01 YZ426F Clutch Plate Measurements?


11 replies to this topic
  • sirkuz

Posted March 15, 2008 - 10:35 AM

#1

Sorry for the n00b question but I am an new bike owner and had one almost given to me. It has a seriously bad slipping clutch so today I pulled it apart. I have all the plates sitting here on the kitchen table and was wondering if someone could quickly provide me with the measurements to see if I need to replace them. The basket is only slightly marked at all so I don't think that is the problem.

Be gentle guys, i like to learn by doing and this is my first clutch job :excuseme:

The guy before me said it also has a heavier flywheel in it for trail riding...would this greatly contribute to the slipping clutch? its hard to get the bike moving at all :confused: Motor will scream but bike doesn't want to go much.

Also what kind of oil is recommended here for the clutch?

Thanks!

  • Speedracer747-400

Posted March 15, 2008 - 11:31 AM

#2

The heavier flywheel will just make the bike harder to stall. It's not the reason your clutch is slipping excessively. I would recommend staying with Yamaha OEM fibers and steel disks when you replace the clutch pack. If you buy them online you can get them just as cheap as after market and they will provide more consistent clutch performance. I run Shell Rotella T 15W40 which you can get at Walmart for $9 a gallon. Just change it about every 10hrs. Shell actually did testing and it passed the JASO MA friction test.

Shell Rotella motorcycle forum
http://www.shellusse...page=1#Post3861

You can download the manual here and find all the measurements.
http://www.yamaha-mo...ice/manuals.jsp

  • sirkuz

Posted March 15, 2008 - 12:10 PM

#3

Thanks for the reply buddy. Now I just need to figure out where I add the clutch oil at. I called the dealer and got the recommended thickness and I am at 2.9 in the 2.9-3.1 in the friction plate range. The steels are perfect. No notching in the basket so I cant figure out why it was slipping so bad.

I am going to get a manual this week I think, change my fluids and see if there is other adjustments I can make to the clutch pack. It was so bad you could forget trying to start it up an incline at all LOL

  • 642MX

Posted March 15, 2008 - 12:25 PM

#4

Thanks for the reply buddy. Now I just need to figure out where I add the clutch oil at. I called the dealer and got the recommended thickness and I am at 2.9 in the 2.9-3.1 in the friction plate range. The steels are perfect. No notching in the basket so I cant figure out why it was slipping so bad.

I am going to get a manual this week I think, change my fluids and see if there is other adjustments I can make to the clutch pack. It was so bad you could forget trying to start it up an incline at all LOL


The engine oil is the clutch oil. Yamaha's use one oil for eveything. Make sure you change the clutch springs. The springs normally get weak and don't hold enough pressure on the pack causing it to slip. (maybe your original problem)

Replace the steel drive plates too. Just because they look good, doesn't mean they are not warped. A slipping clutch = heat. And excessive clutch heat will warp the steel plates almost every time.

You can down-load a manual at the top of the YZF forum page.

  • 642MX

Posted March 15, 2008 - 12:27 PM

#5

I run Shell Rotella T 15W40 which you can get at Walmart for $9 a gallon. Just change it about every 10hrs


As a Rotella user myself, 10 hours is too long for a change interval. Not wanting to start a debate, but at 10 hours its already out of grade.

  • Speedracer747-400

Posted March 15, 2008 - 12:31 PM

#6

Now I just need to figure out where I add the clutch oil at.


The engine and clutch share the same oil. Simply fill the oil in the dipstick hole at the top of the frame. Make sure when you do an oil change that you remove both the crankcase drain plug and frame drain plug plus the oil filter. You will need to fill in a total of 1.6L(1.69qt) when you change oil & filter. Check the oil level on the dipstick with the engine warm after shutdown. Unscrew the dipstick wipe it clean and then reinsert it without screwing it in to get the correct reading.

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  • Speedracer747-400

Posted March 15, 2008 - 12:35 PM

#7

As a Rotella user myself, 10 hours is too long for a change interval. Not wanting to start a debate, but at 10 hours its already out of grade.


Good to know. Did you have any samples tested by Blackstone Laboratories to determine a good change interval?

  • 642MX

Posted March 15, 2008 - 12:45 PM

#8

Good to know. Did you have any samples tested by Blackstone Laboratories to determine a good change interval?


I've never had a sample sent off. But after 5 hours, its obvious that its not 15W40 anymore. I change mine every ride, which is what I'd recommend. :confused:

  • Speedracer747-400

Posted March 15, 2008 - 01:08 PM

#9

sirkuz Did you happen to adjust all the slack out of your clutch cable? If you did this may be contributing to your excessive clutch slipping issue. Make sure you have 2-4mm of clutch lever free play. The gap is measured at the inboard leading edge of the clutch lever and perch.

  • sirkuz

Posted March 15, 2008 - 08:13 PM

#10

Wow thanks for all the info and suggestions guys. Very helpful. I have lots of stuff to try the next day I get to work on it :confused: I personally have not touched the clutch cable but will see what I can figure out to see if that is my problem. I will look at ordering some new springs this week. Anyone recommend an online vendor for the springs or should I just go to my local yamaha dealer for those?

  • Speedracer747-400

Posted March 15, 2008 - 08:32 PM

#11

If the fibers only measured the bear minimum I would replace those as well along with the springs. Make sure the steel discs aren't warped or a blue color due to being overheated. Honestly thought I think you would be better off buying everything this way you know what you have. The cheapest place I have found for Yamaha oem parts online is crotchrocket.com.

  • grayracer513

Posted March 15, 2008 - 09:00 PM

#12

If they're that old, and they've been that hot, I'd replace them anyway. They're probably baked hard as rocks. A new set is the best bet if the clutch is adjusted right and still slips.





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