I've been reading about doing a leak down test on the cylinders. I've never done one. Figured it must be a piece of test kit equipment that I need in my shop. So while at the auto parts store I asked if they had one. They had no idea of what I was talking about. So what's the deal or where do I find one?

 

Good auto part store.... or ebay. Good old simple compression test is good enough for a street bike. Just takes a little more work to use it. On a car it takes two people. Be sure to open throttle wide open.

 

I bought mine at Princess Auto, so you should be able to find one at Harbor Freight. It is similar to a compression tester but a little more complex. You need an air compressor to run with it.

Here's a bunch on eBay ...
http://www.ebay.com/bhp/leak-down-tester

You can make your own, but at less than $50 i bought one ...


It is a useful tool to have before starting to tear down the top end. It gives a good indication whether there is a problem with the rings or the intake or exhaust valves.

When using it you should completely remove the pushrods to ensure that the valves are closed and stay closed throughout the test. You will be using your compressor to pressurize the cylinder thru the spark plug hole, and it is likely to move the piston down, open the valves slightly, and invalidate the test.

During the test you listen for air escaping thru the intake, thru each exhaust, and thru the timing plug hole. There should be none past the valves, and a small amount past the rings thru the timing plug hole.