I've had my 20B on a test stand all wired up and ready to run for
    months.  But even after endless troubleshooting I haven't been
able to    achieve a successful start.

    Today I hooked up a compression tester and I?ve probably found
the    problem.  Rotors one peaks out at 35 ? 40 psi and leaks down
the instant    I stop cranking the engine, rotor two peaks around 50
psi and leaks    slowly down, rotor three peaks and will hold about
60 psi.  I didn?t own    a compression tester when I did the rebuild
and figured since I replaced    practically everything but the
rotors and housings I should be OK.

    Any thoughts, comments, or suggestions before I start tearing
down the    engine?

    TIA

    Jay

    Remove the schrader valve from the compression tester and watch
it    while the starter turns the engine over. It should equal pulse
70 to 80    psi three times in a row on each rotor.

    Sounds like you have one or more stuck
    apex seals. Remove the exhaust manifold and use a small screw driver
    to push on the apex seals through the exhaust port. If you cannot
    feel them move in and out under the influence of the springs you
    have a stuck seal. Spray WD40 in there and keep trying.
    Remove the plugs and put some auto transmission oil in the
engine.    Turn it over a few times and let it sit over night. Then
check the    seals again. Once you get it running it will clean
itself up.

    Are you mixing oil with the fuel?

    Paul Lamar

   I have heard a few comments over the years of leftover carbon in the
   apex slots sticking seals after a rebuild.
   Do you recall any issues getting the apex seal springs inserted,
 that is   a hint.   As Paul says, pull the exhaust, check the apex
springs for spring.  Try   ATF in the plugs/exhaust, turn over the engine
   and work the apex seals manually.

   How bad was the edge flaking on the rotor housings you used?
   vendor seals?

   Cheers
   Cary

I also meant to ask about the battery and starter.
A low battery/poor starter will result in low compression even if
everything else is in order.
Sound or video of a start attempt could tell us a lot.
~Cary

That is so true about the starter. Randy Lewis just went through
that exercise. You must really spin that engine.

Paul Lamar

It's been some time since the rebuild so I don't remember with any certainty
details of installing the apex seals. They are OEM parts and I don't
recall any slot flaking.  The starter is a brand new as well as the battery.
If Paul's suggestion doesn't get me going I'll record the engine
being turned over.

Jay


Years ago I had a R100 with a worn out 10A engine. It had 40# compression. Did
the schrader valve removal. The engine cranked over well. To start it, I put a
bit of oil down the carb to help seal the apex seals. If it got below 1500 RPM
it would stall. Still went fairly well once the revs up. It would blow the
rubber oil fill plug out if I gave it full throttle due to blow by. I finally
got a RX2 engine to put in from a recycler. The 10A parts were already a bit
tough to get in the mid to late '70's. Mazda Canada will not sell rotary
overhaul parts, just reman engines.

Dale Davies