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My 2 cents
Hey Dan,
Scott/3Phase dissected the tranny and learned/postulated that the 2nd gear failure was more common with the early models that still had the kick starter gears. The later models without the kickstarter gears allows the 1st gear and such to wobble a bit more which often leads to the 1st gear going out First, but also often followed by the 2nd gear shortly thereafter...as what happened to my 81SH at around 50K miles.
I did the initial dremmel fix on both 1st/4th & 2nd/5th sets of gears in 2000 when I did my 1st rebuild. They held for some 25K miles, and not easy miles, little big bore kit, plenty of hard take offs, a few wheelies and such!
I decided to finally replace my BENT FRAME that I had gotten after my big wreck in '86, front end damage repaired by dealership, but they missed the bent frame neck, and I rode it for decades even after my initial rebuild in 2000.
So...did my 2nd rebuild 2016(16 years later) swapping frames and other custom work, but the bike/tranny had been working great. After 2nd rebuild, rode it to the XSSE and wouldn't you know it, the 1st gear started showing early signs of skipping again.
Would have been nice to have known that while I had it tore down to frame to do the dremmel again. 
This time, because of some other mods=solid Urethane engine mounts and such, I couldn't flip the bike over, had to use a large wooden frame and hoist/wrench straps and bike lift to pull the front up to an almost 90 degree vertical wheelie stance to be able to have easy enough access to the tranny pan. Thankfully I was already experienced in pulling the the shift forks, countershaft while the engine was previously on it's FULL BACK, so I was able to work on the tranny in this upright position, but it definitely wasn't as easy! Took me several attempts/30+ minutes to be able to get the countershaft back INTO the tranny, and this was WITHOUT doing the washer swap.
Yes, grinding does get into the softer layer of the gears past the hardened surface, but that's part of why the EXACTNESS of the grinding ISN'T as critical compared to factory fresh. The pressure/stress of the engine torque will eventually compress/wear the dogs and slots into a level of evenness since they are softer than the OEM hardened surface. The Dremmel fix has been done on lots of bikes, and I have only seen 1 posted about a DOG actually fracturing/breaking off, but the poster admitted to grinding too much off of the dog as well as leaving a sharp corner where the crack was able to get started and occur.
So....IMHO, if your 80 has 50K or more miles on it, I would go ahead and perform the Dremmel on both 1st/4th and 2nd/5th gear sets and have peace of mind not needing to worry about having to go back into it after finishing your build just to have the gears start skipping! YMMV.
T.C.
Hey Dan,
Scott/3Phase dissected the tranny and learned/postulated that the 2nd gear failure was more common with the early models that still had the kick starter gears. The later models without the kickstarter gears allows the 1st gear and such to wobble a bit more which often leads to the 1st gear going out First, but also often followed by the 2nd gear shortly thereafter...as what happened to my 81SH at around 50K miles.
I did the initial dremmel fix on both 1st/4th & 2nd/5th sets of gears in 2000 when I did my 1st rebuild. They held for some 25K miles, and not easy miles, little big bore kit, plenty of hard take offs, a few wheelies and such!
I decided to finally replace my BENT FRAME that I had gotten after my big wreck in '86, front end damage repaired by dealership, but they missed the bent frame neck, and I rode it for decades even after my initial rebuild in 2000.
So...did my 2nd rebuild 2016(16 years later) swapping frames and other custom work, but the bike/tranny had been working great. After 2nd rebuild, rode it to the XSSE and wouldn't you know it, the 1st gear started showing early signs of skipping again.
Would have been nice to have known that while I had it tore down to frame to do the dremmel again. This time, because of some other mods=solid Urethane engine mounts and such, I couldn't flip the bike over, had to use a large wooden frame and hoist/wrench straps and bike lift to pull the front up to an almost 90 degree vertical wheelie stance to be able to have easy enough access to the tranny pan. Thankfully I was already experienced in pulling the the shift forks, countershaft while the engine was previously on it's FULL BACK, so I was able to work on the tranny in this upright position, but it definitely wasn't as easy! Took me several attempts/30+ minutes to be able to get the countershaft back INTO the tranny, and this was WITHOUT doing the washer swap. Yes, grinding does get into the softer layer of the gears past the hardened surface, but that's part of why the EXACTNESS of the grinding ISN'T as critical compared to factory fresh. The pressure/stress of the engine torque will eventually compress/wear the dogs and slots into a level of evenness since they are softer than the OEM hardened surface. The Dremmel fix has been done on lots of bikes, and I have only seen 1 posted about a DOG actually fracturing/breaking off, but the poster admitted to grinding too much off of the dog as well as leaving a sharp corner where the crack was able to get started and occur.
So....IMHO, if your 80 has 50K or more miles on it, I would go ahead and perform the Dremmel on both 1st/4th and 2nd/5th gear sets and have peace of mind not needing to worry about having to go back into it after finishing your build just to have the gears start skipping! YMMV.
T.C.
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