Chainsaw Porting Theory

[Stihlbro]

Absolutely, unless you are cutting at high elevations. Compression increase is a power adder. Too much compression can work against you in a work saw. Work saw I'm classifying a saw saw that runs all day. Not the one truck load firewood cutters. Not your 3 minute YouTube videos.

I'm not saying it's not done, or I am right. I am speaking of my experiences from my uses. The closer I get to 200lbs of cranking compression the more I find tunes change with saw getting to operating temperature. Cold saw it so rich it won't rev up till it gets to temperature.

Saw with closer to 175/185 seem to perform better from start to finish. Make sense?

Stock saws once tuned in, have you ever had to retune once dialed in in same cutting conditions?

 

[jmssaws]

I cut timber with a mild ported 215lb 395xp mainly because I shut off between trees to hear the skidder, I grow tired of starting and putting pull rope in a big compression saw.

On a side note, I worked my 240lb red light 066 55 hrs one week which might be a few hours a day actual run time,started the week with a new pull rope I got from DD and never had to replace it,probably started it over 100 times.

 

[Stihlbro]

A worksaw is a broad title,I think a worksaw is what you take to work,simple as that.
Will a high compression saw last forever cutting timber? No but neither will a stock one,I worked 6 days falling with a 066 that's 240lb of compression and I didn't think it would last but it did just fine.

I look at it like this, if your worried about how long your saw is going to last maybe you should leave it stock.

I haven't seen parasitic yet but I've only been to 240,maybe Scott has.

So have you tried less and found it starts easier? Does the carb settings never change. You are falling timber, take the same saw and rather than drop 30 trees, make 30 bucking cuts back to back. Same results?

 

[MustangMike]

I think this problem (excess compression) would be very rare unless you are at high elevation or compression is north of 220 lbs.

I know in cars, compression is usually one of the few FREE LUNCHES, in that it generally both improves power and economy. I would imagine that it would also usually add to the efficiency of a saw, as it can produce more energy from the same fuel.

 

[jmssaws]

My 064 is 220lb and will out cut my 66 with a 24" but with a 36" my 66 will clobber it.

If it takes 30 back to back cuts to slow it down in doubt I'll ever notice it,I'm not arguing I'm just thinking real world cutting.

I've built 100's of 200lb "worksaws" and they cut great but nowhere close to one with more compression. I'm also talking about 066's too,other saws I'm sure are different.

 

[jmssaws]

I wouldn't notice a tunability problem cause I tune them everytime I use one,just a habit.

 

[jmssaws]

I think this problem (excess compression) would be very rare unless you are at high elevation or compression is north of 220 lbs.

I know in cars, compression is usually one of the few FREE LUNCHES, in that it generally both improves power and economy. I would imagine that it would also usually add to the efficiency of a saw, as it can produce more energy from the same fuel.

I have only found that more compression means more power, but I'm sure at some point it would go the other way.
I have only seen one saw that was detonating and it was stock.

They say compression is cheap but actually it's the most expensive part,widening a port is cheap.

 

[Stihlbro]

My point is going for the most compression is not always the answer. The post I see, it's appears the more compression you make the more power you make. While that maybe true, there are other variables to consider. One being we all agree how you modify a saw is determined by how you use them. It appears to me that if you aren't making the most compression, you aren't building the saw. I disagree with that theory.

 

[jmssaws]

Compression isnt the answer but it's part of it.

I take a saw and get all I can from the factory parts,there not for everyone but that's how I like it,I don't want to build a "worksaw" anymore.

On a 066 the more the better but as I said before not all saws work that way.

I'm building dd hybrid right now and it won't have that much simply because I won't need it,it is a short bar saw so 210 will be fine

 

[jmssaws]

Million ways to screw this goat,ain't none of them wrong.

 

[Keith Gandy]

I know what Ive found out in a worksaw that I dont like. One that screams and cuts fast but the minute u pulled on the rear handle it gives up

 

[jmssaws]

I know what Ive found out in a worksaw that I dont like. One that screams and cuts fast but the minute u pulled on the rear handle it gives up

I don't like that either.
I like one that's fast with a short bar and a long one.

I like a aggressive chain and it takes a certain kind of saw to run one.

 

[Keith Gandy]

I don't like that either.
I like one that's fast with a short bar and a long one.

I like a aggressive chain and it takes a certain kind of saw to run one.

I built a hybrid that was fast but not the torque I like. Built a 460 right behind it with both rpm and torque that was awesome! I sold that 460 to a fellow in Florida that has a tree service that loved it!! Lol! He ask if I had anymore like it for sale

 

[Mastermind]

I've seen the tune issue that Joey is talking about. But......only in a few saws. The worst one is my Poulan 3750. Tune it perfect....then make a dozen cuts. It's screaming lean. Retune, and it's good to go......till it cools off. Then it's so fat it will hardly run. I was seeing that to some extent in the MS461 too. After I started drilling the main jet, that issue went away.

 

[jmssaws]

I don't like a hybrid much,I'd rather have the 44 or the 460.

 

[jmssaws]

I've seen the tune issue that Joey is talking about. But......only in a few saws. The worst one is my Poulan 3750. Tune it perfect....then make a dozen cuts. It's screaming lean. Retune, and it's good to go......till it cools off. Then it's so fat it will hardly run. I was seeing that to some extent in the MS461 too. After I started drilling the main jet, that issue went away.

I had that problem with a few wj69 carbs.

The way I tune a saw it will be cold natured,most would fatten it up when they started it.

 

[Keith Gandy]

I had that problem with a few wj69 carbs.

The way I tune a saw it will be cold natured,most would fatten it up when they started it.

I believe u said just off lean on the l then set the h and then back to the l for a final adjustment?

 

[jmssaws]

I believe u said just off lean on the l then set the h and then back to the l for a final adjustment?

That's how I tune one,haven't fried one yet. Lol

Lot of times my low will be less than a turn and my high will be over a turn,not much either way though,maybe a 1/8 of a turn and lean cold.

 

[Keith Gandy]

That's how I tune one,haven't fried one yet. Lol

Lot of times my low will be less than a turn and my high will be over a turn,not much either way though,maybe a 1/8 of a turn and lean cold.

Have u ever followed the tuning in the Stihl service manual? After several up and downs on rpm between the idle and the l the final idle is set with the l

 

[jmssaws]

I set the la to just touching and rarely have to mess with it.

I figure a saw tunes were it tunes,don't matter how you get there it should be the same.

For max power a saw should be tuned every time you use it,any change in temperature will change a tune. Airfilter restriction will change it.