Grinding at 2nd gear

[vint1100s]

Help out there?
I'm trying to button up my 1978 XS but it won't go into 2nd gear while running. First is no problem but it just grinds when trying to shift to 2nd on the center stand. I understand XSs have issues with 2nd gear but while on the bench just turning the drive wheel by hand all gears work. I have the bike upside down now and found a 1/8 x 5/8 or so pin in the transmission pan. The shifting fork appears to work properly turning the shifting cam(drum) and all pins appear accounted for.
so I am curious what is happening when the bike is running that makes it not want to shift to 2nd.
Help

[CatatonicBug]

Welcome! You've discovered the classic 2nd gear issue. The gears mesh from the sides (dogs and slots) and those parts are what wear out and round over. At slow speeds, they are fine, but under any torque, they force themselves apart. Do some reading, especially in the tech tips section, and learn about the 2nd gear fix. I've done it myself on several bikes, and I can now do it start-to-finish in about 4-6 hours. Some folks take it in longer stages and take 2 days to complete it.

Good luck!

[jetmechmarty]

Some folks take it in longer stages and take 2 days to complete it.

I did mine in about 3 months!

[CatatonicBug]

I did mine in about 3 months!

Well, there are those of us who CAN'T wait that long. If I take my bike apart on Saturday, I need it to be back together to get to work on Monday!

[DGXSER]

That pin in the tranny pan did not just fall out of the sky, something came loose somewhere. Are you sure you have all the pins in the shift drum? Have you pulled the gears out before? Does the shift fork shaft spin around?

As to slipping out of second under torque, well, for it to do it on the centerstand those gears would need to be pretty dang torn up!! Typically, the bike will roll out fine in second gear unless you give it some good throttle even with worn gears, so if that is your issue, they must look like holy hadies in there.

[brcree]

2nd gear wohs....

Just did my 2nd gear dremel fix a few months ago........I had 3 broken gear teeth in my pan.....Look past the secondary gears to the primes and turn the back wheel to see all the teeth. Runs smooth as silk now! Just can't get it titled here in S.C. Good luck man!