How to defeat this lock?

I have the seat lock from an '81 KZ1000, however there is no key. If I can get it apart, I can resequence the pins to match my key though (based on the helmet lock from the same bike, in which I was able to rearrange three of the four pins to get a match). Unfortunately I am stumped by mystery of disassembly...

So this lock appears to have a one-piece cast housing with nothing visible to the outside except the mechanism that locks down the seat. Closer inspection revealed a shiny pin in the barrel about 3/4" from the end, which seemed a likely suspect for holding the lock in place. I used the dremel and a #54 drill bit to remove the pin until the drill dropped slightly, but no luck getting the lock to rotate or pull out. So I put a little more pressure on the drill and it dropped down another noticeable amount (probably into the key slot). The #54 bit is large enough to remove all traces of the pin, but I still can't get the lock portion to budge. I tried twisting it with a screwdriver, and using a key to try and pull it out. I also removed the shiny face of the lock but found no clues behind it.

The only other suspect I see is the center pin for the locking latch, which is peened over on one side. Below that is a large spring-loaded pin that seems to activate the latch. And there is a small hole below that pin which is drilled through the bottom of the lock. Perhaps there is something hidden underneath all of this that actually holds the lock in place? I just can't tell...

So I'm wondering if anyone has ever actually disassembled one of these locks? Anyone have a clue what I need to do to get this apart?

FWIW, I finally got it to pop open. It turns out that pin I drilled out IS the key to getting the lock barrel out. There must have been a sliver of the pin left in the hole, but after using a dental pick to feel around in the hole I tried pulling out the barrel again and it finally moved out enough to grab it with some pliers. I hosed it all down with brake cleaner to remove the gunk so I can see what I'm doing, now trying to figure out how to remove each pin of the lock. The barrel looks almost identical to the one from the helmet lock, except in this case the spring-loaded pins are not just popping out once it was clear of the housing. Something is keeping them locked in the barrel, I'm still searching for a pin or other mechanism that is holding them. At least I'm making progress...

Of interest... the helmet lock only had pins in four of the six slots. The seat lock has pins in all six positions, and they appear to be of the same style in both locks. It wouldn't surprise me if all four locks used the same kind of pins, which gives me extra parts to play with. I doubt I'll be able to match all six pins to the existing key, but maybe I can find someone who has a supply of these pins that I can use to finish the job. For now I'll be happy if I can match 3-4 pins and get the seat latched down.

So the pins (wafers) on this lock have little nubs on the sides which create a friction-fit into the barrel. I used a small flat screwdriver to push them out of the barrel, then cleaned each with a brass brush (they had a lot of corrosion and gunk on them). I managed to meet my goal, I was able to get four of the wafers to match my key, leaving me with a mostly functional lock. Tomorrow I'll get a new pin driven in and then I can mount the lock back on the bike. Woot!

Nice work! A buddy at work has to re key locks, he has the cheater tools but sometimes they blow up at the last second lol

Thanks! I've been practicing lock-picking for a number of years, and unfortunately these locks are quite easy to pop open, but as with any lock these are only meant to to discourage 99% of the population. The mechanics inside them are fairly simple, you have different wafers that match each slot on the key, and when all of the wafers are lined up correctly then the lock will open. If I had any knowledge of who made these locks then I could probably find a set of replacement wafers on ebay and match all six key slots for both locks, but I figure anyone who can get past these locks won't be deterred regardless of if I'm using one wafer or six. I think the ignition lock is probably the most important on the bike though, and that one is the original that matches my key so it is fully functional.

Got the helmet lock reassembled, and the seat lock is all done except for finding something to replace this pin. Wonder if I should just replace it with a screw so I can take it apart again later if needed?