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


I took the exhaust off and checked all the apex seals. They all appear to be
springing in their slots. I also took out the Schrader valve from the tester
and checked the #2 rotor again, on the first attempt I saw a peak of about
60 PSI 10 more than last time but I can see the compression pulses get
weaker and weaker with almost every revolution.  Despite both being new now
I'm inclined to try a larger battery and or starter.  Replacing either or
even both would still be preferable to a complete engine tear down.

The battery I have hooked up advertises 300 starting amps. The starter is
re manufactured.  Is there a recommended minimum power for the starter and or
battery on a 20B?

Jay