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chadihman
Addicted to ArboristSite
How low? Just ported a 660 jug last night. The darn jug had a huge lip on the bottom of the intake port. When I checked stock #s the lip was there making it look higher. After cutting squish and base I have the exhaust just where I want it but after porting it and removing the ugly lip it's now at 90° on the intake. Didn't run it yet. Hopefully it didn't hurt it.
Mastermind
Work Saw Specialist
85 is where the 661 is at after machine work.......and without touching a burr to the port. I like to see about 40 degrees of primary compression. The 661 ends up with 35.
When I have a port that is at a height I consider too low, or high, I will not widen that port at all either. We gain time/area in two ways.....either by adding duration, or width.
When I have a port that is at a height I consider too low, or high, I will not widen that port at all either. We gain time/area in two ways.....either by adding duration, or width.
RiverRat2
Serio Tree Freak
That is an excellent answer Master Chimp Miester!!! to the Riddle "Why Witches cant have babies?"
But the one I was told as most correct Is: Because warlocks have Hollow-weenies!!!!
Trx250r180
Saw polisher
What does this mean in english ?
chadihman
Addicted to ArboristSite
85 deg before top dead center is where the intake port starts to open in direction of engine travel. 35 or 40 would be its gulp of air fuel from tdc to closing of intake port correct?
Trx250r180
Saw polisher
I have not a clue ,that's why i give the monkey 300 bucks to do it
Brian, just think of a port working like a cam, except the opposite. The width of the port is like lift, and the height of the port is like duration.
chadihman
Addicted to ArboristSite
Got the 35-40 wrong for primary compression. Im with Brian what do speak of master? Spent 5 min staring at a degree wheel moving it all over and couldn't figure it out.
Trx250r180
Saw polisher
My saws do not have push rods
It's overhead cam!
And what do U mean UR saws, that's gonna be my saw!
AAA
AAA...........YES thats the new stihl concept but you must wait a .............. little. Just the 63cm bar cost 400 euros , also its not 661 its a 441 with a on-off switch, some carbon covers and carbon handle. nothing special, when they make a carbon crankcase then its a special now its only a carbon covers.
Yes ... but UR a party pooper!!! (Just kidding, thanks for the info)
Mastermind
Work Saw Specialist
Picture this in your mind........
The piston is traveling down the bore.......it's skirt passes the intake port's floor. That seals off the intake and begins the point of case/primary compression. The piston continues downward squeezing the mixture of fuel and air. That squeeze goes on until the transfer ports begin to open.
Intake closes at 85 degrees........transfers open at 120 degrees. 120 - 85 = 35.
Mastermind
Work Saw Specialist
This whole process gives us 5 points, or specs to consider when building a two stroke, piston ported engine.
1: Exhaust Height
2: Transfer Opening Point
The product of the interaction of those is 3: Blowdown.
4: Intake Closing Point
2: Transfer Opening Point
The product of that interaction is 5: Primary Compression.
1: Exhaust Height
2: Transfer Opening Point
The product of the interaction of those is 3: Blowdown.
4: Intake Closing Point
2: Transfer Opening Point
The product of that interaction is 5: Primary Compression.
chadihman
Addicted to ArboristSite
Gotcha!
ncpete
ordained Dude
- Joined
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Muddy. Clearer, but still muddy. I will clearly have to find a "how it works" video.
big t double
Addicted to ArboristSite
Now I'm really confused on how intake timing is determined 
I always figured it was after bottom dead center when it opens...then I've seen before top dead center when it opens...now it's after top dead center when it closes Dag I'm too simple for this stuff hahaha...I guess I need to get a proper degree wheel and start playin around.
I always figured it was after bottom dead center when it opens...then I've seen before top dead center when it opens...now it's after top dead center when it closes Dag I'm too simple for this stuff hahaha...I guess I need to get a proper degree wheel and start playin around.
