted September 09, 2007 - 07:45 AM

#10

The rounded part looks like piece of something which is 6-7mm in diameter so not the needle bearing...I think.
But why it is not in oil filter and nothing is there from 5 months of riding. Those shavings could have been there even 1 year ago or even before head rebulit.
My oil and oil filter are always very clean. Bike goes strong and nothing but this noise is wrong.


Take Grayracers advice and open it up and find whats wrong. It will cost a lot more to fix if it locks up.

  • kubamtx

Posted September 09, 2007 - 11:44 AM

#11

Yes I know tha Grayracer is always right and I know that is better to invest few hours of work then work and $1000 but it is strange for me that I found those shavings. The oil and oil filter are so clean. In my opinion those shavings where there long time ago or ..I don't know. I don't want to tear down the engine in the middle of seson. ;-( I was thinking about rebuliding the engine in winter ;-(

  • grayracer513

Posted September 09, 2007 - 12:25 PM

#12

You did say that there was a noise that concerned you. The noise could be normal, and you could be right. That all sounds reasonable.

But, if there's something wrong, the rebuild you plan on doing later on could become much more expensive if something blows apart in the meantime.

  • kubamtx

Posted September 09, 2007 - 12:53 PM

#13

I'll change the inner clutch hub (which has play between metal and alloy pars) and I'll change timing chain in this week and I'll check for noises then.
I'll consider rebuliding the bike now ;-(

  • kubamtx

Posted September 09, 2007 - 12:59 PM

#14

What do you think. What is the most possible way in the engine for those shavings to miss oil filter and stay on crank position sensor.

  • grayracer513

Posted September 09, 2007 - 05:39 PM

#15

I'll change the inner clutch hub (which has play between metal and alloy pars) and I'll change timing chain in this week and I'll check for noises then.

If the noise is gone at that point, you should be OK.





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