2009 YZ450f Stiff Shifting


5 replies to this topic
  • Zabrow187

Posted July 05, 2015 - 02:20 PM

#1

I have put something up before about the clutch in my YZ450f not disengaging enough, and causing what feels like drag.  I have since replaced the basket, both sets of plates, springs and the push rod.  While the symptoms are better, the bike still has what I would describe as a clunky clutch.  When not wearing boots, I feel like I have to work too hard to get the bike to shift.

 

I am starting to suspect it maybe something more internal like shift forks but I REALLY REALLY REALLY don't want to split my cases to check my shift forks.  Is there a test I can do, with my bike in one piece, to definitively tell me if my shift forks are bent?

 

Also, I had an idea to install a larger ball in my clutch to see if that provides me enough lift to make my clutch disengage.  Has anyone done that before?  What ball do you use. The stock size is 11/32 (part # 93511-32027-00)

 

 

The parts installed were a GYTR basket, Tusk clutch plates and springs, OEM Yamaha push rod.



  • grayracer513

Posted July 06, 2015 - 06:18 AM

#2

I think I see the problem with your clutch:
 

[...] Tusk clutch plates and springs, ...

Use OEM.

 

If your bike stays in gear under full throttle, your forks aren't bent.  The effort you feel is coming from some other part of the linkage.  Does the lever re-center itself normally after each up or down shift?



  • Zabrow187

Posted July 06, 2015 - 06:48 AM

#3

I think I see the problem with your clutch:

Use OEM.

If your bike stays in gear under full throttle, your forks aren't bent. The effort you feel is coming from some other part of the linkage. Does the lever re-center itself normally after each up or down shift?


Yes it does. The level returns to zero after each shift.

I understand your reservation about Tusk clutch systems, but Myself and my father have run Tusk clutch kits on several bikes, including race bikes without issue. I don't think the plates and springs are the problem.

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  • grayracer513

Posted July 06, 2015 - 08:20 AM

#4

The Tusk plates aren't affecting your shifting, but they are problematic, however fond of them you may be, and they won't ever work as well as Yamaha plates.  The lack of a clean release is just one of their "endearing features".

 

Shift effort at the lever should be evaluated at low speeds, in motion, without a load on the transmission, neither accelerating nor decelerating.  This will tell you if any part of the mechanism the moves the forks is binding.  If it shifts well here, but the shift effort rises as you speed up, it may be that you have a bad trans shaft bearing causing the problem.  You can check for this by removing the clutch plates and the rear chain and seeing if each shaft rotates smoothly without inappropriate drag (there will be "some" due to oil seals, etc., but it should be very little). 

 

Other possibilities include anything that would cause the shift cam to be hard to rotate, or something that would make the shift fork shafts bind in the crankcases as they move back and forth.



  • grayracer513

Posted July 06, 2015 - 08:24 AM

#5

Incidentally,  the idea of using a larger ball will do nothing at all, even if it fits into the hole in the shaft, because you will need to readjust the free play to the same setting you now have, and the pressure plate will lift the same amount. The lift is entirely determined by the upper and lower levers and the available lever travel at the handlebar.



  • soulsedg3

Posted July 10, 2015 - 07:21 AM

#6

Yes it does. The level returns to zero after each shift.

I understand your reservation about Tusk clutch systems, but Myself and my father have run Tusk clutch kits on several bikes, including race bikes without issue. I don't think the plates and springs are the problem.

 

i'd definitely go off what gray is saying....everything i've asked about my bike, that he's suggested, has been dead on.    He know's his yamaha's well. 

 

Somethings are more fussy in different manufacturer's.     Tusk plates may work well in some,  but not so much in other, due to the basic design of the machine. etc.   

 

I know i've had 2 strokes in the past that didn't like aftermarket clutch plates.   once i went OEM,  the bike was night and day in clutch department, and i wasn't burning em out as often.







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