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#Post#: 40718--------------------------------------------------
Re: Step in the exhaust port
By: Chainsawrepair Date: May 28, 2014, 4:56 pm
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[quote author=aclarke link=topic=3591.msg40717#msg40717
date=1401313967]
I worked on a P100 that had a 1/4" grove cast into the top of
the exhaust port roof/cylinder plating. It was oem, never
learned the reason why Partner did this but is suspect it was to
start the blowdown event earlier while still maintaining the
torque associated with low exhaust height...
Adam
[/quote]
I swear I remember some folks trying that on racesaw builds too.
#Post#: 40719--------------------------------------------------
Re: Step in the exhaust port
By: aclarke Date: May 28, 2014, 4:59 pm
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Tim, might be worth testing this stepped port theory in the near
future with some AM jugs? I'd be game on contributing a cylinder
or two plus the machining if any other members would be
interested in doing the work involved with swapping jugs and
testing. Maybe try a few other ideas with the same jugs...
#Post#: 40720--------------------------------------------------
Re: Step in the exhaust port
By: 1manband Date: May 28, 2014, 6:13 pm
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panheads also ironheads to '86, had them as cast from the
factory.... the exhaust pipes, were clamped on the outside of
the exh spigot of the head.
-joe
#Post#: 40726--------------------------------------------------
Re: Step in the exhaust port
By: sharkey Date: May 29, 2014, 6:39 am
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Here is an interesting article that explains the process.
HTML http://www.circletrack.com/enginetech/ctrp_1008_intake_reversion/
#Post#: 40742--------------------------------------------------
Re: Step in the exhaust port
By: 1manband Date: May 29, 2014, 3:43 pm
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[quote author=sharkey link=topic=3591.msg40726#msg40726
date=1401363569]
Here is an interesting article that explains the process.
HTML http://www.circletrack.com/enginetech/ctrp_1008_intake_reversion/
[/quote]
good read.
in the older bikes....exactly that.
there used to be an aftermarket part, made for evo's that
claimed to prevent this. cone shaped thing....placed into the
exhaust pipe. thing is, evo's did not have that problem.
-joe
#Post#: 40784--------------------------------------------------
Re: Step in the exhaust port
By: Gatekeeper Date: May 30, 2014, 11:04 pm
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There's a west coast shop that puts them in work saws also. Not
sure if they really help or hurt. I've not done any yet in any
saws. Figured I don't need that last 2-5% for cutting firewood.
#Post#: 40785--------------------------------------------------
Re: Step in the exhaust port
By: KilliansRedLeo Date: May 31, 2014, 3:39 am
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[quote author=aclarke link=topic=3591.msg40719#msg40719
date=1401314345]
Tim, might be worth testing this stepped port theory in the near
future with some AM jugs? I'd be game on contributing a cylinder
or two plus the machining if any other members would be
interested in doing the work involved with swapping jugs and
testing. Maybe try a few other ideas with the same jugs...
[/quote]
Adam, I'm game for that! I was just toying with another idea,
and I have a saw ready for a top end. PM me with a number and I
will give you a call to discuss. I can also supply a couple of
AM jugs.
#Post#: 40796--------------------------------------------------
Re: Step in the exhaust port
By: farmboy Date: May 31, 2014, 3:39 pm
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I cut one in a Husky 55, widened and polished w/DP muffler.
Runs good but haven't run a stock one to see difference.
Shep
#Post#: 40797--------------------------------------------------
Re: Step in the exhaust port
By: KilliansRedLeo Date: May 31, 2014, 4:08 pm
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I'm thinking about something else to try also, if I can figure
out how to do it. I would like to try a pair of crankcase
stuffers in a 365/72 saw. Sort of like the 575/76 have. Anyone
have any ideas?
#Post#: 40803--------------------------------------------------
Re: Step in the exhaust port
By: aclarke Date: May 31, 2014, 6:46 pm
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Didn't husky add a plastic stuffer onto one of the 3 series Saw
crankshafts? You can also machine a ring that presses onto
each crank half and fill the "voids" between the Bell and Big
end pin with epoxy. Marcel Vincent and others have used this
method on race saws and it works well.
I think the 372 would respond well to this but the port timing
might have to be altered slightly to deal with the higher
crankcase pressure.
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