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Discussion Starter #1
it looks like the problem isn't that the 5th gears weren't heat treated properly, the problem occurred when second gear was pressed up to 5th gear. it's very critical that 2nd gear is pressed to specific location on the shaft, if it's not perfect 5th gear wont spin correctly. i believe when they pressed 2nd gear at the factory it jumped past where it was supposed to be set and as a result 5th gear gets damaged, this must have happened a lot because there's a lot posts about 650s with noise in 5th gear only, i guess they didn't want to take the time to reverse press it and repress it correctly. there only .2mm margin of error when pressing 2nd gear
 

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Discussion Starter #2 (Edited)
8 hrs in and got the cases split and both transmission shafts removed, what i thought happened is now confirmed. during the factory pressing operation 2nd gear gear jumped and went to far onto the shaft which is why the main 5th gear doesn't mate correctly to the counter shaft 5th gear, the overall gear set length is supposed to be 103 mm to 103.2 mm for the main shaft. on my main shaft it was reading 102.5 mm for the gear set length because second second gear slid to far when they pressed it , i bought two brand new 5th gears counter and main, i'll be doing the pressing operation tomorrow if all go's well i should be riding sometime on friday, i have to get a good camera that shows fine details what resolution should i get for a reasonable price, so i can post some good pics on this forum. wait till i show you the damage on the gears you won't believe how bad they got
 

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For the Dummie, What do you mean when you say "Pressing"? Is it putting the gear on the shaft? Did the factory put it too far or not far enough?

My dad used to work in a tractor factory and they would freeze a drive shaft and then put a heated gear on the shaft and then let the combination reach a common temperature. It was very permanent bond. Just curious. Thanks Augie
 

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Discussion Starter #4
For the Dummie, What do you mean when you say "Pressing"? Is it putting the gear on the shaft? Did the factory put it too far or not far enough?

My dad used to work in a tractor factory and they would freeze a drive shaft and then put a heated gear on the shaft and then let the combination reach a common temperature. It was very permanent bond. Just curious. Thanks Augie
the factory pressed it to far, either because it jumped ( sometimes when pressing something it doesn't slide smoothly down the shaft it will jump in small increments ) or when they measured the overall gear set length, they measured at the hub of second gear which is thicker than the gear face. either way it went to far onto the shaft. the quote from manual states " when pressing 2nd gear if it go's too far you will need to press it back and retry until the gear set length is 103 mm to 103.2 mm if there is insufficient clearance between 2nd and fifth gear 5th gear will not rotate correctly " end quote
 

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Discussion Starter #6
1999 Yamaha XVS650 XVS 650 V Star Transmission Gears for Parts Only | eBay here's one that looks like mine. the factory not only pressed second gear too far they also installed it backwards. the notches on the top of teeth on second gear are supposed to be out away from 5th gear, you can see in the picture the notches are towards 5th gear, i can't believe the yamaha tecs could this and do it often too
 
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