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First 2-stroke port (polish)

zgzmithr

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Hey guys, really cool place here,

so, I am a mechanical engineer that owns a powertrain and rod shop... and i like to tinker and learn, so when i learned of the huztl saw kits, it was a must for me.

so, I am putting a 360 & 440 together for friends, me being me I cant leave something with performance potential alone. Came across Matthew Olson's youtube channel and his attention to detail is right up my ally.

anyways, these saws must be ported for maximum fun ;););).

so i break out my sand paper rolls and my Dotco grinders, planning to just clean the intake and exhaust ports up, exhaust turns out well, opened the outside a bit and smoothed it all out, same with the intake but, made a lil mistake tho. So in my excitement while cleaning up the port, i wound up raising the roof on the intake a few thousandths which does not seem ideal. What says you all? what effect will this have?

thanks guys.
 

Redfin

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Assuming the ring pins are in the same locations as oem the jug is fine.
 

moe589

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so i understand right, that the intake is now a little pulled up?
it means that you lost compression.
for timings you have to pull down the intakes ground.
it's the opposite of what you would do at the exhaust port.
if this is only very little, you will prob. not notice any difference.
 

Redfin

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so i understand right, that the intake is now a little pulled up?
it means that you lost compression.
for timings you have to pull down the intakes ground.
it's the opposite of what you would do at the exhaust port.
if this is only very little, you will prob. not notice any difference.

Primary compression is determined by the duration of the floor of the intake.
 

paragonbuilder

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Like the guys said, if the rings are ok, your are good. If perchance the rings could hang, you can run just the top ring. You may have ended up with a little more intake area, which isn’t bad, if the piston skirt isn’t blocking it. Otherwise you increased case volume by a minute amount. No worries.

Edit: missed you said you could run one ring Dave... [emoji106]

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moe589

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Primary compression is determined by the duration of the floor of the intake.

hello,
of course what happen in the crankcase depends on the intakes ground.
and it's right, that there can be no compression for combustion if any port is open, so it depends lately on the exhaust ports roof, when compression starts.
it is imho overall useless pulling the intakes roof up, this is what i understand, what the threadstarter has done.

salute
 

paragonbuilder

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hello,
of course what happen in the crankcase depends on the intakes ground.
and it's right, that there can be no compression for combustion if any port is open, so it depends lately on the exhaust ports roof, when compression starts.
it is imho overall useless pulling the intakes roof up, this is what i understand, what the threadstarter has done.

salute

We are usually looking for time/area while keeping within certain timings, or opening/ closing of ports. This is why we widen. In the case of the intake, if there is any room from the top of the port to the bottom of the piston skirt at TDC, it is free area raising it up, as long as it doesn’t compromise the rings.


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moe589

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of course area and timings belong to each other.
when i have a cylinder to mod i try it the way area first, timing then.
this works up for now very good.
and of course it's a question which engine is to mod...
i notice it's not that easy to explain overall for me as a german...

salute
 

zgzmithr

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Thanks guys, very knowlegable and really helpful.

I use a timing wheel on my big 4-strokes when building them, installing cam/cams, so I will make an adapter for that wheel to use it on saws!

thanks again you guys!
 

paragonbuilder

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of course area and timings belong to each other.
when i have a cylinder to mod i try it the way area first, timing then.
this works up for now very good.
and of course it's a question which engine is to mod...
i notice it's not that easy to explain overall for me as a german...

salute

No worries,
I see you are new here!
Welcome to OPE!! [emoji41]
 
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