2 Cycle Setup on a Pipe

Lance Van Nostrand patterndude at comcast.net
Wed Mar 31 20:44:00 AKST 2004 

Careful Randy.  Dean has good information, but these engine tuning issues
are not the result of one parameter.  Webras have been known to have their
pump pressure too high and this can contribute to midrange burble too.
  the tuning numbers I gave you assumed you were propped for 8000.  I don't
think the Webras run as well when propped below this.
--Lance

----- Original Message ----- 
From: <randy10926 at comcast.net>
To: <discussion at nsrca.org>
Sent: Wednesday, March 31, 2004 3:27 PM
Subject: RE: 2 Cycle Setup on a Pipe


> Man that describe my 145.  It is my second one and still low mileage, but
mid range is a problem.
>
> Randy
> > You might still wish to shorten the pipe, be on the lookout for
mid-throttle
> > hysteresis. If you are not flying at mid throttle for most of your level
lines,
> > you might not be looking for this. The symptom is an inconsistent power
level
> > when you pull back or throttle up to the same middle-stick position.
> > Hope this helps,
> > Dean
> >
> > -----Original Message-----
> > From: Brian Young [mailto:b4598070 at yahoo.com]
> > Sent: Wednesday, March 31, 2004 4:11 PM
> > To: discussion at nsrca.org
> > Subject: RE: 2 Cycle Setup on a Pipe
> >
> >
> > ;)
> >
> > I tried this over the past weekend, Ive seen you
> > mention this before. It didnt richen at all.
> >
> > --- Dean Pappas <d.pappas at kodeos.com> wrote:
> > > 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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