The injector pump was leaking oil. I ordered a seal kit from HVCcycle. After installing the kit, I discovered seals were not the primary cause of the leak. The pump shaft had rusted and was pitted enough to let oil seal by the seal.
Turns out the TY175 and RT180 share the same oil pump. Pumps for the RT180 are common and cheap. A “eBay” pump cost less than the rebuild kit and stopped the leak. The newer injector pumps lack the manual pumping wheel, so that cannot be primed by hand. I made a quart of pre-mix and started the bike with it before switching over to straight gas.