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Engine basics => Engine set up tips => Topic started by: Bob Reeves on October 03, 2006, 07:57:11 AM

Title: ST 51 venturi
Post by: Bob Reeves on October 03, 2006, 07:57:11 AM

I need to make a sprinkler venturi for the ST 51 I am stuffing in the Skylark. The stock venturi is .281 with a .156 spraybar. If my calculations are correct this results in a choke area of .018..

This seems a bit small for a .51 but this is the first .51 I ever played with so what do I know... Are these numbers correct and/or what size venturi is everyone running in the .51?

Thanks

Title: Re: ST 51 venturi
Post by: RandySmith on October 03, 2006, 11:51:04 AM

HI Bob

The ST 51 on a true venturie, works very well  using a #16 or 15 drill bit. or about 175 to 181 thou  hole.  If you need to you can run as small as  a  .169 hole, but any smaller I have found doesn't let the motor cycle, and  also really retards the cycling  so much it becomes a  "dumb" motor, Not knowing when to cycle

Randy

Title: Re: ST 51 venturi
Post by: Bob Reeves on October 03, 2006, 01:32:17 PM

Thanks Randy,

Exactly what I needed to get the ball rolling..

Maybe someday I will be able to afford a real PA engine  :)