Porting advice Husqvarna 181/288 hybrid

[Will Kraemer]

Hey yall,
Been cruising around this forum for a while but finally making a post.

I've got a husky 181se that runs great but I wanted to try my hand at porting. So that I didn't ruin the OEM jug, I bought a Hyway 288 Piston/jug kit and a meteor piston because it is slightly wider (only .030" to .050" if I remember correctly). I've done quite a bit of reading up on porting numbers for this saw and how to port and due to working in a machine shop, I feel that I'm fully capable of it. The porting numbers I currently have are as follows.

Hwy Jug and Meteor Piston with .003" base gasket
Squish @.020"
Ex 168...96atdc
Tr 130...115atdc
In 140...70btdc
BD 19

Hwy Jug and Hwy Piston with .003" base gasket
Squish @.028"
Ex 164...98atdc
Tr 126...117atdc
In 140...70btdc
BD 19

The numbers that scarr posted up somewhere was 99-118-79

In addition, the Hwy piston weighs .5 oz less than the Meteor. about 15-20% lighter.

Would you guys suggest Using the Hwy piston because it gets me close to scarr's porting numbers and less weight even though I wouldn't be able to go as wide with the exhaust port? I was also thinking about lowering the floor of the intake to increase the duration.

Thanks for the help,
-Will

 

[Yotaismygame]

I built one per rattlers advice and it was 100/120/80. Beast of a saw. Think comp was around 190. Used a hwy jug and meteor piston. Took .050 off the band and set squish to .020

 

[Yotaismygame]

I would have someone do some machine work on the jug. 70-80 with no machine work will be a huge intake. Timing advance as well. 98-99 exhaust with 20 degrees of blowdown sounds nice to me
https://youtu.be/m6PY6_kD_RQ

 

[Will Kraemer]

copy, If i bore the squish band .050" on a lathe and machine the base down to get .020", do you think that will get the exhaust to 100? Also, cause I can't lower the roof of the transfer, I think im stuck at 19 degrees of blowdown. is that the correct thinking?
And do you think the .5oz lighter hwy piston would be advantageous?

 

[Yotaismygame]

.050 off the band should put the exhaust around 5-8 degrees lower. So you’ll have to bring it back up. You’ll still need to grind the intake down a few degrees. Transfers will move down as well. You could do a pop up if you wanted. In that case the exhaust and transfers will stay the same. 055-060 might be better off the band. Get the intake really close to what you want it.

 

[Yotaismygame]

You want to machine the cylinder in a way that will put your intake at or near where you want it. The exhaust and transfers will lower which allows you to put them where you want it. I dont think a slight difference in weight will matter. Clean the casting lines off the meteor piston and it’ll probably be the same. With the Meteor piston though you’ll retain more compression. If it’s at 96 now it won’t be terribly low after the machine work which will net more compression.

 

[Yotaismygame]

Looks like I deleted the pics off my phone but tomorrow I can post some of the porting. The intake can take a lot of grinding. They might be on this forum, I know I posted about the saw somewhere. Let me check if I made notes about my timing numbers.

I did write it down. stock with hwy cyl and meteor piston was 98/117/69. I ended up at 99.5/120/79.5. Took 050 off the band and 060 off the base for a 020 squish. So the original squish was 030.

After machine work the numbers were 104/124.5/74

 

[Will Kraemer]

Thanks for all your info. I read your thread on the 288 but if you were to post some pictures that would be much appreciated. Just a few questions.
-Roughly how many thousandths of machining is equal to 1 degree?
-what do you run for a base gasket if you run one?
-how much advancement in timing would I need? Not sure Ill do it though because from what I've researched it can be a headache

also I don't have any small right angle dremels so I dont think i would be able to work on the transfers too much. I might just have to play with some numbers to get the exhaust where I want it so I don't have a ton of blowdown. or just buy a right angle dremel

 

[drf255]

-Roughly how many thousandths of machining is equal to 1 degree?
Try this free software. Every saw will be different.

http://www.torqsoft.net/piston-position.html

-also I don't have any small right angle dremels so I dont think i would be able to work on the transfers too much. I might just have to play with some numbers to get the exhaust where I want it so I don't have a ton of blowdown. or just buy a right angle dremel

A dremel 90* attachment will not fit in a cylinder head, at least not a chainsaw one. If you can’t get a true right angle tool, you can try a dremel with stacked cutoff wheels. It can work fairly well.

I don’t understand your original numbers. Looks like the meteor has a .008 higher crown, so it should result in a higher ex roof number (physically lower-less duration).

I’d use the meteor over the Hyway personally. The only lighter slug I’d use above a meteor would be oem. 14 grams is a lot more weight. That’s quite surprising.

 

[Yotaismygame]

Yes every saw will be different when machining. If you don’t have a right hand piece you can use a sphere burr. I did it that way before I got right hander. Worked fine. Can also use a cut off wheel. Base gasket you can use just about anything. Personally I use thin cardboard coated in copper spray if I need a gasket and don’t already have one. A single hole punch works well for the cylinder bolt locations.

 

[Yotaismygame]

Well looks like I didnt take many pics.

 

[Yotaismygame]

-how much advancement in timing would I need? Not sure Ill do it though because from what I've researched it can be a headache

Timing advance is easy. Just pull the flywheel key, file off about a third of it, put it back on, lock up the saw, rotate the flywheel counter clock wise, hold it in that position and hit it with your impact driver. Advancing the timing made a big difference for the saw I built.

Here's a pic how to hold the key when filing.

 

[Will Kraemer]

Awesome, thats a big help right there. Hopefully Ill be able to start doing some machining soon. One thing I noticed with my saw, that the highest it wanted to turn when it was a 181 was 11,400 and that was with the high all the way turned it. I believe its supposed to be up at 12.5k. I cleaned and put a carb kit in it but no change. Any ideas?

 

[Yotaismygame]

Hmm I dunno

 

[Will Kraemer]

Okay, well I start doing some machining and see how it all goes. Once again thanks for all the great info.

 

[Ronie]

Hey yall,
Been cruising around this forum for a while but finally making a post.

I've got a husky 181se that runs great but I wanted to try my hand at porting. So that I didn't ruin the OEM jug, I bought a Hyway 288 Piston/jug kit and a meteor piston because it is slightly wider (only .030" to .050" if I remember correctly). I've done quite a bit of reading up on porting numbers for this saw and how to port and due to working in a machine shop, I feel that I'm fully capable of it. The porting numbers I currently have are as follows.

Hwy Jug and Meteor Piston with .003" base gasket
Squish @.020"
Ex 168...96atdc
Tr 130...115atdc
In 140...70btdc
BD 19

Hwy Jug and Hwy Piston with .003" base gasket
Squish @.028"
Ex 164...98atdc
Tr 126...117atdc
In 140...70btdc
BD 19

The numbers that scarr posted up somewhere was 99-118-79

In addition, the Hwy piston weighs .5 oz less than the Meteor. about 15-20% lighter.

Would you guys suggest Using the Hwy piston because it gets me close to scarr's porting numbers and less weight even though I wouldn't be able to go as wide with the exhaust port? I was also thinking about lowering the floor of the intake to increase the duration.

Thanks for the help,
-Will

Welcome to the forum. On the one I did the numbers are pretty close to the one yotalsmygame did. My final numbers were, EX 100, IN 78, TR 120, squish 20 and I used a Hyway cylinder with a Meteor piston with a pop up. The numbers on the Hyway cylinder were a little different the the ones you got. The numbers I got were, EX 100, IN 70,
Tr 120 and the Squish was .030 without the base gasket. After cutting the base the flywheel was catching on the raised Hyway letters so I ground them down a bit. I also had to grind the case down below the carb. I'm not sure what the final wot rpm ended up being but it pulls a 30" bar in oak very well.

 

[John Stryker]

Awesome, thats a big help right there. Hopefully Ill be able to start doing some machining soon. One thing I noticed with my saw, that the highest it wanted to turn when it was a 181 was 11,400 and that was with the high all the way turned it. I believe its supposed to be up at 12.5k. I cleaned and put a carb kit in it but no change. Any ideas?

It might be a governed carb, and best tuned in the wood. Some people used to plug the governor by putting welch plug under the brass governor screw.

 

[Yotaismygame]

After cutting the base the flywheel was catching on the raised Hyway letters so I ground them down a bit. I also had to grind the case down below the carb.

I forgot about that. I had to do the same thing. Ended up grinding the letters completely off. on all 2-series huskies when lowering the jug the case will interfere with the carb. Ronie how big of a popup will the 288 piston allow you to make?

 

[Ronie]

I forgot about that. I had to do the same thing. Ended up grinding the letters completely off. on all 2-series huskies when lowering the jug the case will interfere with the carb. Ronie how big of a popup will the 288 piston allow you to make?

The one I cut was a little over .040. I'm not sure what the max would be. I wouldn't go any higher than that because the space between the ring and the top of the piston was getting kinda thin.

 

[Yotaismygame]

The one I cut was a little over .040. I'm not sure what the max would be. i would go any higer than that because the space between the ring and the top of the piston was getting kinda thin.

General rule of thumb is .1 above the ring. I was wondering how much space above that there is. Some pistons are only a total of .120 above the ring and others another .025.

OP I wonder if you could do both a popup and a band cut to save you from having to grind as much. If you you took .025 off the band and .025 pop up that would lower the exhaust and transfers down some but not a lot. Could end up with the exhaust around 99. Intake should land around 75 or so.