Mods for milling? To port or not to port, that is the question!

[lumberjackchef]

Ok, I know this subject has been discussed before but I am rebuilding my 066 with a ported BB kit and just wanted to share what I am doing with this saw and post some of my findings for a reference for others pondering how to get more power from their milling saw, beyond just a muffler mod!

for anyone who is not familiar with what porting is all about check out this thread-

http://www.arboristsite.com/chainsaw/108900.htm​

History of my saw-

I ran this saw for three years with a woods ported-popup piston+muffler Mod. on a 48" alaskan type mill. It was already modified, but not mentioned in the listing, when I purchased it off of the bay for $575 back in 06. Bonus right? Well I didn't know it until I inspected the saw and noticed that there were several large pieces of the cylinder fins broken from the top of the jug. I called the seller and inquired as to why he had failed to mention this in the listing. He asked me if I had taken the jug off and had a look inside. I told him that I had not and he said that if I did I would understand why He had not replaced the p/c. After inspecting the inside I realized that he was correct, this thing had been ported by someone who really new what they were doing., not by a shadetree dremel hacker! And BTW the broken fins never caused a noticable problem on this cylinder. I still have it and it is still in usable condition!

I don't have the timing numbers but this is what had been done:

Exhaust widened, squared and rebeveled
Intake widenend and dropped to increase duration
transfers-bottom blended,ports angled back toward the intake, and raised slightly
Piston was milled and gasket was removed to minimize sqiush

This saw ran very well for many years of service and had i know that it had a rev limited coil it would probably still be running as it was purchased! My bad, You live and you learn.

Current Condition-

I have the saw back together and in the process of breaking in the new BB. Here's the kicker, the old 54mm modded p/c would've kicked the #@$% out of this stock 56mm p/c. It has not impressed me at all. I ported my little 3700 and it will run neck and neck with this BB in small wood right now. But It should be like night and day once I get the mods done.

After being spoiled by having accidentally purchased an already highly modfied 066. I cannot run a stock 066. It just feels very sluggish, high rpm, no torque, feels slow in big wood. So my answer is definitely to port! And yes I know you can get a bigger saw but that's not my point in this thread so bear with me!

Sorry for the novel but now to my questions:

1)How many serious millers are out there that are running ported saws on their mills?

2) How long of a service life should a properly modified milling saw have compared I hours to a stock p/c?


Reflections:

If the service life is shorter in hrs, then what are the costs vs. benefits to running modified saws on your mill. Such as-- Parts, cost of mods ( unless doing your own), quicker failure of other serviceable parts, more fuel consumption / Wider power band, more production for hrs spent , lower engine operating temperature, etc.


I hear a lot of opinions out there about these things, but I am planning on doing some comparisons before i get into the mods on this build so I will keep you posted as to what I find. Comparisons on Cutting times, fuel consumption, etc.

If you have done any similar mods to your milling saw and have comparisons with your please let us all know what you have found as well.

...and for those of you who have not had the experience of running a properly ported chainsaw for any purpose, i highly recommend that you make your way to the next GTG in your area and get your hands on one to run! If for know other reason it will tickle your cajones!

 

[mtngun]

l the old 54mm modded p/c would've kicked the #@$% out of this stock 56mm p/c. It has not impressed me at all.

WHAT BB kit ? They are not all the same. Some are junk, IMO. The current Bailey's BB kit is pretty darned good, with lots of torque for milling. Good fuel economy, too, which is important for milling so you can finish a long cut without pausing to refuel.

If you have the current Bailey's kit, I would set squish and call it good. If you have another kit, I'd scrap it and get the Bailey's kit.

In general, a milling saw needs lots of midrange power, from 6000 to 11,000 rpm. This is a different requirement than the cookie cutter saws over on the chainsaw forum. What you want is decent (160 - 180 psi) compression and moderate port timing.

Before you can decide to port any top end, you need to know what you got. What is the compression ? What is the squish ? What is the port timing ?

 

[BobL]

1)How many serious millers are out there that are running ported saws on their mills?

Relativey few - a poll was conducted a while back (see here)
One thing the poll did not ask is, who of the fraction that were running ported saws were serious millers.

2) How long of a service life should a properly modified milling saw have compared I hours to a stock p/c?

This is like asking how long is a properly modified piece of string. A properly modified saw could be properly modified to run for 10 minutes TOTAL, or 2000 hours.

If you who have not had the experience of running a properly ported chainsaw for any purpose, i highly recommend that you make your way to the next GTG in your area and get your hands on one to run! If for know other reason it will tickle your cajones!

Sure but unless money is no object it is backside tickling when a lot of effort and $ is put into modifying a saw and it dies

Mtngun has pretty well summed up the rest of my thoughts.

 

[lumberjackchef]

Before you can decide to port any top end, you need to know what you got. What is the compression ? What is the squish ? What is the port timing ?

Agreed.

I've heard that from snelling about the Bailey's kits being the best. I'm not sure who manufactured this particular one . But I will be putting a degree wheel on it and my old ported 54mm ported p/c tonight and do a little comparison. when you say moderate port timing what kind of numbers are you talking? do you know the numbers on your stock baileys BB kit?

 

[mtngun]

I'm not sure who manufactured this particular one .

In other words, it's not a current Bailey's BB kit.

when you say moderate port timing what kind of numbers are you talking?

If I had to pick a number out of thin air, I'd say 150 degrees intake duration, 160 degrees exhaust. Most 066/660 top ends have considerably more duration, but it seems to vary from jug to jug.

do you know the numbers on your stock baileys BB kit?

I'd have to dig up the old thread, but something in the neighborhood of 170 - 175 on both intake and exhaust. Far from ideal. The saving grace is a superior compression ratio.

I suggest checking to see if the piston freeports at TDC, as the old BB kits usually did.

 

[lumberjackchef]

Ok, you were correct it does free port slightly at TDC and according to what Brad has posted on other thread this is not the problem and he knows of some builders even taking these old kits as far as popups. We will leave that question for later. But here is what I found as far as numbers go...

I found the new BB kit numbers from this thread

http://www.arboristsite.com/chainsaw/161434.htm​

There was some talk about the old red light topend having a little more spunk than some of the others of the same bore so i pulled one of those out to put in the mix as well.

So here they are...............


New BB:

Exhaust Opens/Duration 96/168
Transfers Open/Duration 125/110
Intake Opens/Duration 86/172
Blow Down 29


My BB

Exhaust Opens/Duration 96/168
Transfers Open/Duration 122/116
Intake Opens/Duration 84/164
Blow Down 26


Red Light

Exhaust Opens/Duration 96/168
Transfers Open/Duration 120/120
Intake Opens/Duration 80/160
Blow Down 24


My Ported 066

Exhaust Opens/Duration 95/170
Transfers Opens/Duration 118/124
Intake Opens/Duration 82/164
Blow Down 23


So now I need to run a couple more tanks through the big barrel and do a test run with the mill on some slabs and start my little experiment.

 

[mtngun]

Ok, you were correct it does free port slightly at TDC and according to what Brad has posted on other thread this is not the problem

It's a problem. I ran one of those old kits for a while, it had a narrow powerband and never idled satisfactorily. I like and admire Brad, but he is a cookie-cutter, not a CSMer. We keep hoping to convert him, though.

Excellent timing data, I'll try to rep you for that. 066/660 jugs usually have ample duration, it's the compression ratio that is sometimes lacking.

Besides fixing the freeport problem, the current Bailey's kits have a significantly higher compression ratio and more blowdown. That gives it a wide, torquey power band despite the questionable intake and exhaust timing. Fuel consumption is the best of any 066 top end I have tried.

 

[gemniii]

Well I like to think I'm a serious miller, when I get a chance to mill. And I've a "snellerized" 660 (call it B) on which Brad also did a mild muf mod. However I also have a "stock" 660 (call it A) which I opened up the muffler a little and installed a DP cover.

When I opened up the stock muffler on A I noticed a little more power. When I put the DP muffler on it I noticed more power.

When I got B it seemed about the same as A, and I really can't tell that much difference in the cut between the two. But unfortunately my job has put me back on travel and between traveling and weather I haven't had much chance to mill recently.

(That should change after retirement.)

So

1)How many serious millers are out there that are running ported saws on their mills?

1 here

2) How long of a service life should a properly modified milling saw have compared I hours to a stock p/c?

I would expect to get about the same life out of my properly fueled (rich) B saw as my A saw, however I don't anticipate getting a third, totally stock 660 to compare it to.

 

[lumberjackchef]

Great input Gemniii. So the stock saw is the missing ingredient!

This is exactly what I'm after in my experiment, plus I want to see it in black and white.


I am going to use the stock top end as the control in the experiment that I am going to conduct. So the stock timing numbers will provide a base to work from. But I am also going to do a port map of the actual dimenions of the ports themselves, (before and after). This will give me a better idea of the differences in the powerband that the mods actually effect under a serious load, such as in milling, rather than how fast can I cut a cookie.

Out of curiosity do you know the timing numbers after brad snellerized your milling saw, or the port widths?

 

[Mswt]

I run a solo 694, which I just had snellerized for milling. I'm no expert on these little 2 strokes, but I can tell you that if I EVER get another saw for milling, I'm drop shipping it from the dealer straight to brad.

I milled some with un modded saw, and milled today again with the modded one. No comparison, as I mill for a living, and even if I burn the saw up sooner, it'll more than pay for itself with extra lumber milled, and less time on my back pushing it around.

I do large and small stuff, today I averaged 3:41 per cut on walnut and maple for 28" wide x 42" long. I have a big oak to do tomorrow, and will post comparison times.

The snellerized saw also sounds like a Beast, and let's everyone know what I'm up to that day....

 

[mtngun]

today I averaged 3:41 per cut on walnut and maple for 28" wide x 42" long. I have a big oak to do tomorrow, and will post comparison times.

= 0.19 inch/sec. Thanks for the speed data, keep it coming.

 

[Mswt]

To compare, my electric 3PH woodmizer will feed 6.5 inches per second through 8" wide red oak, and 2 inches per second on 16" wide red oak.


Chainsaw way slower, but I get much more per BF for live edge wide material.

I'll post more data tomorrow thru some 31" water oak w/chainsaw

 

[lumberjackchef]

I run a solo 694, which I just had snellerized for milling.


I do large and small stuff, today I averaged 3:41 per cut on walnut and maple for 28" wide x 42" long. I have a big oak to do tomorrow, and will post comparison times.

Out of Curiosity:

How big of a mill are you running your 694 on?

Do you know anything specific about the mods that were done to your saw?

 

[Mswt]

As far as mods go, you'll have to ask Brad Snelling. I sent it to him, and received back a Frankensaw......its great.

I run a 50" or 60" bar, but won't push the saw hard with the 60".

When I burn up the Solo, I'm dropping a Stihl 880 on Brad's doorstep with a box of cookies and a check.....hope he's amiable to it.

 

[hamish]

= 0.19 inch/sec. Thanks for the speed data, keep it coming.

Dan,
I sure hope you are keeping track of all these numbers and are going to post them in your thesis!

Jeremy