Visualizing the clutch as an entire functioning unit is important. While each piece might not seem significant on its own, each is crucial to the functioning of the unit as a whole.
This list is certainly not meant to be exhaustive; rather, it is a starting place of potential issues you might run into. Every bike is different, but these were challenges we faced on ours.
The clutch, as it came to us, was incomplete; it was lacking a full set of driven and friction plates and had springs in very poor condition that needed replacing. Additionally, the duplex chain was overstretched and caused significant energy loss, not to mention wear inside the case. To anyone who might be working on these clutches in the future, be sure that the duplex chain is making contact with all of the teeth of both sprockets.
Our work was more complex than this, but it broadly fell into five large task areas. Each step was necessary to ensure that the clutch would function when we put it back on the bike. Our project lasted abut twelve weeks, although we worked on other systems as well.
Here you can see all of the clutch components disassembled; each has been cleaned thoroughly and replaced if necessary. Once the clutch was reassembled and placed back on the bike, it worked like a dream, aside from slippage due to issues with having tightened the clutch springs without lubrication. Once the bike was up and running, we were able to tune it to make sure it would not slip.
This diagram, pulled from the Tiger Cub Bible, shows how the oil system is configured on our 1958 Triumph Tiger Cub. The oil is constantly in motion, circulating from the top of the engine, down through the barrel, into the bottom end, and back up to the oil reservoir. The whole system is pressurized through a small oil pump that generates pressure through the rotation of the cam.
Most of the work that we did on the oil system involved ensuring that the passages were clear and that the oil could flow freely. Because some of the components, namely the oil lines feeding from the bottom end into the reservoir, were worn out, we had to fabricate new parts. The creation of new oil lines was simple, as it primarily involved bending copper tubing to match the previous specifications. Additionally, we worked to make sure the engine was leak free (or at least had as few leaks as possible- these bikes love to sweat!).