Certainly a leak down will tell you something on a 2 stroke DD but it cannot isolate isolate well as it can on a 4 stroke. I am a big fan of leak-down testing on 4 stroke motors, in fact I consider it the "other half" of the evaluation that starts with a compression check. IOW, a compression check foliowed by a leak down is an extremely valuable; a compression check by itself can be misleading.
My issue with it in this application is that it doesn't seem worth the trouble due to the difficulty in isolating. Basically, as described, the test results sort of mimics a compression test. In fact, that may be the point since it's easier to perform than a compression test - no need to run the engine for each test.
One thing seems very odd re the test shown in the link. Unless I missed it, there is no mention of piston position for the test. You can't do an accurate leak down without the piston at TDC, or at least with each piston under test in the exact same position - TDC would be the easiest to find. In fact, if you did this test with no regard for piston position - as the guide seems to indicate - you could end up with total, immediate leak down if the piston is below the intake port.
Frankly, it appears to me that the test as described could ONLY work with a 4-stroke motor...
In any case, if you feel a leak down is a useful test procedure for a 2 stroke dd, by all means use it. It certainly can provide "additional information."
