even if they used the incorrect tool (compression tester) the readins would be consistently low across all 4 cylinders. Mechanics are not silly by the way: they know when a compression guage adaptor does not fit the bike properly as the leakage is genrally obvious.
If I were you I would have them perform a leakdown test as this will help to pinpoint the problem and help you to decide what course of action to take.
Bookmarks