142F clutch issues.

[Zcw1]

Good evening ! I have a 142F 49cc kit, and it runs flawlessly. However I wore the belt out and decided to upgrade transmissions. I purchased the “ 5G Dual chain transmission” as well as a new clutch. However after installing the clutch will not engage when the transmission is mated to it. However I bolted the clutch to the engine and started it without the transmission attached and the clutch expands and contracts as it should. I then tore it back down and put a small washer between the bolt and clutch and assembled it, however the washer keeps the clutch engaged. I am at a loss and I am out of ideas. Do I need some sort of key shaft? Pictures below.