2 Cycle Setup on a Pipe

David Lockhart DaveL322 at comcast.net
Thu Apr 1 12:23:39 AKST 2004 

My experience -
145 on muffler is ok at 7500.  With pipe, 8000+ is friendlier.
160 has lower timing and is ok 7400-8000 on either muffler or pipe.

Dave

----- Original Message -----
From: "Lance Van Nostrand" <patterndude at comcast.net>
To: <discussion at nsrca.org>
Sent: Thursday, April 01, 2004 12:44 AM
Subject: Re: 2 Cycle Setup on a Pipe


> 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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