Problem with VW engine is that you have to completely tear down the engine, split the cases to access the cam. You might be able to pull the oil pump and see if there are any markings visible through the hole on the end of the cam. I'd recommend taking time to read over the VW trike threads especially Snu's Tech, tech, tech thread. There are several books and small specialty tools that you will need to work on the engine that are mentioned in these post. Post pictures as you disassemble and somebody should be able to help.