Questions about porting gurus?

[Huskybill]

please I’m looking for the guys who do porting not novices. I had the husqvarna ported rep piston and cylinder in my hand. I was all over it measuring it before I assembled the saw. The exhaust port was raised 1/8” and the intake port was lowered 1/8” when comparing it to a stock cylinder.
Don’t try this at home. I also noticed the piston skirt was cut 1/8” shorter? What do you gurus think that does on the bottom of the piston in relationship to the lowered and raised ports?
Cutting the piston skirt, it does nothing to the exhaust port, but influences the intake. Do you think the intake port can open too early?

Please no peanut gallery hackers it’s strictly business.

 

[NSEric]

Im no guru but I know cutting the pistons intake skirt shorter opens the port sooner giving you more intake timing. Most saws like the intake to open at 75-80 degrees after bottom dead center.
Taking 1/8 off the port and the piston is extreme, did the saw spit back gas into the air filter badly? This is a sign of the intake being open too long.
This stuff is all over youtube, there's tons of saw builds to check out.
One of the more common builds that works on a lot of saws is to cut .020-.030 off the pistons intake skirt, ditch the base gasket and gut the muffler, leaving the other ports alone, its the best bang for you buck porting wise.

 

[wcorey]

While I don't disagree with anything on NSEric's response, you really need the opening or duration numbers in degrees if you expect to get a meaningful answer...
Is the piston shortened all the way around or just on the intake side?

 

[Huskybill]

All the way around it’s shortened. There was a full skirt piston in the 2100 in the beginning I can’t remember which piston it was.

On another note,
I do notice on some two strokes the piston skirt on the intake side doesn’t clear the port by more than 3/32” in TDC. I figure the u shaped remains port should be knotches out in the piston.

 

[Andyshine77]

The only way to know where anything is at, is to degree the engine, that will give you the port timing.

 

[cuinrearview]

Please no peanut gallery hackers it’s strictly business.

@huskihl

 

[full chizel]

Bill i thought you were a porting guru?? I saw your thread about teaching people about porting. I’m confused.

 

[full chizel]

Feel free to ask any question you want. I just thought you knew it all because you were trying to teach others.

 

[full chizel]

I’m not accusing you of doing anything wrong or stepping on anyone’s toes. I just thought you were one of the big porters here based on your porting thread. Sorry for the confusion.

 

[huskihl]

@huskihl

Peanut gallery ×
Hack ×

Pro ?

 

[huskihl]

Pistons are already short. The intake side always wears thin after a good many hours, therefore I've never shortened one. I've built some saws where the intake was in the 170-180° duration range. They tend to be lazy to rev up due to lost case compression. Most of mine end up at 155-165° duration.

1/8" on the intake skirt of a 2100 is probably about 10-12° duration

 

[cuinrearview]

Peanut gallery ×
Hack ×

Pro ?

Guru

 

[huskihl]

Guru

Pffft

 

[huskihl]

Here we go again I guess.

No peanut gallery hackers, no hammer and chisel.....no cavemen Lol

You're **** out of luck. That's all that's left here

 

[cuinrearview]

 

[cuinrearview]

And

 

[drf255]

 

[cuinrearview]

Haha nice! That reminds me of the first Dolmar 5100s I got into. Early on they had issues with crank bearings spinning in their pockets. The shop manual after that included "use adhesive" in the instructions for a bottom end re-build. The locked up saw I got had been done with that type of Loctite, not the proper sleeve retainer meant for the application. It had vaporized and gotten into every bearing. Pretty cool...

 

[drf255]

I’m a peanut gallery member myself, not a guru.

As said above, you really can’t tell much without a degree wheel. Use a ring to find port edges with a pick, it’s the most accurate way for transfer and exhaust ports I’ve been told.

Also, “Porting” is really supposed to be purpose specific. A race saw built to go through a 12” cant of poplar with have different port timing than a saw built to run a 5 ft bar all day. So, even the best porting guru can build a dud if it’s built for the wrong purpose (or if the end user changes it’s purpose).

 

[cuinrearview]

All I build are duds