Ported Husqvarna 372xpw

[Chainsaw Jim]

I'm trying to give you sound advice. Myself and others went round and round with the topic and quite a bit of testing was done. Windowing the piston does nothing, other than reducing base pressure.

You're really being way too defensive and immature. If you want to learn how to properly port a 372 "which you don't in any way shape or form" myself and others will be glad to help. Or you can dismiss us and stick your head in the sand. The choice is yours.

No offence but advise is not necessary here because I'm just experimenting with this particular idea. I never claimed to be an expert on port work, but contrary to your claim, I do know how to properly port a 372. This is no example of what you would consider as that, but I'm just sharing the experimenting I did on this saw with anyone interested in checking it out. I would have shared step by step through the course of the build but I didn't want comments like yours to alter my thought process on what I was doing.

 

[Chainsaw Jim]

View attachment 440340 Here's an "open port" cylinder for reference.

I'm not confused about what an open port cylinder is supposed to be. The confusion is about the design of the 346,357,372,390 with the transfer ports open through the bottom of the cylinder base, compared to the closed port design with no open base. I just talked to the Husqvarna technical department for dealers and they couldn't tell me exactly what to call it.
So 372 being closed port and me opening it nearly all the way up would make my original comment backwards, but still valid I guess.

 

[Andyshine77]

No offence but advise is not necessary here because I'm just experimenting with this particular idea. I never claimed to be an expert on port work, but contrary to your claim, I do know how to properly port a 372. This is no example of what you would consider as that, but I'm just sharing the experimenting I did on this saw with anyone interested in checking it out. I would have shared step by step through the course of the build but I didn't want comments like yours to alter my thought process on what I was doing.

Sand it is. You're totally full of it, and in you're own little world. Rest assure I'm not the only one thinking that.

Wow!! I got told off for trying to be a nice guy and help someone out. That right there is a whole new kind of...

 

[wcorey]

I'm not confused about what an open port cylinder is supposed to be. The confusion is about the design of the 346,357,372,390 with the transfer ports open through the bottom of the cylinder base, compared to the closed port design with no open base.

Here's an example of a side fed open port.

372 etc. are just a bottom fed closed port. As I stated earlier, it's the presence or lack of the horizontal bridge between the upper/lower transfer openings on the cylinder wall that defines open or closed port (IMO).

It seems to me that there isn't much functional difference between side and bottom fed transfers. In most examples it is simply that the cylinder on the bottom feeder sits lower into the case and incorporates a taller crank case to function as the part that is incorporated onto the cylinder in the taller side fed type cylinder.
Notice the bottom feeders usually have a skirt below the base flange and side feeders normally don't. The base flange just sits relatively higher on the cylinder on one and lower on the other.
There's also some that are a bit of both and some cases where the original side opening sets opened up at the base (by the factory even) to improve performance (930 and 4/590 J'red for example).


Something to point out in piston design is that one with slabbed sides that are dished/channeled can be used interchangeably with a windowed type, just two ways to get a similar result. 7910 new/old piston is a case in point...

 

[Chainsaw Jim]

Is that one of those 266 Gilardoni cylinders?

 

[wcorey]

Is that one of those 266 Gilardoni cylinders?

A 42, very similar to the op 268, just smaller of course and IIRC is a Gilardoni. So close to a 242 it's difficult to tell them apart visually without looking into the bore.
It's a good example of open vs closed, take the vertical divider out of the 42 (or 268) and put in a horizontal bridge, you pretty much have a 242xp (or 268xp).
The port timing is even very close... and there is a bit more 'bulge' on the xp transfers.

 

[MattG]

I'm a bit of a newbie in all this (chainsaw-wise). I had a quick look through

http://edj.net/2stroke/BellPerformanceTuning/Bell Chapter 3.pdf

last night. (I seem to have lost my paper copy :-( ). And I couldn't easily find a definition of the difference between closed and open transfers. From reading stuff on AS, though, I think I have my own idea:

"For a closed port some metal, either at the bottom of the cylinder wall, or at the top of the crankcase, forms the bottom extent of the port. For an open port there is no bottom of the port, but the skirt of the piston effectively forms a moving bottom divider as it travels up and down".

Could someone please confirm whether my idea/definition is correct?

Thanks Matt

 

[SawTroll]

Is that one of those 266 Gilardoni cylinders?

If it is a Gilardoni for that saw family it would be for a 66 or the non-xp/special 268, not for the 266.

 

[wcorey]

"For a closed port some metal, either at the bottom of the cylinder wall, or at the top of the crankcase, forms the bottom extent of the port. For an open port there is no bottom of the port, but the skirt of the piston effectively forms a moving bottom divider as it travels up and down".

Could someone please confirm whether my idea/definition is correct?

Thanks Matt

For that to make any sense at all, it should read something like;

"For a closed port some metal, either at the bottom of the upper section of the transfer port on the cylinder wall, or at the top of the crankcase, forms the bottom extent of the upper transfer port. For an open port there is no bottom of the port, but the skirt of the piston effectively forms a moving bottom divider as it travels up and down".

Though I can't think of an instance were one makes the crank case part of the cylinder wall...

 

[SawTroll]

For that to make any sense at all, it should read something like;

"For a closed port some metal, either at the bottom of the upper section of the transfer port on the cylinder wall, or at the top of the crankcase, forms the bottom extent of the upper transfer port. For an open port there is no bottom of the port, but the skirt of the piston effectively forms a moving bottom divider as it travels up and down".

Though I can't think of an instance were one makes the crank case part of the cylinder wall...

I think that both you and mattG is making it a bit complicated. The point is that on a closed transfer, the cylinder wall covers part of the transfer, creating an intake and an output opening, instead of a transfer that is open all the way.

Why the common expressions are closed port/open port, instead of the more correct closed transfer/open transfer is beyond me.

 

[tlandrum]

o look a squirell >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

 

[MattG]

For that to make any sense at all, it should read something like;

"For a closed port some metal, either at the bottom of the upper section of the transfer port on the cylinder wall, or at the top of the crankcase, forms the bottom extent of the upper transfer port. For an open port there is no bottom of the port, but the skirt of the piston effectively forms a moving bottom divider as it travels up and down".

Though I can't think of an instance were one makes the crank case part of the cylinder wall...

Thanks Bill

 

[Chainsaw Jim]

A 42, very similar to the op 268,

If it is a Gilardoni for that saw family it would be for a 66 or the non-xp/special 268, not for the 266.

Are you saying Gilardoni didn't make a 266 cylinder?

 

[SawTroll]

Are you saying Gilardoni didn't make a 266 cylinder?

No, I am saying they didn't make an open port one for the 266. The ones for the 66 and 268 will of couse bolt on to a 266 as well, but they weren't made for that model, and may require other changes to the saw.

Gilardoni made closed port ones for the Jonsered 670 though, so likely for the 266 as well.

 

[Chainsaw Jim]

I've been running it after putting a green tube filter on it and it has continued to improve. It's already faster than in the video. I'll be putting it up against an ms660 today to see how it compares. I'm also going to run it with an ms460 with a brand new top end. Videos coming soon after.

 

[bwalker]

I've been running it after putting a green tube filter on it and it has continued to improve. It's already faster than in the video. I'll be putting it up against an ms660 today to see how it compares. I'm also going to run it with an ms460 with a brand new top end. Videos coming soon after.

Unless your time is worthless why not just send it to a reputable tuner as the price is slight? I no, I no, it's en vogue to port a saw your self on this site. However IMO there is no glory in producing a POS at worst and something not quit as good at best.

 

[Chainsaw Jim]

Unless your time is worthless why not just send it to a reputable tuner as the price is slight? I no, I no, it's en vogue to port a saw your self on this site. However IMO there is no glory in producing a POS at worst and something not quit as good at best.

Jeezus dude, you kind of come off as obsessive over this. Why are you so offended?

 

[tree monkey]

I've been running it after putting a green tube filter on it and it has continued to improve. It's already faster than in the video. I'll be putting it up against an ms660 today to see how it compares. I'm also going to run it with an ms460 with a brand new top end. Videos coming soon after.

don't let these guys tell you what works and what don't.
thinking outside the box wins races.
windowing pistons works for me.

 

[Chainsaw Jim]

Well it took a while for me to get the video editor figured out. I'm not too proud of myself for the lack of camera alignment.
Both saws are running 3/8 .050 32" bars and a newer chisel chain with only one sharpening after factory. The woods ported ms660 magnum was built by Wildwood saw shop in Fortuna California.

 

[tree monkey]

looks good to me