09 yz450f trouble shifting

Have an 09 yz450f, with about 35, 40hrs on it. Have changed oil regularly approx every 5hrs. Last two times I have been out riding mx I could not shift from 3rd to 4th, this only happened once each time out felt like the shifter could not go up anymore, had to downshift then go back up. I usually use the clutch to upshift occasionally I will just let off the gas and upshift. Any ideas im thinking it could be a tweaked shift fork.

Do you feel any binding when you move the shifter?

Also change the oil more often. Every 1 to 2 hours. I use Mobil One.

No binding just feels like its all the way up like its in 5th wont go any higher ill try changing the oil more

A 4-5 hour oil change interval when using Mobil 1 motorcycle oils (Racing 4T or V-Twin) is OK.  If using an automotive oil, 2-3 is safer.


What sometimes happens is that something interferes with the shifter re-centering.  When that happens, it fails to latch onto the next ratchet point on the shift cam, and fails to advance it.  In that situation, the lever would move through what seems like its normal travel without doing anything, instead of just not moving. 


Also, note that the locking lugs on the gears are undercut slightly so that the gears tend to hold in gear under a load of their own accord.  With a new-ish gearbox, it can be very resistant to being shifted under power because of that, and the best cure is to learn to roll the throttle back briefly while the shift is made.

Thanks gray was hoping you would reply to my post, ill work on my throttle control while shifting

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