Getting your engine to talk to you part 4... Top end

Getting your engine to talk to you part 4
Time for your top end to share its secrets.
The one test tool for top-ends that I use more than any other is a cylinder leak down tester.
This tool can troubleshoot and trend monitors the health of your engine.
The typical leak down tester pressurizes your 4 stroke top-end to 80psi. The tester is made up with 2 gauges that are connected by a calibrated orifice one reads incoming regulated air pressure of 80psi and the other reads what is in your cylinder at top dead center of the compression stroke.
The tester simply screws it into your spark plug hole and you use a socket and breaker bar to keep the piston at Top dead center.

In Troubleshooting mode.
1. With the cylinder pressurized to 80psi and held at Top dead center on the compression stroke. you use your ears, eyes and soapy water to chase down a leak.
2. place your ear next to your air filter, hear air escaping? that's a leaking inlet valve.
3. place you ear next to your exhaust, hear air? that's a leaking exhaust valve.
4. with a cold engine remove the radiator cap, see bubbles coming up? that's a bad head gasket. (it also could be a cracked head).
5. place your ear next to your engines breather tube, hear air? that's escaping past your rings.
6. now spritz some soapy water around your head and cylinder bolts looking for bubbles that would show a leak.

In Trend monitor mode
1, The second gauge will be reading your internal cylinder pressure. To trend monitor, the health of your engine simply record the difference in pressure. When the rings are bypassing (4psi on MX bikes) and (8 psi on trail bikes) its time for a fresh top end. You can watch a fresh top end, slowly wear down over time if you are using this as a trend monitor 

Note 1. This job is way easier with a helper to keep the piston at top dead center with a breaker bar.

Note 2. There are several models out there but my favorite are the ones that have 2 identical gauges.

Note 3. if you hear air escaping from the exhaust valve be sure that the decompression mechanism is not holding the valve open.

Note 4 This youtube video will give you a good overview of how to use this tool.
https://www.youtube.com/watch?v=a3yLKOdRdPo