Yz450f clutch help


5 replies to this topic
  • rockyf

Posted August 09, 2016 - 09:42 PM

#1

Hello
I am needing help with my 2012 Yamaha yz450f. I recently purchased the bike needing work. I replaced the cylinder and piston and timing chain. Fired up and runs awesome. I than go and test drive it and notice it just doesn't have the power a 450 should. I can't engage the bike into neutral while the bike is running. I removed clutch and noticed that basket has some fairy deep groves. The steel plates appear to be decent and not burnt same as friction. Could the clutch be hanging up and not allowing me to fully engage hence the power issue?

  • J_G

Posted August 09, 2016 - 10:23 PM

#2

First thing to check will be the clutch cable. If there is too much free play it might not be disengaging properly. 



  • Krannie McKranface

Posted August 10, 2016 - 05:13 AM

#3

 The 'not having the power' : meaning you think the clutch is slipping ?

 

The clutch plates would need to be meausured to determine if they are out of spec.

...it that is the actual power problem. 

 

 The ' not being able to find neutral' : with a hot or cold motor?

 

Pretty normal for anything but a brand new bike....and check the cable play at the perch with a hot motor. You must leave at least 1/8" gap at the perch.

Minor warping of the steels, notched basket, or worn out cable and bad adjustment can affect this.



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  • grayracer513

Posted August 10, 2016 - 08:56 AM

#4

Neutral from a standstill is tricky, alright, but it should be possible.  If it isn't, and the bike exhibits a tendency to surge forward when you rev it in gear with the clutch disengaged (lever pulled in), then clutch "drag", or incomplete release is the likely cause. 

 

Clutch slippage to the extent that you see it as a power loss is a separate problem.  To test for it, get out on a paved surface.  Roll up into at least third gear and note the RPM the engine is turning (by ear, unless you have access to an inductive tach).  Shift to 4th or 5th under power; the rpm should drop noticeably and sharply.  If it seems like it didn't drop, dropped gradually, or dropped only after you backed off the gas, the clutch slips.  Any rise and fall in RPM without an associated change in speed and no wheel spin is clutch slippage.

 

If you have both a dragging clutch and a slipping clutch, keep in mind that simple adjustment can only cause one or the other of these problems.

 

Clutch drag is caused by:

  • Improper cable adjustment
  • Warped plates (steels are the worst, usually)
  • Unevenly sagged springs
  • Notches in the basket and/or boss (hub)

Notched baskets can be filed, but they cannot be filed truly flat or square with the clutch plate tangs by hand, nor so that the tangs all contact all of the basket finger at the same time.  Furthermore, it increases the amount of clearance the plates have at the basket fingers, which causes them to strike the fingers with increased force as the power is dialed on and off.  It can be done, and often is, but it's a less than optimum fix that will work only for a while.

 

Slipping clutches are caused by:

  • Improper adjustment
  • Worn, warped or degraded clutch plates
  • Weak springs
  • Excessive wear or damage to the basket, boss, or pressure plate
  • Occasionally by oil with too many friction reducing additives

Yamaha sells complete clutch kits that include both sets of plates, new springs, and a cover gasket for significantly less than the total of these parts bought separately.



  • cpetz24

Posted August 12, 2016 - 10:05 AM

#5

 

Notched baskets can be filed, but they cannot be filed truly flat or square with the clutch plate tangs by hand, nor so that the tangs all contact all of the basket finger at the same time.  Furthermore, it increases the amount of clearance the plates have at the basket fingers, which causes them to strike the fingers with increased force as the power is dialed on and off.  It can be done, and often is, but it's a less than optimum fix that will work only for a while.

 

 

Gray,

 

What is your opinion on the clutch basket life after you were to machine away the notches in the basket?  Are the baskets hardened from the factory and does machining/filing them take that away? 

 

My dad is a machinist and I have access to a CNC mill.  We were able to make a fixture for the vice to hold the basket, and then machined the exact same amount off of every tang.  We just took more and more off in multiple passes until we got down to the point that there were no more grooves.  Sure, it increased the dimension between the tangs, but the basket almost looked factory when we were done and the grooves were perfectly machined radially outward from the center.  I should also mention I have a rekluse EXP in that basket.. Will that lessen the back and forth motion of the plates when the power is metered on and off?  My thinking is that the rekluse would keep the plates slightly engaged all the time keeping them from hammering back and forth on the tangs like a traditional clutch would.



  • grayracer513

Posted August 12, 2016 - 03:12 PM

#6

OEM baskets are not hard anodized.  How long it will last now depends on a number of things (which is why no one will warranty brakes or clutch plates, even in cars).  Usually about 40-60% as long as it took to get notched up in the first place.







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