Venturi sizes...

[Bootlegger]

  Fellow's sometime back I posted the fact that I was getting over 9 min. run time on a RO Jett 40 using 10% fuel w/22% oil.
  I measured the venturi a few minueta ago and it measured .189 thou, so I opened it up to .193 for some more runs.
  Those of you using this engine would you tell me what your venturi measures and what sort of fuel millage that your getting    T I A, Gil

[Bill Little]

  Fellow's sometime back I posted the fact that I was getting over 9 min. run time on a RO Jett 40 using 10% fuel w/22% oil.
  I measured the venturi a few minueta ago and it measured .189 thou, so I opened it up to .193 for some more runs.
  Those of you using this engine would you tell me what your venturi measures and what sort of fuel millage that your getting    T I A, Gil

Gil,

How MUCh 10%/22% fuel are you using for the 9 min. run?  4 oz., 4 1/2 oz, 5 oz., ?? ?? ??

[Bootlegger]

   Bill, That would be a help !!!  I am using 5 oz of 10% Powermaster
 Fuel. I am glad that you caught that... 

[john e. holliday]

I am using 4.75 ounces of fuel on my RO-Jett 40 BSRE with stock venturi and the mini pope muffler.  haven't checked the venturi as it works with a decent 4-2-4 break.  Have fun,  DOC Holliday

[Bootlegger]

Doc, This is a rear exhaust engine and I have run an 11.5x4 prop on it using only the muffler that comes with the engine.
  I thought that the engine was "straining" somewhat at 9600-9800 rpm, I tried to needle it a little higher and it said no...Do you know what venturi size yours has in it ??  Sure do thank you for your answer...Gil

[Mike Haverly]

Gil, I have run my Ro-Jett (on a pipe) with that same venturi (.189), 10/22 Powermaster fuel, and launch at 9500 RPM.  Any faster than that and the airplane was way too fast.  At that rpm and that prop I use a full five ounces for a pattern with about five laps left.  In Canada this past summer I was able to manage the seven minute FAI rule by removing 1/2 ounce.  I'm now using a Bolly 11.3 X 3.8 and launching at 10,200 rpm and using 4 3/4 ounces. Oh yeah, the airplane is my Oriental Plus.
11 1/5 x 4 APC should be a good choice.

Mike Haverly

[john e. holliday]

Doc, This is a rear exhaust engine and I have run an 11.5x4 prop on it using only the muffler that comes with the engine.
  I thought that the engine was "straining" somewhat at 9600-9800 rpm, I tried to needle it a little higher and it said no...Do you know what venturi size yours has in it ??  Sure do thank you for your answer...Gil

Well you made me do it.  I have pulled the instructions and reread them again for the umpteenth time.  It states the engine is supplied with a venturi drilled with a #12 drill size hole(.189).  It also states that venturi's are available in case you want to make a larger hole.  The prop Richard told me to use and it works great on a heavy Accentor is the Windsor 11.5X4.5(could be Thunder Tiger prop) too lazy to go look in box as I have not unloaded from last weekend.  I am also using all synthetic Power Master fuel 10% nitro, 22% oil.  Fuel per personal talk with Richard.  Have fun,  DOC Holliday

[Garf]

If its grey, it's the thunder tiger cyclone. I'm running them myself.

[Howard Rush]

I get about 6:05 from a 5.5-oz tank on a RO-Jett 65 with 10% nitro, 18-22% oil, near sea level in cool weather.  The venturi diameter is stock.  This seems to be more time than others get with the same amount of fuel.

[Bootlegger]

   Thanks guy's. I opened the venturi up to .193 (.004larger) and hope to soon have that baby in an airplane.
 Again, thanks for the help/suggestions...