2 Cycle Setup on a Pipe

Wed Mar 31 12:58:48 AKST 2004

Hi Brian,
Have I been on the list that much, lately? When things get hopping at work here, you'll hear less from me.
Fixing the fuel curve is the right thing to do: always.
Having the pipe a little long broadens the mid-range mixture sweet spot.
You just have to keep from going too far, causing the engine to lose power and fatten up at high in-air RPM.
You never want the pipe too short, as the sweet spot gets narrow and may disappear altogether.
Too short (depending on pipe design and engine timing) may be the length that produces the best on-ground RPM.
later,
	Dean

-----Original Message-----
From: Brian Young [mailto:b4598070 at yahoo.com]
Sent: Wednesday, March 31, 2004 4:39 PM
To: discussion at nsrca.org
Subject: RE: 2 Cycle Setup on a Pipe

Maybe Dean can discuss this too.

I can tell you on my 1.45s I reduced the fuel pressure
to cure a midrange richness. I know others who did the
same. By doing this I was able to achieve a great
running engine. I may have been skinning the cat the
other way. 

--- randy10926 at comcast.net wrote:
> 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
> > > > > > >
> 
=== message truncated ===

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