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

[MG porting]

Ok, my wife was out of town and I had time, so I ported my older 266 last night. It had the SE Mahle cylinder on it, labeled 50ZN11. I had an extra XP cylinder (50ZN13), so I decided to do that one.

Without base gasket, the numbers for the XP cylinder were:
Exhaust: 106
Uppers: 122
Intake: 70
Squish: .017"

I took down the ridges on the lower transfers and smoothed them out, being careful not to go deep towards the case. I removed some material inside the transfers behind the "bridge" to skinny them up as well.

Raised exhaust roof slightly to 102, really widened it up and funnelled it outwards. Exhaust roof was pretty flat from the factory, so I followed the factory contour. Polished everything up very nicely afterwards with aluminum oxide stone, then emery paper in a mandrel, then polishing compound and a felt wheel. Port matched muffler and gasket. Muffler was already modded.

Lowered intake to 78, widened, and cleaned up. Left it rough.

Went over edges with diamond ball, and then ball honed both directions.

Advanced timing 0.025" off the key.

Now it's sitting at:
Exhaust: 102
Uppers: 122
Intake: 78
Squish: .017"

I heat cycled it a couple of times, and then put it in the wood this morning. Pulled a 25" full comp with low rakers in some 20" green pine with way more power than before. Throttle response is way better. Tunes at WOT @13.2k. Holds 9.5k in the cut. Sounds great.

I'm happy. I used the full-circle piston that was in it, but I think I will tear it down and replace it with the windowed Meteor piston sometime in the near future. I'll share some pics then.

I think I will use this recipe for the 266 build that I am working on in the other thread.

I would leave the full circle piston in it but that's just me glad it worked out for you tho now you'll be finding saw to port just because

 

[mainer_in_ak]

Dang, nice work! You chose the right saw to port. The older dual port 67 cc saws are dirt cheap, and when woods ported at home, slap all of the current 60 cc saws silly. Parts are cheap and readily available.

I too started porting on the older 67 cc saws, and they sing a sweet song! They out-cut my stock jonsered 2172 and the neighbors stock stihl 044.

The 67 cc saws were 1/4 the price of my more modern 70 cc saws. Old, cheap woods ported 67 cc saws actually resulted in me quitting 40-50 cc saws. Gave em all away.

Never heavy in weight, and ideal for everyday cutting and most typical wood. Most smiles per dollar.

 

[mainer_in_ak]

Ok, my wife was out of town and I had time, so I ported my older 266 last night. It had the SE Mahle cylinder on it, labeled 50ZN11. I had an extra XP cylinder (50ZN13), so I decided to do that one.

Without base gasket, the numbers for the XP cylinder were:
Exhaust: 106
Uppers: 122
Intake: 70
Squish: .017"

I took down the ridges on the lower transfers and smoothed them out, being careful not to go deep towards the case. I removed some material inside the transfers behind the "bridge" to skinny them up as well.

Raised exhaust roof slightly to 102, really widened it up and funnelled it outwards. Exhaust roof was pretty flat from the factory, so I followed the factory contour. Polished everything up very nicely afterwards

Advanced timing 0.025" off the key.

Now it's sitting at:
Exhaust: 102
Uppers: 122
Intake: 78
Squish: .017"

Pulled a 25" full comp with low rakers in some 20" green pine with way more power than before. Throttle response is way better. Tunes at WOT @13.2k. Holds 9.5k in the cut. Sounds great.

9500 rpms in pine is a bit slow. Check the compression, that squish is a bit tight and might be fighting yah.

Pull the cylinder and raise the exuahst roof a couple more degrees. Should gain some rpms in the cut.

 

[huskihl]

9500 rpms in pine is a bit slow. Check the compression, that squish is a bit tight and might be fighting yah.

Pull the cylinder and raise the exuahst roof a couple more degrees. Should gain some rpms in the cut.

It needs the transfers raised 4° in order to get those RPMs back.

 

[jacktheripper]

It needs the transfers raised 4° in order to get those RPMs back.

Stacking cutting disks OK?

 

[jacktheripper]

I tuned it a bit leaner, still 4 stroking, holding more like 10.5k while self feeding low rakers now.

 

[Woodwackr]

I have a bunch of cleaned 266 carcasses if you need more, lol

 

[huskihl]

Stacking cutting disks OK?

I think everybody that has ever ported a saw has done it once or twice. I have cut the line I wanted and then smoothed it out with a round ball in a straight hand piece. Just be careful of the plating next to the port

 

[MG porting]

9500 rpms in pine is a bit slow. Check the compression, that squish is a bit tight and might be fighting yah.

Pull the cylinder and raise the exuahst roof a couple more degrees. Should gain some rpms in the cut.

If he raises the exhaust port it will loose torque like huskihl said raise the upper transfers.

 

[mainer_in_ak]

I have a 100 degree exuahst roof in my 67 cc saw, and have no issues with torque. 160 lbs of compression, 11,000 rpms in the cut 18 inch spruce. 13,500 rpms out of the cut. Slight 4 stroking when you lift the saw off the wood.

 

[jacktheripper]

What is the ideal blow down for these? Sounds like Kevin is saying 16 degrees is good?

 

[mainer_in_ak]

Identical bore and stroke to yer husq, dual port as well:

Joe stated 101 intake, 123 on transfers. Out of the cut Joe stated it's tuned at 13,600 rpms:

Thread 'Echo 6700 build'

Sep 9, 2016

Clean saw. Really similar to the 670 except Air filter, Chain brake, cover, front tensioner, and color. are the main visible ques.



Small ex port, but look at the dropped floor...



This one will clean up real nice...

• Red97
• Replies: 104
• Forum: Chainsaws

• 

 

[mainer_in_ak]

On mine:
100 degrees on the exuahst roof, 122 on the transfers.
The saw has been doing 16 ft-18 ft long milling rips for almost 3 years.

 

[MG porting]

I have a 100 degree exuahst roof in my 67 cc saw, and have no issues with torque. 160 lbs of compression, 11,000 rpms in the cut 18 inch spruce. 13,500 rpms out of the cut. Slight 4 stroking when you lift the saw off the wood.

Put a big bar on it and see how it does.

 

[Canadian farm boy]

Port timing is only 1 piece of the porting puzzle.
Port shape, size, aim, finish, bore, stroke, compression and more all come into play with a ported saw and what the intended use of the saw will be.
Don’t over think the numbers as being the end all be all.

 

[farminkarman]

What is the ideal blow down for these? Sounds like Kevin is saying 16 degrees is good?

102/118 should run real nice on that saw.

 

[jacktheripper]

Well I did the transfers today. Just finished it up and it's idling right now. Throttle response is way snappier! Here's some photos. Damn, the grinding looks way worse in photos! I used a ring to find 118, drew a line, and followed it with the stacked cutoff wheels. This method takes a long time, as the wheels are very inefficient at cutting.

 

[jacktheripper]

So, current (and maybe final?) numbers for this build are: 102, 118, 78. Very eager to get this into some wood with a tach tomorrow. I just placed an order for the windowed Meteor 268 Piston. Should up the speed even more, I hope.

 

[drf256]

Port timing is only 1 piece of the porting puzzle.
Port shape, size, aim, finish, bore, stroke, compression and more all come into play with a ported saw and what the intended use of the saw will be.
Don’t over think the numbers as being the end all be all.

Bingo

What percent Tariff will you be charging Mikey?

 

[drf256]

So, current (and maybe final?) numbers for this build are: 102, 118, 78. Very eager to get this into some wood with a tach tomorrow. I just placed an order for the windowed Meteor 268 Piston. Should up the speed even more, I hope.

I’m a “bit” of a stranger to the model. What’s the current slug look like?

Like Mike CFB said, the numbers are only part of the puzzle. You have to physically look at what’s going on as well. How much of the lowers does the piston cover after the intake floor closes? Where will the crank weights be at that time? What’s the case/displacement ratio?

There’s a pretty good chance that the windowed slug is going to increase case volume and decrease crank compression pressure. This will make the saw a slug to recover when it’s dawged down in the cut.

A lot of the older husky’s have assymetric uppers from the factory. Were yours even?

Your port work looks nice. Exhaust roof symmetry is sometimes easier to check with a piston in the bore. The only thing I don’t love is how big your uppers look.