My bus has been a bit of a pain to start after a while in the garage, but not any more! I am running twin weber DCNFs on a type 4 1800 and thought it was the fact I didn't have a cold start choke to play with. Much web searching later I discovered that the fuel drains back slowly away from the carbs and it was simply the mechanical fuel pump having to refill the carbs that was taking ages. I stuck a simple little one way valve in between the fuel pump and fuel pressure regulator and it has made a huge difference. The engine tries to catch or starts first turn rather than churning for ages. Definitely a step forwards!
