The Actron CP7828 is the compression tester I have in my toolbox. It comes with everything you need, including multiple adapters for all types of motorcycles (10mm, 12mm, 14mm, 14mm long reach, and 18mm standard spark plug thread). Also, it comes with extra o-rings and valves in case they are damaged during use. I initially bought the Actron CP7827 shown below on the right, except it did not come with the 10 & 12mm adapters. Spend the extra few bucks and purchase the one shown on the left.
Here is a short video explaining why I chose this model over others that are available in the same price range.