engine port timing

[jacob711]

i am going to build a tuned pipe for my 28cc weed wacker motor that is
going into a boat, im not sure how to measure the exhaust port
timing/duration corectly i know how to use a degree wheel, i have seen
the info in the making a tuned pipe section of this site but it doesnt
make sense.

does the duration start a bottom dead center and finish when the piston
crown reaches the top edge of the port or does the duration start when
the port starts to open and finish when the piston crown reaches the
top of the port


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[A.T.]

refer to "Engines,Plugs,Tuning, Petrol, Turbines, Mufflers, Cleaning, etc"
sun section "Bearings, Metal Working, Mufflers, Tuned Pipes." for several
pages on Tuned pipes. e.g.
The Tuned Pipe - Modifying Your Engine
Tuned Pipes - FAQ - Andy Ellison
Tuned Pipe Designer - JavaPipe: - download calculator
Tuned Pipes - The Technology of (emphasis on RC cars/trucks)
Tuned Pipes - The mystery of - four part series + downloads
Regards
Alan T.
Alan's Hobby Model & RC FAQ Web Links
http://homepages.ihug.co.nz/~atong


"jacob711" <jacob711.2uw7q1@no-mx.forums.yourdomain.com.au> wrote in message
news:jacob711.2uw7q1@no-mx.forums.yourdomain.com.au...
>
> i am going to build a tuned pipe for my 28cc weed wacker motor that is
> going into a boat, im not sure how to measure the exhaust port
> timing/duration corectly i know how to use a degree wheel, i have seen
> the info in the making a tuned pipe section of this site but it doesnt
> make sense.
>
> does the duration start a bottom dead center and finish when the piston
> crown reaches the top edge of the port or does the duration start when
> the port starts to open and finish when the piston crown reaches the
> top of the port
>
>
> --
> jacob711
> ------------------------------------------------------------------------
> jacob711's Profile:
> http://www.modelpowerboat.com/forum/member.php?userid=312
> View this thread: http://www.modelpowerboat.com/forum/showthread.php?t=268
>

[john mc lucas]

Duration is from when the exhaust port,
opens on the down stroke to when the piston
closes the exhaust port on up stroke.
Timing duration can be increased by removing
material from the top edge of exhaust port,till
required timing is achieved.Good Luck,
John.


--
john mc lucas
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