Stock port timing numbers Husky 55 Air Injected?

[777funk]

I recently aquired a nice Husqvarna 55. It has 3/8 and a 20 inch bar and I can stall it fairly easy. I'm sure it would do better with a 16 325. But it also has an unknown aftermarket jug. Id like to check the port timing on it. Does anyone have a reference point for a stock cylinder? Muffler and timing are stock I believe. Would it pull the 3/8 better if it were ported?

 

[Duane(Pa)]

Check the squish too. You may need some thick solder lol!

 

[777funk]

Check the squish too. You may need some thick solder lol!

I have 062 solder. I checked a Poulan 42cc and even it was under that. Would the 55 be higher than the poulan?

 

[Duane(Pa)]

I have 062 solder. I checked a Poulan 42cc and even it was under that. Would the 55 be higher than the poulan?

Have to check. I wouldn’t be shocked to see .045-.050
If you don’t touch the .062, that will explain the struggle.

 

[old guy]

I have a 55 with 180 comp, I don't remember checking squish but it must be very low, like less than .020.

 

[777funk]

Check the squish too. You may need some thick solder lol!

Wow. It's more than 0.062" solder. Just brought it down to 46 thou. Going to shoot for 20.

 

[Duane(Pa)]

Wow. It's more than 0.062" solder. Just brought it down to 46 thou. Going to shoot for 20.

Good call. That will change port timing significantly (that’s all I know) Hopefully some experts can advise you how to address that…

 

[777funk]

OP here. Starting point for this cylinder was (approx by flywheel degrees):

Intake Open 62 BTDC
Intake Closed 72 ATDC
Intake Total 134 degrees

Exhaust Open 104 ATDC
Exhaust Closed 261 ATDC (or 99 BTDC)
Exhaust Total 157 degrees

TDC found by rotating crank until piston stopped upward travel, continuing to rotate until piston started downward travel, I counted TDC as the center of these two points. (no piston movement for 3-4 degrees).

EDIT: put a stop in there and found TDC more accurately. Numbers above are not accurate.

 

[777funk]

Squish was probably around 0.070". It has now been reduced to 0.015". Timing numbers will be much different. Haven't checked them yet. No idea what they should be for an ideal Open Port 55 saw.

 

[MAF143]

A few years ago I did a couple open port 55's for a neighbor. Both were stock OEM saws. Both measured the same.
stock timing was
exhaust: 103* for 154* duration
Intake: 70* for 140* duration
blowdown: 23*
Squish: .035"

I don't have a lathe so cutting base and squish band aren't an option for me.
I widened the exhaust and left timing alone to keep what torque it had. Ended up at 104*xxx
removed the base gasket
lowered the intake floor to 77* to get 154* duration (I may have raised the piston skirt on these, I don't remember)
blowdown remained at 23*xxx
Squish ended up at .025
gave 'em a 6* advance on the ignition timing

EDIT: I just flipped the page in my notebook (my notes are cryptic at best, I knew what I was talking about at that time). I didn't leave the exhaust port there. I ended up raising the exhaust to 101* for 158* duration and ended up with blowdown at 26*

That's all with OEM cylinders.

He was very happy with them until I finally talked him into getting a warmed up Jred 2166 that came up locally for a decent price... He turned into a CAD monster after that.

 

[777funk]

I ended up using the following numbers from blsnelling on arboristsite for this saw from a 2015 thread I believe. Haven't put it together, but it has to be better than it was with the china cylinder at 70 plus thou squish. I could stop 3/8" 20" chain easy in a cut. Hoping it will pull it a little better now. if not, I'll move it to 3/8 LP.

Back to the saw, it's now at under 20 thou squish. And the numbers... 104, 124, 78. I used a 1/4" upcut spiral carbide router bit (Whiteside brand) in a drill with sideways pressure conventional milling to hog out the exhaust a little wider. That thing works awesome. Easy to control (would not try it in a router) and takes off chips instead of dust. I didn't touch the intake port, but did take a little off the bottom of the piston skirt on the intake side to give it a little more intake. I also moved the transfers up a hair (less than they went down by removing squish) to reach 124.

 

[dangerousatom]

I had a 55 that I just sold in Nov to a friend, it had like 145-150 comp when I first got it used. It was the first saw I ever really fully worked over and hand ported. Deleted the gasket and solder tested the cylinder gap and it still was over 50k. Bench sanded it to just under 20k and tossed a pop-up in it with a new cabar ring and dang! 195 psi after 3tanks of gas. There seems to be a lot of room in that saw when it comes to squish, exhaust & intake levels. I don’t know how much I took out of ether side as I basically raised/lowered to the gap I thought safe. You can do a lot of widening it that thing too. It felt like 2x the saw after I was done screwing around with it. I learned a ton with it along with this forum and YouTube vids.

Edit: It also responded very well to a timing advance via an offset shim.