Paul

     Long time ago there was discussion here of comp. testing. I ask
   because my eng is very difficult to start and Race Beat insisted a
comp.
   test was in order. A compression gauge with a check valve read
120psi on
   the rear and 85 on the front.  I had on hand an 80psi sensor so I
   plumbed it into the leading plug positions and cranked it over.
Read the
   sensor output on the scope and got this;

   2 pressure peaks of 71.1psi and 1 peak of 78.2psi at the front rotor.
   The rear rotor read higher than the sensor spec, 85.3psi, but had equal
   pulses and didn't overdrive the sensor output.  RPM was 226.
   What is your take on these readings from a fresh rebuilt eng. with new
   rotor housings and seals?


   Robert LeClercq

   It should run. That is enough pressure. I suspect there is something
   else wrong. Put some auto transmission fluid
   in the housing and let it sit overnight or for a day or too. Could be a
   stuck seal.

   Check the timing for 22 degrees BTDC on all four plugs. Use fresh
plugs.
   Front and back
   rotor are 180 out.

   Then get a six volt battery and wire it in seres with the 12 volt just
   for the starter.
   Apply the 18 volts to the starter.  Limit the time it turns over as one
   can overheat
   the starter motor.

   This is a common scenario. They sit around for years and refuse to
start.
   One or more seals are stuck. Take the exhaust manifold off. Put the
apex
   seal in the exhaust port one at a time and check it with a screw driver
   to see if it moves
   in and out under the influence of the apex seal spring.

   If you have a pressure sensor and it puts out zero to five volts
hook it
   to a Maximte and you will get a wonderful compression recording.

   Here is how to do that.

   Paul Lamar



   It will start quick with a shot of ether or after only 1 min warm
up it starts easy. Race beat suggested only 3% cranking enrichment so I
set that in the ECU. The start advance is only 12 deg with l10 deg
split. Plugs were clean.  It idles ok at 1400 rpm once started. Will try
your suggestions.

   The uP stuff is above my pay grade; my storage scope was perfect
for the test.
   Thanks


   Robert LeClercq


Years ago, I had a R 100 with 40PSI compression. To start it I had to
put a tablespoon of oil in each carb primary throat. Big cloud of smoke.
Had to keep idle up or vacuum would drop and it would stall.

Dale Davies


Paul,

I think the  ign. advance that you suggested is going to fix the start. To ensure a first start, I used the ether. When the coolant temp reached 40C, I tried a restart and it kicked over quick. Tried an hr later and it still started quick. Hopefully no more ether ever again.  Later today I want to send a pic of my target AFR map for any other suggestions.

regards Robert LeClercq


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