Knock in Transmission

2008 YZ450F

 

I recently had to replace some gears and one shaft in the transmission and I have rode it about three times since with out any problems but I went to load it in the truck today and there is a light knock in the transmission while rolling the bike in nuetral. I put it on a stand and took off the chain and I can rotate the sproket by hand and it turns smoothly but at the same spot everytime it has a slight knock. It has the same sound like if you rotated the sproket back and forth and you can hear the teeth between the gears mating. 

 

Any ideas ???

I may be just a little over cautious but I didn't like it when the transmission locked up before.

You say the knock happens in the same spot.  What is the reference point?  Once every rotation of the front sprocket?  The wheel?  What?

You say the knock happens in the same spot.  What is the reference point?  Once every rotation of the front sprocket?  The wheel?  What?

I tried a few more things and I hope I can explain this.

 

With the chain off I rotate the front sproket CCW and the knock happens at a different but consistant spot every time. The spot of the knock moves CW about two teeth for every rotation of the sproket.

 

I also cranked the bike on a stand and with the chain on, I put the bike in gear trying every gear. The bike will jerk occasionally like it is jumping gears. 

I also cranked the bike on a stand and with the chain on, I put the bike in gear trying every gear. The bike will jerk occasionally like it is jumping gears. 

 

The part above is normal.  What happens is that the wheel lashes back and forth with the chain slack, and if the bike fires with a load of slack, you get a jerk.

 

The knock sounds like a damaged tooth on one of the main shaft gears, likely 4th or 5th.

The part above is normal.  What happens is that the wheel lashes back and forth with the chain slack, and if the bike fires with a load of slack, you get a jerk.

 

The knock sounds like a damaged tooth on one of the main shaft gears, likely 4th or 5th.

Thanks Gray,

I did pull the clutch basket off and looked thru the opening to see if I could see anything but it looks like I'm splitting the cases again.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now