09 YZ450f Shifting problem


2 replies to this topic
  • 660limited

Posted April 13, 2011 - 01:25 AM

#1

Hey guys, been lurking for a while but this is my first post here.

I built the bottom end of a buddys 09 yz450 as the crank siezed on him. He took the top end off and wasn't confident enough to do the bottom so I helped him out. I do build a few motors an do work on bikes an quads as a backyard/hobby mechanic for a few extra $$. So this wasn't anything new to me.

I put the crank an tranny in the cases, I spun the tranny shafts and shift drum all by hand and everything worked as good as it should. I get the whole bottom end together and give it back to him. He gets the top end on an clicks the shifter down. and it will not shift back for him. So he brings the whole bike to me last night. It was also never started yet.

We took the clutch off so we can get a clear view of the shifter mechanism. It will let you shift up or down 1 gear with no problem but thats all. If i take the ratchet mechanism out and the stopper lever off I can turn the shift drum by hand and go through the gears again like it should. But as soon as I put the stopper lever back on and try to shift it, I can go 1 or 2 up and then it seems like the lever binds up the mechanism. Im at a loss of things to try to do to get him up an running. I dont know if i should take the motor apart again and see if there is something not right on the inside, it just doesnt seem like I should if the gears spin freely and the shift drum moves properly without any pressure on them.

On thing I did notice is that when the shift segment is unbolted from them shift drum. I can move the drum in and out maybe 1/16" or less but there is some in an out movement on the drum. Is this normal?

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  • grayracer513

Posted April 13, 2011 - 10:40 AM

#2

The end float in the drum with the segment unbolted is normal. The segment clamps the drum to the right side bearing, which then controls the axial location.

As I recall, there is a small pin in the back of the segment to index its position on the drum. Check that you haven't made the mistake of bolting down the segment out of position and pushing that pin in flush.

Then try bolting the segment in place and shifting the trans with a 12mm deep socket, remembering the obvious; that you will have to turn the trans shafts a bit to get the gears to actually shift. If that works, keep assembling until you find the part that's tying things up.

  • 660limited

Posted April 14, 2011 - 04:47 PM

#3

well after lots of shifting by hand and spinning gears. I felt nothing wrong at all. So it all went back together. Got our fluids in and 3rd kick she fired. we had no out of the ordinary noises, and after a few minutes of warming up. It shifted into gear an away we went riding into the sunset. I dunno whether it needed the oil on the gears, or the motor to be started and get things settled into place or what. But she runs great an shifts like a dream.





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