slowriding, on 20 March 2012 - 10:28 AM, said:
not specifically referring to your bike but usually when a bike pops out of a gear continuously it is from the dogs on the gears, or dogs and slots, getting damaged edges and then it creates a sideways force that pushes the gears apart and against the shift mechanism. As for 2nd gear being the one I would suggest it gets hammered the most on acceleration and quick shifts. Often for strength the 1st and 2nd gears are on opposite sides of the gearbox against the case and this means both slides are in motion for the shift. In a worst case scenario one bad shift could do the damage but not likely. Some of the higher performance bikes are starting to use undercut gears which will suck themselves together under load rather than 90degree faces.
Could also be a bent shift fork. Could also be a shift lever hitting the case on an upshift either because it is bent or adjusted to high.
Does the problem occur on downshifts? Because of neutral affecting the shape of the cam that holds the shift drum in each gear you really have to get 2nd into gear on upshifts, the spring and roller won't finish the shift for you like on other gears, or at least not as soon in the rotation.
Doesn't occur on downshifts. I highly suspect it's the damaged edges of the gears, but I'm just surprised it came on so abruptly.
For the short term I'm going to adjust my shift lever down a bit because upshifting to 2nd has been a real pain.