Motorcycle Repair: Something seems like slipping in 2nd gear, detent pins, clutch discs

Question
I have a 1972 Honda CL450K5 that I have completely restored. This problem presented itself from the very beginning after restoration.
It seems like the clutch slips in second gear ONLY!. I put new OEM fiber clutch discs in and bead blasted the metal discs. I put a second washer under the regular washer on the clutch springs. These washers were drilled out to .484" so they would clear the center post the springs slide over. I have bypassed the kill switch and put a brand new set of points and plate, thinking it might be an electrical problem.
The engine runs perfectly with no hiccups, burps or farts. Accelerating in all of the other gears is smooth and powerful. but second gear will slip and jerk as you drive. No metal banging noises, it just accelerates up and jerks when it catches. Very uneven.
When up on the main stand in second gear it gets jerky, but pull in the clutch lever, the wheel and chain rotate smooth as butter. I can't imagine a transmission gear slipping in and out. There's no pressure to place it back in if it did slip out.  If it was the gear on the clutch basket, it would do it in other gears as well.
I am at my wits end, can you help?
Thank you, Paul

Answer
Hi Paul,

This problem is commonly a loose shift drum detent wheel
and wear on the detent pins on the end of the shift drum.

https://lh6.googleusercontent.com/-cEkTssKz2oM/T6rwfV0WxnI/AAAAAAAAByM/JYoi_yoH290/s800/IMG_1798.JPG

If those don't fix it then the shift drum and fork guide pins
could be worn.

When the detent wheel is loose the shift drum can jump
back and forth. The detent wheel holds the shift drum
in position so if it is weak the drum can rotate.

This seems to be mostly a second gear problem.

Worse case would be worn gear dogs or gears improperly
spaced and not engaging far enough.

I would start by checking the play on the shift detent wheel
and the pins that it rides on for wear.
These need to be in good shape so it holds the drum
solid when in second gear.

Most other problems would require pulling the transmission
apart so hopefully the detent wheel is the problem.

Check any return springs involved too.

Wayne S
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