Porting advice Husqvarna 181/288 hybrid

[Will Kraemer]

When you say flipping the intake port, are you talking about making the floor of the intake slightly flatter? which I could achieve by squaring off the bottom corners of it.

 

[cus_deluxe]

When you say flipping the intake port, are you talking about making the floor of the intake slightly flatter? which I could achieve by squaring off the bottom corners of it.

yes

 

[cus_deluxe]

sides can be absolutely vertical, though youve widened the intake out far beyond where you can make the bottom of the intake anywhere near flat.

 

[Will Kraemer]

Done with class finals so I can get back to the fun stuff!

Squared up the intake some. I am just unsure on how much lower to bring those corners down. Right now the corners sit about and 1/8” higher than the lowest part of the floor. Am I able to go to 1/16”, or would that cause the rings to wear prematurely?

Sent from my iPhone using Tapatalk

 

[Yotaismygame]

That’s not bad at all. The rings don’t travel over the intake so the floor can be completely flat.

 

[Will Kraemer]

Didn’t even think about that. Guess I’ll do some more grinding on that then. Thanks


Sent from my iPhone using Tapatalk

 

[huskihl]

Slide the piston in right where the intake opens and mark the skirt so you can see how it lines up. Some pistons have the corners chamfered off. If you have it too tight in the corners, those chamfered areas can open first

 

[drf255]

I used to go big on the intakes, it was a mistake on a worksaw.

Guesstimate what’s around 10-20% bigger than your carb bore and make it around that big. Watch out for where the ring gaps are on the intake roof, they have to stay tucked at BDC.

You want the floor flat as mentioned. Too big and too square will ruin throttle response and wear the piston skirt faster. The intake is the thrust side for the piston on a saw.

What’s going on with your exhaust roof? Do I see chipped plating there?

Numbers look real good BTW.

 

[Will Kraemer]

I think what your talking about is on the roof of the exhaust chamfers. I haven’t touched those, that is how the chamfers came from the factory. All of the chamfers on the ports aren’t very consistent, I guess that’s what you get for non OEM cylinders.


Sent from my iPhone using Tapatalk

 

[Will Kraemer]

Got the floor of the intake flattened out and the sides squared up. There’s no radius on the piston and I left about .08-.09 on either side of the intake port to support the piston. Seems to be going well.

Sent from my iPhone using Tapatalk

 

[Yotaismygame]

You done yet?

 

[Will Kraemer]

Sorry to keep y’all waiting on the progress. But been out of town for a while. When I get back to work on it, I need to finish polishing, touch up chamfers, match muffler and intake block, and dual port the muffler.


Sent from my iPhone using Tapatalk

 

[Yotaismygame]

If you have this muffler you can simply flip the one deflector around and open it up. But like you see here it’s easy to add a port. Btw I just picked this saw up. Will be getting massaged lol

 

[Will Kraemer]

So finished up matching the exhaust and intake only to find a small crack in the intake block. So hopefully I’ll get the new one in a week.

One thing I noticed was interference with the screws on the bottom of the carb and case that causes the cylinder tone about 1/16” high from sitting flush. Is it fine to grind pretty deep Into the case right below the carb?

Also, on the faces of the intake block, it has some ridges that surround the impulse and the main air tract. In order to get the intake block to match up with the ported intake, it will require grinding past that ridge.
Am I able to sand that ridge flush with the face of the block and make a gasket to seal it?

While I wait for the intake block, I will Work on filing the flywheel key to advance the timing.

 

[Ronie]

So finished up matching the exhaust and intake only to find a small crack in the intake block. So hopefully I’ll get the new one in a week.

One thing I noticed was interference with the screws on the bottom of the carb and case that causes the cylinder tone about 1/16” high from sitting flush. Is it fine to grind pretty deep Into the case right below the carb?

Also, on the faces of the intake block, it has some ridges that surround the impulse and the main air tract. In order to get the intake block to match up with the ported intake, it will require grinding past that ridge.
Am I able to sand that ridge flush with the face of the block and make a gasket to seal it?

While I wait for the intake block, I will Work on filing the flywheel key to advance the timing.

On mine I had to grind a little under the carb to get it all lined up.

 

[Will Kraemer]

Copy. I feel that I might have to grind the screws and case down quite a bit to get it to fit.

But the timing advance is done so while I wait for the new intake block I’ll add the second muffler port.

-also I’m wondering if it would be wise to change the crank seals. What would be an indicator of that?

 

[Yotaismygame]

On mine I had to grind a little under the carb to get it all lined up.

Yes you’ll have to when lowering the jug that much.

Do a vacuum and pressure test to see if the seals are still good. I can go into detail about that later but there’s a lot of info about that on the web

 

[Will Kraemer]

Well finally got it all put together. Haven’t done the second exhaust port, but we’ll see how it runs tomorrow hopefully.

Sent from my iPhone using Tapatalk

 

[Yotaismygame]

I’ve been working on mine too. Should start porting soon

 

[Yotaismygame]

Get her running right then post a video.