Yz450f hard to shift in every gear.


33 replies to this topic
  • hauser2169

Posted April 14, 2015 - 10:19 AM

#1

Hey all, recently got a 2007 yz450 for a steal. Has low
Motor time on a new top end including clutch fibers and springs. When the guy got it back from the shop, it was hard to shift I every single gear, hence why I got it so cheap. I rode it around and literally every single gear you have to use all your mite to grab another gear. From first to second I even hit neutral . I understand worst case scenario is tearing the cases apart and looking. For bent shift forks. Just wanted some input on this maybe someone here knows exactly where I should be looking. My rm 250 shifts like butter but this bike is a diff story . Hopping to get some help so I can put some seat time on this bike .

  • grayracer513

Posted April 14, 2015 - 01:24 PM

#2

"you have to use all your mite to grab another gear."

 

What is it specifically that requires effort?  Moving the shifter?  Pulling the clutch?

 

Does the shift lever re-center itself?

 

Does the clutch drag (fail to release completely when pulled)?  Hard to find neutral while standing?  Move the bike when you rev in gear with the lever held?



  • hauser2169

Posted April 14, 2015 - 03:08 PM

#3

when riding it, or sitting with the bike off, you have to use a great deal of effort moving the shifter., the shifter does re-center itself, and the clutch does not drag at all, the lever springs back just like it should and the clutch is grabbing. To be honest, i dont know if its hard to find neutral while standing, im currently at work so cant test that out yet. Basically the guy I bought it off of said that before he took it to the shop for the rebuild it would run through all gears with ease. when he got it back every gear was hard to shift, and the only thing that the shop did in the bottom end was a clutch. I dont know if i need to be ripping into the cases or pull the clutch basket off and check for something that is installed incorrectly or just worn. would just like some advice , new to fourstrokes , been on the 2 smokes a while. I apprectiate youre help and guidence



  • grayracer513

Posted April 14, 2015 - 03:50 PM

#4

Two-stroke or four, the gearbox is just the gearbox.  There are 3 things that come to mind that could cause this, but one of them is already ruled out.  If the shift shaft was binding because it was bent, then it should not re-center itself well if at all due to that same drag.  The next thing is extremely unlikely also, really, being "something" wrong with the centering spring.  Since there's only one, and there's no need to change it or disturb it when replacing a clutch, I doubt that's related.  Check these without disassembly by clicking down into 1st, then seeing what the lever effort is like when pushing down from centered.  If the shaft and spring are OK, the lever effort should feel normal.

 

Lastly, the cause might be anything that would cause the shift cam to be hard to rotate in the cases.  There again, if you're getting accurate information from the seller, this should not be the case, since there would not have been anything done to the shift cam.  But the cause could be as simple as the contact pin and spring under the neutral switch being out of place, something wedged under the "shift guide" (retainer plate for the cam), shift segment not squarely seated, stuff like that. 

 

The fork shafts in YZ450's up 'til the '14 are pinned to the forks, and they slide back and forth in the cases as they move.  However, if your shifting problem is consistent in all 5 gears, that's probably not where your trouble lies, either, since would all have to be equally faulty for that to be the case.  If you don't find anything outside, your best approach, IMO, would be to remove and inspect the neutral switch (the Philips screws are a PITA because they're loctited.  Use a hammer type impact driver tool to extract them) , and if nothing there, open the right side up and look for something tying up the shift cam.  You can remove the ratchet and pawl assembly and turn the cam with a 12mm deep socket for test purposes.   Then, if you still don't find the cause, you may be stuck with splitting the cases.



  • MJSANDS

Posted April 17, 2015 - 08:26 AM

#5

Check the torque on your clutch. They might have over torqued it in the shop.



  • grayracer513

Posted April 17, 2015 - 08:53 AM

#6

Check the torque on your clutch. They might have over torqued it in the shop.

 

That would not affect shifting.



  • hauser2169

Posted April 21, 2015 - 07:17 AM

#7

Do you have a picture of the neutral switch ? Manual is in the mail. Been waiting on that before really getting into the motor thanks for all your input

  • grayracer513

Posted April 21, 2015 - 06:06 PM

#8

Here you are.  Be careful with the removal.  It's plastic, and the O-ring may want to stick in place.

 

What might be wrong here is probably only if the shop had it out.  Look for signs that the contact pin or spring was out of position when it was assembled. 

 

 

Attached Thumbnails

  • NSwitch.png


  • 91kdx25088

Posted April 21, 2015 - 07:29 PM

#9

Why are you trying to change gears with the bike off and complaining when its not easy?



  • grayracer513

Posted April 22, 2015 - 07:05 AM

#10

Why are you trying to change gears with the bike off and complaining when its not easy?

 

You didn't read the first post very well.



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  • hauser2169

Posted April 28, 2015 - 07:29 AM

#11

Sorry been busy at work. Finally got the bike broke down . I took the sensor off, everything seemed fine. Took the clutch out and I can see the shift cam. If I pull up or down real hard on the lever I can see the shift cam go onto its detect to go up or down . But if I put normal shifting force it doesn't go into the full detent. I'm trying to get the cam out now but that lower 10 mm is a pita! And am j reading your last post correct? If it's shifting hard in all gears it's probably not the shift forks? That meaning the problem is somewhere on the right side of the case?

  • grayracer513

Posted April 28, 2015 - 08:09 AM

#12

Something binding the shift cam from rotating freely is what I'm talking about.  The cam itself cannot be removed without splitting the cases.  The "segment", which is what you are watching the detent lever work against, is removable, however, and once it's off, you can try rotating the shift cam manually with a 12mm deep socket.  It should turn "freely" except that you will need to rotate one or the other of the trans shafts so the gears can shift.

 

If it's OK until it tries to go full detent, maybe the "stopper lever" (index arm and roller) is not moving out far enough to allow it and causing the binding.



  • drtrcr400

Posted April 28, 2015 - 09:35 AM

#13

Something binding the shift cam from rotating freely is what I'm talking about.  The cam itself cannot be removed without splitting the cases.  The "segment", which is what you are watching the detent lever work against, is removable, however, and once it's off, you can try rotating the shift cam manually with a 12mm deep socket.  It should turn "freely" except that you will need to rotate one or the other of the trans shafts so the gears can shift.

 

If it's OK until it tries to go full detent, maybe the "stopper lever" (index arm and roller) is not moving out far enough to allow it and causing the binding.

To expand on this a little, I've seen people position the detent spring on the outside of the detent arm instead of in the hole in the middle. This would apply an excessive amount of preload to the detent and creating a condition similar to what the OP is describing. Normally one doesn't remove the spring and detent when splitting cases on these machines but the person who does could eaasily get the spring positioned incorrectly.



  • grayracer513

Posted April 28, 2015 - 09:46 AM

#14

 Normally one doesn't remove the spring and detent when splitting cases on these machines but the person who does could eaasily get the spring positioned incorrectly.

 

I always do.  One less thing in the way.  If all the shop did was a clutch, there was no reason for them to have it off, either, though.  Also never seen anyone flip the spring over, but who knows what some people might do.



  • drtrcr400

Posted April 28, 2015 - 10:06 AM

#15

I always do.  One less thing in the way.  If all the shop did was a clutch, there was no reason for them to have it off, either, though.  Also never seen anyone flip the spring over, but who knows what some people might do.

I tried to dig up the picture I had to better illustrate what I found but then realized the 2007 doesn't actually have the hole in the center of the arm for the spring to engage like the FI models. Not sure my thoughts apply here after all. Good luck.



  • hauser2169

Posted April 28, 2015 - 10:28 AM

#16

ImageUploadedByThumper Talk1430245704.708853.jpg
That's what mine looks like at the moment . And I removed the lower 10mm bolt fyi

  • hauser2169

Posted April 28, 2015 - 01:18 PM

#17

I just looked up the vin, it's a 2006 if that makes a difference

  • grayracer513

Posted April 28, 2015 - 01:58 PM

#18

It doesn't.  You'll have to get that right side crankcase cover off of there to check much farther, though.



  • hauser2169

Posted April 28, 2015 - 05:40 PM

#19

Which cover? Thought that was opened up as much as it could be with out splitting cases

  • grayracer513

Posted April 28, 2015 - 07:41 PM

#20

No.  The right side crankcase cover is still on there.  It's the one that houses the oil filter and water pump, goes up around the kick starter. 







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