A trick I came up with years ago to,"Prime" a Brake Master Cylinder on Motorcycles if empty or the level has been allowed to drop too low.
Spit on the palm of your hand and place on top of the open MC and make a air-tight seal.Then pull the lever several times but keeping an eye on the fluid level and top up as you go.You should feel the skin on your hand being pulled gently into the MC as a partial vacuum is created.Then the fluid will flow out of the open bleed nipple.
Like Biblio I've never had trouble bleeding Motorcycle brakes unless the MC is faulty or there is a leak somewhere using just a jar with some brake fluid in it to act as a one-way valve with the tube from the Bleed-nipple.
I've never needed to buy or use any fancy stuff.
HTH
