Preparing to port first saw - which one, and what method?

[jacktheripper]

Anyone have one of these laying around? It’s a nylon HD filter. Or any other ideas? Maybe a green weenie could fit under the hood

Pardon Our Interruption...

 

[Stump Shot]

Anyone have one of these laying around? It’s a nylon HD filter. Or any other ideas? Maybe a green weenie could fit under the hood

Pardon Our Interruption...

It should run fine with a new clean HD filter. https://www.hlsproparts.com/HD-type-air-filter-for-Husqvarna-268-272XP-p/h50272.htm

 

[Sloughfoot]

Exhaust 100
Transfers 120
Intake 80

I was shooting for 102 exhaust, but went a little too flat and had to arch the roof a little more

Had my 044 exhaust at 103 and when I took it apart and tweaked it, accidentally went to 101. Still had a lot of torque and a whole lot better acceleration.. Also did other stuff to make it rev quicker so don't know for sure where it came from. Yours will be a whole lot zippier than it was stock regardless.

 

[MemphisMechanic]

let is know how it turned out, once you run it!

It should run fine with a new clean HD filter. https://www.hlsproparts.com/HD-type-air-filter-for-Husqvarna-268-272XP-p/h50272.htm

I second this reocmmendation.

I have redbeard’s foam filter & velocity stack on my 372, and the yellow pleated HD filter on my ported 395. Husky’s HD is fantastic. Very easy to knock the large chips out of and keep clean. Filters really well.

(Especially the HD filter for the 395, which is about law large as the one you find on a 25HP riding lawnmower. )

 

[huskihl]

Testing tomorrow… heat cycled tonight. I can already tell the filter is choking it up. I need a better flowing filter option. It has the pleated HD filter now, but maybe the smaller mesh regular style filter will be better if I can get my hands on a setup. Timing is advanced and muffler is modded, but I also think not enough.

Run it without the air filter and see if it gets better. It could be plugged up, but I doubt it’s the actual air filter design. Only one I’ve really had trouble with is the 026 sucking the choke closed

 

[jacktheripper]

Run it without the air filter and see if it gets better. It could be plugged up, but I doubt it’s the actual air filter design. Only one I’ve really had trouble with is the 026 sucking the choke closed

Here’s what I did:


Here’s the video:
272xp mod #2

Seems to have shaved 2.5 seconds off. I am contemplating raising the uppers more. Blowdown is currently at 20 degrees. Maybe go up to 17? 16?

 

[Sloughfoot]

Here’s what I did:

View attachment 475439View attachment 475440
Here’s the video:
272xp mod #2

Seems to have shaved 2.5 seconds off. I am contemplating raising the uppers more. Blowdown is currently at 20 degrees. Maybe go up to 17? 16?

What's the tradeoff with lower blowdown? Peaky torque curve?

 

[jacktheripper]

What's the tradeoff with lower blowdown? Peaky torque curve?

I think it should bring some more torque in the cut. Any thoughts @Stump Shot @huskihl ?

 

[Sloughfoot]

I think it should bring some more torque in the cut. Any thoughts @Stump Shot @huskihl ?

How's it compare to your Mastermind 044?

 

[jacktheripper]

How's it compare to your Mastermind 044?

Mastermind was at least two seconds faster in the same wood. MOFO 440 hybrid was almost four seconds faster.

 

[Sloughfoot]

Mastermind was at least two seconds faster in the same wood. MOFO 440 hybrid was almost four seconds faster.

Iirc 102 22 78 is what he's said his target numbers are for 044s.

 

[jacktheripper]

Iirc 102 22 78 is what he's said his target numbers are for 044s.

044 is 50mmx36mm
272 is 52mmx34mm

I wonder how the bore/stroke ratio comes into play with blowdown.

My 266xp that I ported without machine work earlier in this thread had 16 degrees of blowdown, coming up from 20 degrees. That 4 degree difference made the saw run way better. It might just be my favorite saw to run because it just feels right. It runs like a ported saw no doubt.

So should the 2mm larger bore of the 272 affect port timing differently?

Interestingly, this machined and ported 272 that I put a lot of time into doing the right way doesn’t feel as hot as the 266 does. It also is running 20 degrees of blowdown. My gut tells me to raise the uppers.

 

[Sloughfoot]

044 is 50mmx36mm
272 is 52mmx34mm

I wonder how the bore/stroke ratio comes into play with blowdown.

My 266xp that I ported without machine work earlier in this thread had 16 degrees of blowdown, coming up from 20 degrees. That 4 degree difference made the saw run way better. It might just be my favorite saw to run because it just feels right. It runs like a ported saw no doubt.Y

So should the 2mm larger bore of the 272 affect port timing differently?

Interestingly, this machined and ported 272 that I put a lot of time into doing the right way doesn’t feel as hot as the 266 does. It also is running 20 degrees of blowdown. My gut tells me to raise the uppers.

Yeh, No expert but I'd think the shorter stroke would call for less blowdown. I believe popular opinion for an 044 is 20 blowdown minimum. 20-24 window. Going into the high teens might be a difference maker. Did you measure compression?

 

[jacktheripper]

Yeh, No expert but I'd think the shorter stroke would call for less blowdown. I believe popular opinion for an 044 is 20 blowdown minimum. 20-24 window. Going into the high teens might be a difference maker. Did you measure compression?

Didn’t measure compression, but it definitely feels stronger. I put a ring in it less than a year ago, and it honestly hasn’t been run enough to break in the ring since then. I have a feeling the comp will come up over then next 5-10 tanks.

 

[huskihl]

A couple more degrees of blow down usually makes it a little bit more forgiving, but won’t hold RPMs as well in a simple down cut. You can kinda make up for too high of an exhaust by leaving the transfers down a little bit. Kinda. But raising them up will definitely increase the RPMs it will hold in the cut. But again, transfer direction, exhaust port wall straightness (bubble versus hourglass shaped), it all comes into play

 

[jacktheripper]

A couple more degrees of blow down… won’t hold RPMs as well in a simple down cut.

This seems contradictory to this:

But raising them up will definitely increase the RPMs it will hold in the cut.

What do you mean @huskihl? Thanks for your replies!

 

[Sloughfoot]

This seems contradictory to this:


What do you mean @huskihl? Thanks for your replies!

Had to reread it a time or 5, myself. I believe what he's getting at is a higher blowdown number (lower transfer roof) won't cut at as high of an rpm as a lower blowdown number (higher transfer roof). Could be wrong. Blowdown speak makes my 3D dyslexia hurt.

 

[huskihl]

This seems contradictory to this:


What do you mean @huskihl? Thanks for your replies!

Not contradictory, just that I’m not relaying what I’m trying to say very well. Raising the transfers and raising the exhaust will both make the saw want to operate at a higher RPM. Less bd focuses the RPM range to a smaller, narrower, higher rpm point at which the saw will be happy in. Like the early 562. Stock they were about 103 I believe on the exhaust and only 10–11° of blow down. They would cut very fast at a narrow RPM range but didn’t like to be lugged down at all or they would fall off the pipe

 

[huskihl]

This seems contradictory to this:


What do you mean @huskihl? Thanks for your replies!

But to make certain we’re on the same page, blow down is the distance from when the exhaust opens to when the transfers open.
It gets confusing depending on the context. More blow down one time means leaving the transfers lower, and the next time it could mean raising the exhaust up. It’s probably not the greatest terminology when you’re trying to figure out timing numbers

 

[jacktheripper]

Not contradictory, just that I’m not relaying what I’m trying to say very well. Raising the transfers and raising the exhaust will both make the saw want to operate at a higher RPM. Less bd focuses the RPM range to a smaller, narrower, higher rpm point at which the saw will be happy in. Like the early 562. Stock they were about 103 I believe on the exhaust and only 10–11° of blow down. They would cut very fast at a narrow RPM range but didn’t like to be lugged down at all or they would fall off the pipe

That makes sense. It sounds like I may benefit from a couple less degrees of blowdown (raise my uppers a couple degrees) to gain rpm in the cut. It sounds like this could come at the expense of some lugging power (dogged in torque), but may cause the saw to run faster while self feeding in its power band.