2 Cycle Setup on a Pipe

randy10926 at comcast.net randy10926 at comcast.net
Wed Mar 31 12:24:28 AKST 2004 

Must be nice to get to the field with an hour.  

Sounds like I should try this with my 145 and see what I get. I think I am getting more than 7700 rpm on an APC 17X12 narrow with my 145.

Randy
> Reasonable question!
> The box width, or 5 seconds, or 50,000 miles: whichever comes first.
> Did it not richen at all, or just not enough to burble?
> I take it that you got out and flew during the last hour.
> Dean
> 
> -----Original Message-----
> From: Brian Young [mailto:b4598070 at yahoo.com]
> Sent: Wednesday, March 31, 2004 2:37 PM
> To: discussion at nsrca.org
> Subject: RE: 2 Cycle Setup on a Pipe
> 
> 
> Ok, how long is a long shallow dive at full throttle.
> 10 seconds, 30, ......
> 
> I did this w/ my 26.5" setup for about 5-10 seconds
> and no burble.
> 
> --- Dean Pappas <d.pappas at kodeos.com> wrote:
> > Hello Randy and Bob,
> > The pipe length from piston face (the plane of the
> > exhaust port) to the reflector baffle is
> > approximately proportional to the exhaust timing.
> > The suggestion to start by shortening the 160 pipe
> > by 0.5" to 1"  Dave gave you is based on this, and
> > his running of both engines. You do not want to
> > shortenn for maximum ground RPM, you want to start

> > long, and fly. After verifying the "correct" needle
> > setting, try a long 5-degree full throttle dive. If
> > the engine gurgles rich, shorten a bit, and try
> > again. When the engine no longer richens, in the 5
> > degree dive, stop. Any further shortening sacrifices
> > flexible running characteristics for only the
> > tiniest real horsepower inprovement. 
> > Dean
> > 
> > -----Original Message-----
> > From: Brian Young [mailto:b4598070 at yahoo.com]
> > Sent: Wednesday, March 31, 2004 1:55 PM
> > To: discussion at nsrca.org
> > Subject: Re: 2 Cycle Setup on a Pipe
> > 
> > 
> > Randy Im at 26.5 from the exhaust flange right now.
> > The 1.60 runs fine at this length, but im only
> > getting
> > 7700 rpm on a 17x12 which I think is low.
> > 
> > I had suggestions of 27 inches for a target from the
> > 1.45, less about .5"-1" for the 1.60. But on Ed
> > Hartleys website I notice someone running as long as
> > 30". 
> > 
> > FWIW the exhaust timing I measured on the 1.60 is
> > 140
> > degrees, and on the 1.45 is 147.
> > 

> > --- randy10926 at comcast.net wrote:
> > > Does anyone else have the ppe lenght for the Webra
> > > 160?  Hos much change would be need to replace my
> > > 145 with a 160.
> > > 
> > > Randy
> > > > Don't know, Randy.  I don't know the timing of
> > the
> > > Webra 160 and no one has
> > > > let me borrow one.  I own the Webra 145, OS140,
> > > Mintor 170 and regularly use
> > > > these in testing.
> > > > --Lance
> > > > 
> > > > ----- Original Message ----- 
> > > > From: <randy10926 at comcast.net>
> > > > To: <discussion at nsrca.org>
> > > > Sent: Tuesday, March 30, 2004 3:17 PM
> > > > Subject: Re: 2 Cycle Setup on a Pipe
> > > > 
> > > > 
> > > > > Is the pipe length for the Webra 160 the same
> > as
> > > for the Webra 145?
> > > > >
> > > > > Randy
> > > > > > Ditch the MC carb during testing and put a
> > > regular 1.45 carb on it.  The
> > > > > > bench mount it.  I have been testing
> > AeroSlave
> > > carbon pipes for a year
> > > > now
> > > > > > and have a great setup for quickly getting
> > > tuning length and rpms.  I

> > > > have a
> > > > > > "trombone" made from two pieces of silicon
> > > coupler with a short length
> > > > of
> > > > > > aluminum header pipe in between. By starting
> > > with everything extended to
> > > > the
> > > > > > extremes and sliding the whole mess together
> > I
> > > can watch a tach and take
> > > > > > readings real time.  Takes about 5 min to
> > get
> > > the numbers and then setup
> > > > the
> > > > > > flying lengths.
> > > > > > --Lance
> > > > > >
> > > > > > ----- Original Message ----- 
> > > > > > From: "Brian Young" <b4598070 at yahoo.com>
> > > > > > To: <discussion at nsrca.org>
> > > > > > Sent: Monday, March 29, 2004 3:16 PM
> > > > > > Subject: 2 Cycle Setup on a Pipe
> > > > > >
> > > > > >
> > > > > > > I have recently been tuning on my exhaust
> > > and have a
> > > > > > > basic understanding but want some more
> > > information.
> > > > > > >
> > > > > > > I have a Webra 1.60 w/ MC carb and a Webra
> > > pipe w/ a
> > > > > > > disk baffle.
> > > > > > >

> > > > > > > Im gradually shortening this pipe setup
> > > hoping to hit
> > > > >
> > > > > > > the correct length. The problem I find
> > with
> > > this setup
> > > > > > > is the MC carb doesnt lend itself to a
> > test
> > > stand
> > > > > > > since the mixture is servo controlled. So
> > I
> > > shorten
> > > > > > > pipe and fly, shorten and fly.
> > > > > > >
> > > > > > > The thing Im most curious about is if you
> > > had a setup
> > > > > > > no one else has how do you determine a
> > close
> > > first
> > > > > > > guess for the pipe length if you want to
> > cut
> > > down the
> > > > > > > trial and error? I had a starting point
> > but
> > > was just
> > > > > > > puzzling over this.
> > > > > > >
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