> Hi Paul and All,
     > Couple of Photos for Your Up-Date,
     > Have changed the pulleys to install the 36-1 tooth Edis wheel,
     > Got things taged together, rough fit for vibration test run.
     > Radiator is 10 x 12 x 1.25 Avid Flyer part.
     > Couple of questions,
     >
     > 1. Whats the deal in the exhaust port,
     > the small down angle tube retained by roll pin?
     > 2. Do I stay with stock 12A timing useing Edis-4 Setup.
     > Leading 0 TDC
     > Trailing 20 ATDC
     > Best Regards
     > Rolland

    Rolland,
    What sort of carb is that - it looks like an old Posa.
    I like your engine brackets and do you have a damper on that PSRU.
    What sort of PSRU is that?
    George (down under)


    George,
    Engine is from E-Bay No history/Info.
    See photo's of HD PSRU has no damper.
    Carb is POSA also have Makuni 42mm.
    Question is dynamic balance, I need to do test run!
    Rolland (Philippines)
    Kitfoxes RP-S135/S2804

Rolland,
The Posa is the forerunner to many slide carbs of today.
.
I'm doing my own slide carb and some of the slide carb problems have to do
with sticking slide. I believe I have solved that by using bearings.
The Aero Carb is a slide as is the Ellison and many more.

Do you need some advice on dynamic balance of a single rotor, if so I am
more than willing to share advice given to me. I am also developing a single
rotor.
George (down under)

Well lets hear it.

Paul Lamar ...No rotor no motor.

Paul, Rolland and Richard.
Advice to me is that dynamic balance should include the weight of a full
rotor of oil, all rotor seals except the apex seals and springs. It is
suggested that the Apex seals and springs weight is taken by the rotor
housing and therefore not part of the rotating mass. There's not much in it
either way.

The different rotors have different cavities and therefore carry different
amounts of oil, so each rotating assembly should be checked individually.

I intend using an RX8 rotor and for my own benefit will check to see how
balanced the rotor is in itself. The RX7 rotors have the balancing letters
stamped on them.

Now I have measured the RX8 and RX7 rotors and found about 3mm difference in
the depth of the area under the apex slot, the Rx7 being deeper. I have cut
3mm apex seal slots in the RX8 rotor and there appears to be plenty of metal
depth left, for the necessary strength in this area. I mention this as there
appears to be a difference of opinion, in if this can be done or not.

Now if you disagree, as some do, all I can say is that is best advice
available to me.
George (down under)


The rotors are never completely full of oil and the amount of oil in them
varies as they make their way around the inside of the engine.
-- 
Paul Lamar ...No rotor no motor.

Hi Guys;
The rotor are supposed balanced at the factory - hence the balance holes
near the tips.
I believe Mazdatrix confirmed dynamic balance here.
Most balancing I have heard of is done without the seals for the reasons
described above.
The rotors have a weight code A-E stamped on the gear side - these
should be measured with
a gram accuracy scale anyway - consider yourself warned.
There are also Japanese Kanji? characters - if you know their meaning -
many people would like to know :)

I have measured the 100% full static oil volume of several rotors, it is
a messy affair.  Probably near valueless...
Dynamic measurement is probably even more fun with a partner!
I posted some Mazda Factory Racing links and other info a while back.
The "magic number" that balancers will not share is the dynamic amount
of oil in the rotor at various conditions, rpms...
IIRC - 100% oil volume of a rotor appears to track quite well based on
the CR and rotor weight assuming a density for iron=7.86g/cc
(last digit seemed to be off).  The problem is that there it is even
more difficult to determine balanced internal distribution -
probably doesn't matter much anyway...
IMHO - race clearancing is of more value if you plan to run higher rpm.

George, have you checked if the apex seals slot is hardened in any way?
that area appears
to be very soft on the rx7 rotors.
I have heard of racers running rx7 seals in the rx8 rotors.

Cheers
Cary



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