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Fitting parmakit
Posted: Sat Dec 10, 2016 10:12 pm
by ducksta
Hi guys vespa px 125 engine, 60 mm crank fitting a Parmakit the one designed for a 57 mm rod so for low down torque how am I to pack the barrel what goes on bottom what on top my thoughts where the 6 base gaskets at the bottom then a 3 mm head gasket?
Re: Fitting parmakit
Posted: Sat Dec 10, 2016 11:46 pm
by ducksta
Anybody?
Re: Fitting parmakit
Posted: Sun Dec 11, 2016 12:07 am
by Darrell Taylor
Set the cylinder up with base packers until the piston crown is level with the the base of the transfer ports at bottom dead , then do the top of cylinder head gasket choice to obtain the recommended squish or approx 1.2mm on a 60 stroke ,,,, providing the compression ratio is acceptable ,,the exhaust will dictate more so the riding characteristic although a peaky pipe can be tamed a little by running lower durations (eg no base gaskets)
Re: Fitting parmakit
Posted: Sun Dec 11, 2016 10:17 am
by Jack221
If you give me some measurements, I'll do some sums for how I think to pack the barrel for max torque.
Top of exhaust port to top of barrel
Top of a main transfer port to top of barrel
Re: Fitting parmakit
Posted: Sun Dec 11, 2016 6:56 pm
by Morgan
Would knowing what type of exhaust is being used effect how you would set the barrel and would any port work be required ?
Re: Fitting parmakit
Posted: Sun Dec 11, 2016 7:22 pm
by drunkmunkey6969
Morgan wrote:Would knowing what type of exhaust is being used effect how you would set the barrel and would any port work be required ?
How long is a piece of string?
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Re: Fitting parmakit
Posted: Sun Dec 11, 2016 7:55 pm
by ducksta
drunkmunkey6969 wrote:Morgan wrote:Would knowing what type of exhaust is being used effect how you would set the barrel and would any port work be required ?
How long is a piece of string?
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4 inches if you cut it at 100 mm thanks for advice not
Re: Fitting parmakit
Posted: Sun Dec 11, 2016 11:01 pm
by ducksta
Darrell Taylor wrote:Set the cylinder up with base packers until the piston crown is level with the the base of the transfer ports at bottom dead , then do the top of cylinder head gasket choice to obtain the recommended squish or approx 1.2mm on a 60 stroke ,,,, providing the compression ratio is acceptable ,,the exhaust will dictate more so the riding characteristic although a peaky pipe can be tamed a little by running lower durations (eg no base gaskets)
Cheers
Re: Fitting parmakit
Posted: Mon Dec 12, 2016 9:13 am
by Morgan
drunkmunkey6969 wrote:Morgan wrote:Would knowing what type of exhaust is being used effect how you would set the barrel and would any port work be required ?
How long is a piece of string?
Hi Dan
Yeah I know what you mean. Maybe I should have phrased it- do you build the barrel around the exhaust or try to find a suitable exhaust once it's built ?
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Fitting parmakit
Posted: Mon Dec 12, 2016 11:21 am
by drunkmunkey6969
Morgan wrote:Maybe I should have phrased it- do you build the barrel around the exhaust or try to find a suitable exhaust once it's built ?
As a pipe (expansion chamber) has a huge influence on any 2-stroke cylinder, my feeling is that you should decide what sort of ride you want FIRST (race, fast road, touring etc) what RPM you want the engine to do its peak work at, what gearing you want to pull at said RPM and buy the correct pipe first.
Then consider what sort of cylinder kit, crank, gearing, carb and ignition will match the end-use profile of what you are trying to achieve.....buy those parts so that you have a 'complete package' of components, all working together towards the same goal, set port timings accordingly, and build the engine.
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