tommarrow in my shop class we are doing compression checks on our vehicles, and of cource i am the only one with a rotory, and my instructor at least knows about them but nothing specfic. the shop is the best for a college on the west coast, but does not have the mazda specific rotary tools so i get to use the "standard" tools.

with that being said any specific instructions on compression testing with the rotray that are different from the standard preocdure for piston engines. obvously i know i am looking for 3 bounces per rotation. from searching i am gettng the impression that i use the top plug ( leading) . i didn;t see any specific instructions when cheking the archives

but anyhting else? woudl really like to be able to drive back out tof the bay when am done

 

The leading plug is the bottom one not the top.

 

The leading plug is at the bottom, like Wan said. It should have a L next to the spark plug hole on the rotor housing, and a T for "Trailing" by the trailing plug. Anyway, you are right, you are looking for three bounces, and you want them all to be pretty close to the same amount of pressure. Some people recommend using a handheld video recorder to record the tester, then play it back in slow-mo to get a better look at it. Also, there will be a relief valve on the gauge. You want this all the way open (or off if it comes off). This lets the needle bounce. If the gauge is closed, and your first compression is 120psi, the needle will go to 120psi. If the next one is 30psi, that ain't enough pressure to over come the 120psi so the gauge will not move and you will never know you have low compression on that side of the rotor.

If I explained that wrong about the gauge, someone jump in and correct me. (None the less, the valve does have to be open, even if thats the wrong reason why.)

You could also just do a friends car for the class, but I'd take this oppertunity to show of a rotary engine.