Very sweet!

[John Soliday]

To add a bit of detail, the old port (and reed valve for that matter) 2
strokes also always had roller bearing connecting rods, top and bottom.
They were lubricated ONLY by the oil in the fuel/oil mix that was floating
around in the bottom end.  Amazing they lasted as long as could.  No
pressurized oil and plain bearings in a port 2 stroke!

Cheers,

John (ex RZ350 racer)

-----Original Message-----
From: gpzlist-bounces at micapeak.com [mailto:gpzlist-bounces at micapeak.com] On
Behalf Of Dave Daniels
Sent: Friday, November 20, 2009 11:56 AM
To: GPZ List
Subject: Re: Very sweet!

Thanks for clearing it up for me. I had not heard this before.

--- On Fri, 11/20/09, scapco at ecentral.com <scapco at ecentral.com> wrote:


From: scapco at ecentral.com <scapco at ecentral.com>
Subject: Re: Very sweet!
To: "GPZ List" <gpzlist at micapeak.com>
Date: Friday, November 20, 2009, 1:49 PM


When the piston rises, fuel is sucked in to the lower 
crankcase, thus the reason 2-strokes have oil in the fuel 
mix.  When the piston goes down, the piston skirt seals off 
the intake and the pressure forces the air/fuel mix 
up "ports" that are in the sides of the cylinder and on top 
of the piston.  When it rises again, it seals these ports 
off and compresses the fuel.

The old 2-strokes like this were called "piston port" 
because the piston and port height controlled the "timing", 
essentially what the cam does.  The newer 2-strokes, 
employee a reed valve in the back to seal off the intake 
instead of the piston skirt.  This increased the bottom end 
substantially.  In fact, the older single cylinder 2-
strokes from the 60's and very early 70's were capable of 
starting backwards and it did happen that some poor sucker 
would be on a starting line and when the gate dropped his 
bike would go backwards.

Charles S.

>Then how does the fuel get into the combution chamber? 
That makes no sense.
> 
> --- On Thu, 11/19/09, Steven Bixby <steven at bixbys.net> 
wrote:
> 
> 
> From: Steven Bixby <steven at bixbys.net>
> Subject: Re: Very sweet!
> To: "GPZ List" <gpzlist at micapeak.com>
> Date: Thursday, November 19, 2009, 11:06 PM
> 
> 
> Two strokers feed the fuel in below the pistons, whereas 
four-strokes feed
> them into the head.
> 
> I miss my old Kaw 250 duallie from about 1976, maybe?   I 
forget. 
> I
> thrashed that bike completely, though.  I probably put 
about 5K miles a
> summer just running around the rural neighborhood, 
helmetless, jacket-less
> and occasionally shoeless, and strangely, I survived it.
> 
> On Thu, Nov 19, 2009 at 7:48 PM, Dave Daniels
> <dwaynedaniels at sbcglobal.net>wrote:
> 
> > I can't get over how low the carbs sit. Also, I see a 
steering damper. Is
> > that stock?
> >
> > --- On Thu, 11/19/09, coldinvt at gmavt.net 
<coldinvt at gmavt.net> wrote:
> >
> >
> > From: coldinvt at gmavt.net <coldinvt at gmavt.net>
> > Subject: Re: Very sweet!
> > To: "GPZ List" <gpzlist at micapeak.com>
> > Date: Thursday, November 19, 2009, 10:08 PM
> >
> >
> > I knew Scapp would be droolin'... I am too though... 
That thing's sweet!!
> >
> >
> > > Very nice indeed, That gives me a woody.  10 years 
ago I did
> > > a frame up restoration on a 1973 exactly like this one
> > > except mine was the rare factory metallic purple.  
What I
> > > wouldn't do to have that back again.  Mine came out 
nice,
> > > but this one is nicer.  I also owned a new 1975 H1F 
(the
> > > 500), a 1974 H1 and a 1976 KH-500, all 2-stroke 
triples.
> > > Those were the days...
> > >
> > > Charles S.
> > >
> > >
> > >> http://nashville.craigslist.org/mcy/1472397025.html
> > >>
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
>