Stihl 026 porting

[James Sawyer]

It's good to have a starting point.

Success does not require professionalism, nor does using this forum. What does this matter even concern you?

Sounds like you kept repeating mistake on choosing competent people. That could lead to a profound disappointment. There are constructive ways to deal with it. For instance, discussing it with close ones can be very helpful. Arguing with strangers on Facebook or forums rarely provides long-term relief.

That's not true. You know, chainsaws are not eternal. They tend to break every 25 years or so.

Not true either.

Vesa keep in mind ported saw aren't for everyone, they burn more fuel, and they make more heat and need cooling down time to be reliable. Also, this the internet so don't believe everything you read. The porting number for a saw from a different displacement may not work on a small displacement saw. That small cylinder and getting in there to bevel the ports might be a challenge. I'm personally try avoiding moving my ports because I don't want chip the coating or the chrome. .010 to .012 is about 1 degree. and couple degrees can be a lot on saws. How much pressure and speed you have on the cutter and the direction you pull the cutter makes a difference. The type of cutters make a different some are grabby. If you do chamfer the ports, I suggest a diamond stone. Porting a cylinder the steady you can hold the cylinder and you're tooling the better. The 1st cylinder I did by hand (cylinder and tooling) it came out not too bad. I'm not saying porting is art, but they are skills involved and people use all kinds of tooling. The steady hand is the key. Get your numbers, mark your reference points... cylinder and piston. The exhaust if you are going open it mark those referance point on the piston so have a reference. Do not just go free hand beyond your reference marks because it looks better on the inside ports, a little can be the difference between a good running saw an not! The timing number are the point on porting. Clean everything piston, cylinder soap and hot water then clean again. Break cleaner to remove the oil before, soap and water. remember any chip or debris from the muffler and cylinder... you just lost all your work on the saw startup. Oh, use oil with your cutter it helps, but some people just cut without oil. I would suggest you change the seals and leak test when you done and tune... maybe run a little fat for the 1st 5 tanks. Also, keep in mind a small displace saw you open up the intake the crank case area chances and that piston only pulls so much vacuum. If the fuel has no pull it won't flow. Anyway, these are my suggestions. Thats a small cylinder so those cutters can remove a lot of material in a hurry with wrong pressure or movement.

 

[bwalker]

Vesa keep in mind ported saw aren't for everyone, they burn more fuel, and they make more heat and need cooling down time to be reliable. Also, this the internet so don't believe everything you read. The porting number for a saw from a different displacement may not work on a small displacement saw. That small cylinder and getting in there to bevel the ports might be a challenge. I'm personally try avoiding moving my ports because I don't want chip the coating or the chrome. .010 to .012 is about 1 degree. and couple degrees can be a lot on saws. How much pressure and speed you have on the cutter and the direction you pull the cutter makes a difference. The type of cutters make a different some are grabby. If you do chamfer the ports, I suggest a diamond stone. Porting a cylinder the steady you can hold the cylinder and you're tooling the better. The 1st cylinder I did by hand (cylinder and tooling) it came out not too bad. I'm not saying porting is art, but they are skills involved and people use all kinds of tooling. The steady hand is the key. Get your numbers, mark your reference points... cylinder and piston. The exhaust if you are going open it mark those referance point on the piston so have a reference. Do not just go free hand beyond your reference marks because it looks better on the inside ports, a little can be the difference between a good running saw an not! The timing number are the point on porting. Clean everything piston, cylinder soap and hot water then clean again. Break cleaner to remove the oil before, soap and water. remember any chip or debris from the muffler and cylinder... you just lost all your work on the saw startup. Oh, use oil with your cutter it helps, but some people just cut without oil. I would suggest you change the seals and leak test when you done and tune... maybe run a little fat for the 1st 5 tanks. Also, keep in mind a small displace saw you open up the intake the crank case area chances and that piston only pulls so much vacuum. If the fuel has no pull it won't flow. Anyway, these are my suggestions. Thats a small cylinder so those cutters can remove a lot of material in a hurry with wrong pressure or movement.

I've never once had a ported say run noticibly hitter than a stock one. I've also never let a saw cool down.

 

[Vesa Julin]

Vesa keep in mind ported saw aren't for everyone, they burn more fuel, and they make more heat and need cooling down time to be reliable. Also, this the internet so don't believe everything you read. The porting number for a saw from a different displacement may not work on a small displacement saw. That small cylinder and getting in there to bevel the ports might be a challenge. I'm personally try avoiding moving my ports because I don't want chip the coating or the chrome. .010 to .012 is about 1 degree. and couple degrees can be a lot on saws. How much pressure and speed you have on the cutter and the direction you pull the cutter makes a difference. The type of cutters make a different some are grabby. If you do chamfer the ports, I suggest a diamond stone. Porting a cylinder the steady you can hold the cylinder and you're tooling the better. The 1st cylinder I did by hand (cylinder and tooling) it came out not too bad. I'm not saying porting is art, but they are skills involved and people use all kinds of tooling. The steady hand is the key. Get your numbers, mark your reference points... cylinder and piston. The exhaust if you are going open it mark those referance point on the piston so have a reference. Do not just go free hand beyond your reference marks because it looks better on the inside ports, a little can be the difference between a good running saw an not! The timing number are the point on porting. Clean everything piston, cylinder soap and hot water then clean again. Break cleaner to remove the oil before, soap and water. remember any chip or debris from the muffler and cylinder... you just lost all your work on the saw startup. Oh, use oil with your cutter it helps, but some people just cut without oil. I would suggest you change the seals and leak test when you done and tune... maybe run a little fat for the 1st 5 tanks. Also, keep in mind a small displace saw you open up the intake the crank case area chances and that piston only pulls so much vacuum. If the fuel has no pull it won't flow. Anyway, these are my suggestions. Thats a small cylinder so those cutters can remove a lot of material in a hurry with wrong pressure or movement.

Good points. There has been time to plan and study. There's no really need to push the limits, so I plan to start cautiously and try things out. But first, I need to fix the squish. I think that with a bit of porting, modifying the exhaust, and changing the air cleaner, I can achieve just what I need. If not, there's always possibility to go bigger.

Due to legal issues, young people here favor 50cc two-stroke bikes. I started with one of those myself, so I became familiar with porting. Sometimes things got ruined and I had to start over. Fortunately, the financial damage was never significant. The parts were inexpensive.

 

[James Sawyer]

We

I've never once had a ported say run noticibly hitter than a stock one. I've also never let a saw cool down.

We'll I know that ported saw can run hotter and if a firewood cutter just run the heck out it... its going to get hot. You're burning more fuel to make that extra power, that saw going run leaner as it gets hot... just saying you might want to consider that unless you just don't care if the saw toasts.

 

[bwalker]

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We'll I know that ported saw can run hotter and if a firewood cutter just run the heck out it... its going to get hot. You're burning more fuel to make that extra power, that saw going run leaner as it gets hot... just saying you might want to consider that unless you just don't care if the saw toasts.

Might have cut a bit of firewood with a ported saw...

 

[Lionsfan]

If you were failure with it and knew what you were doing you wouldn't be asking for numbers. A guy that ports saws for a living would be a ****** to give those numbers out.
The 026/260 isn't a great unit for porting, but I only figured this out after having multiple competent people port one for me.
Aftermarket cylinders are trash, but it sounds like you had a lean condition that roached your first cylinder. Rather than fix it right you slapped a new cylinder on it again and as a result it's partially seized and has lost compression.

The guy who ports my saws has posted his numbers more than once for guys who are just starting out. He's helpful, and confident in his work but I certainly don't believe anyone who's dealt with him would call him a ******.

We

We'll I know that ported saw can run hotter and if a firewood cutter just run the heck out it... its going to get hot. You're burning more fuel to make that extra power, that saw going run leaner as it gets hot... just saying you might want to consider that unless you just don't care if the saw toasts.

If anything, mine have run cooler after being ported.

 

[bwalker]

The guy who ports my saws has posted his numbers more than once for guys who are just starting out. He's helpful, and confident in his work but I certainly don't believe anyone who's dealt with him would call him a ******.

If anything, mine have run cooler after being ported.

I have seen the guy I now use, who I think is also your guy when asked about a set of numbers reply something like "that's close" or that "will work Ok". I haven't seen him give an exact blue print for what he does. I woukd never expect him to, just like I woukd expect Coke or KFC to give me their recipes. It's just very rude to ask for such a thing and honestly it gets under my skin.
And yea if anything they do run cooler, I agree. Part of that is opening the muffler up.

 

[Lightning Performance]

We

We'll I know that ported saw can run hotter and if a firewood cutter just run the heck out it... its going to get hot. You're burning more fuel to make that extra power, that saw going run leaner as it gets hot... just saying you might want to consider that unless you just don't care if the saw toasts.

Burning more fuel cools the piston. I run WOT for up to 14 minutes on a ported 660 milling with 42" bat. Ran the 60 yesterday, just modified, flat out for ten minutes down this pld sugar maple. That cooling stuff down is for race days not work days.
Not really sure you could run it hotter or harder. They do it 95°F summer heat just fine. The 660 is now over 200 psi for sure. 68 missing off the base now.

 

[James Sawyer]

I have seen the guy I now use, who I think is also your guy when asked about a set of numbers reply something like "that's close" or that "will work Ok". I haven't seen him give an exact blue print for what he does. I woukd never expect him to, just like I woukd expect Coke or KFC to give me their recipes. It's just very rude to ask for such a thing and honestly it gets under my skin.
And yea if anything they do run cooler, I agree. Part of that is opening the muffler up.

I understand one guys numbers may not work for others, that guy isn't grinding for them so that's hard to say why they don't work. Setting up the timing wheel can be off a couple degrees from how that guy got his numbers. Also, if the ring isn't on the piston ... your exhaust time can be off depending on what you call 1st light. At TDC the piston and rod stroke have some play for the exact TDC, that is all experience which is hard to translate to the 1st timer. I find it easier to set the wheel to BDC, or use a height gauge which isn't prefect either because the plug port is at angle to the piston. A guy can always get numbers but to double verify you can place a loose ring above the piston and drive it to the number and pull the cylinder and check. The biggest problem how do you communicate confidence to someone that has no experience, you have confidence in your number and layout marks numbers to port well. Just my thoughts on porting certainly I'm no expert. I always question my setup because I don't do this every day and it only a saw here and there so certainly not expert. The thing about porting you can't add material back, but you can grind short try it... If you need more ... pull the cylinder and remove more material. Creep up on the numbers. Compression has nothing to do with crank case vacuum to pull fuel. You increase the intake or intake port size you have a larger volume/area to suck down, bring the exhaust port up you have less compression. The factory has to have numbers they can manufacture consistently and reliably too, for Mutiple users. Guy has to think they do know something about saw performance can I do better than them with tools I have in my toolbox? Every saw displacement is different I think when it comes to porting which is why I have questions when I port a saw.

 

[thompsoncustom]

You will not be running the OEM 026 air filter if you switch to a bigger carb.

Ya not something I've had time to play with to much but I can currently run it on my ms460/044 style carb but I fell like you could make it better than stock if you wanted to put in the time and still run a somewhat stock setup and I'm talking about the ms260 air filter not the 026 that one is a waste of time as it's even smaller. I'd have to take measurements but the ms361 carb might be a good option giving you a bigger venturi but still allowing you to use the choke flap inside the airfilter and not have to build your own setup to make the 044 carb choke work. You would have to remove the choke butterfly on the 361 carb and enlarge the hole and flap but I think it might be a easier option for some people looking for a bigger carb. Also the nylon mesh air filter flows more but still has a lot of wasted space which you could cut out and add more nylon for more flow.

I'm sure I'll play around with this at some point but to many irons in the fire right now.

 

[Lightning Performance]

I understand one guys numbers may not work for others, that guy isn't grinding for them so that's hard to say why they don't work. Setting up the timing wheel can be off a couple degrees from how that guy got his numbers. Also, if the ring isn't on the piston ... your exhaust time can be off depending on what you call 1st light. At TDC the piston and rod stroke have some play for the exact TDC, that is all experience which is hard to translate to the 1st timer. I find it easier to set the wheel to BDC, or use a height gauge which isn't prefect either because the plug port is at angle to the piston. A guy can always get numbers but to double verify you can place a loose ring above the piston and drive it to the number and pull the cylinder and check. The biggest problem how do you communicate confidence to someone that has no experience, you have confidence in your number and layout marks numbers to port well. Just my thoughts on porting certainly I'm no expert. I always question my setup because I don't do this every day and it only a saw here and there so certainly not expert. The thing about porting you can't add material back, but you can grind short try it... If you need more ... pull the cylinder and remove more material. Creep up on the numbers. Compression has nothing to do with crank case vacuum to pull fuel. You increase the intake or intake port size you have a larger volume/area to suck down, bring the exhaust port up you have less compression. The factory has to have numbers they can manufacture consistently and reliably too, for Mutiple users. Guy has to think they do know something about saw performance can I do better than them with tools I have in my toolbox? Every saw displacement is different I think when it comes to porting which is why I have questions when I port a saw.

You question your setup because your methods are not sound. Go read more about how you should be finding TDC. It is NOT a variable measurement. It is a precise number if done correctly. There are several methods to be completely accurate.

Many measure port chamfers not port openings. Depending on the size of said bevels or chamfors determines when the port starts working.

Timing numbers done on the acual chassis will vary from listed specs done by measuring port heights. Stroke and con rod length must be accommodated accordingly along with piston installed height.

Timing wheels don't lie people do. Numbers don't lie either.

Certain things need to overlap others should not. Think about that for the next decade. Just remember it is easier for most people to view a visual graph to map port time. The problem is most people don't understand simple geometry. Port relationships matter more than port time or duration of the duration.

See clear as mud, enjoy.

 

[Vesa Julin]

I adjusted the squish to 0.015 and then measured the ports. Exhaust opens at 96, the intake opens at 70, and the upper transfer opens at 123 (it was hard to see, but several repetitions gave the same reading). This is a good place to continue later. Meanwhile, I've been watching THE ISONHORSE videos. He seems to have thought it through.

How about the piston rings. There are two, but it seems that some use only the upper one. Which is the correct way for a ported saw?

 

[thompsoncustom]

Meanwhile, I've been watching THE ISONHORSE videos. He seems to have thought it through.

Stop right there and never watch any of his videos again that guy is terrible and anyone that knows anything about porting saws will tell you the same thing and pretty much anyone on any chainsaw forum(Not trying to be rude just helpful). Not saying he doesn't say some things that are accurate but most is what he says is garbage and misleading.

How did you go about adjusting squish? with the timing numbers you posted I assume you didn't cut the base of the cylinder. I would say run 2 piston rings unless you lower the cylinder enough that you get above 230psi for compression than I would remove the lower ring as compression north of 230 for this saw your just making more heat and starting to fight yourself a little so losing the lower ring will drop the compression and raise rpm's.

 

[Vesa Julin]

Stop right there and never watch any of his videos again that guy is terrible and anyone that knows anything about porting saws will tell you the same thing and pretty much anyone on any chainsaw forum(Not trying to be rude just helpful). Not saying he doesn't say some things that are accurate but most is what he says is garbage and misleading.

How did you go about adjust squish? with the timing numbers you posted I assume you didn't cut the base of the cylinder. I would say run 2 piston rings unless you lower the cylinder enough that you get above 230psi for compression than I would remove the lower ring as compression north of 230 for this saw your just making more heat and starting to fight yourself a little so losing the lower ring will drop the compression and raise rpm's.

Thanks for the heads up. I have already noticed that it's not wise to rely on just one source. Therefore, I follow other channels as well and have noticed that quite a few YouTubers speak contradictorily. It might be best to listen to the reasons and make decisions myself. It seems that chainsaws evoke strong emotions in some parts of the world. Here, it is just one tool among others. I have been in the forestry industry for decades and had never heard of chainsaw porting before this. Usually, a non-functioning saw is simply recycled or left forgotten in the garage.

This is a Chinese eBay cylinder, so the readings might not look like it, but I cut from the base of the cylinder.

 

[thompsoncustom]

lol ya some people get all worked up over brands and what not but it makes no difference to me as long as it works as it should and the quality is there. Indeed do your own research and learn as much as possible. For example the black 026/260 in my avatar is a mixture of stihl OEM parts along with china parts just need to use OEM where it counts like the cylinder/case.

Is the squish measurement with or without the base gasket? To make these cylinders really run you need to remove material from the band cutting the base isn't enough as you can see your still along ways from the 104 to 106 exhaust.

You should put on your OEM cylinder and compare the stock OEM timing numbers I bet even without cutting the base your stock cylinder exhaust numbers are better or about where your at now.

 

[Vesa Julin]

Currently, the measurements are without the base gasket. I'll probably use gasket sealant, but naturally, I don't want to glue the cylinder for every measurement. I just need to estimate a few thousandths. The OEM cylinder would also be usable. It just needs a new piston. Maybe, however, I'll practice first with the eBay cylinder. For now, the project can wait a bit while I gather more information and decide on the character I want for the saw. We've had a late winter return, and it's just too cold in the workshop.

 

[thompsoncustom]

Currently, the measurements are without the base gasket. I'll probably use gasket sealant, but naturally, I don't want to glue the cylinder for every measurement. I just need to estimate a few thousandths. The OEM cylinder would also be usable. It just needs a new piston. Maybe, however, I'll practice first with the eBay cylinder. For now, the project can wait a bit while I gather more information and decide on the character I want for the saw. We've had a late winter return, and it's just too cold in the workshop.

indeed no need to glue the cylinder down for measurement just bolt it down.

practicing on the ebay cylinder is a great idea when I'm trying new ideas or pushing the envelope I'll play with china cylinders as it doesn't hurt my fells to much if it grenades and I've blown up a few. the biggest problem is somethings can't be tested on them because you might not be able to achieve the same numbers because how the cylinder was cast.

 

[Vesa Julin]

I suppose this could be called a success. The exhaust port on the eBay cylinder was so far off target that timing it right was not realistically possible. So, I decided to practice porting and increase the torque on this one.

I widened the exhaust to the maximum and enlarged the channel along the muffler. I enlarged the lower ends of transfers and did not touch the downblow. I lowered the intake to 75°. I emptied the muffler and welded an outlet from a 20mm pipe.

The RPMs sound kind of low, but the torque definitely increased. A 20" bar sinks into spruce like never before. This encourages me to buy a new piston for the OEM cylinder and port it.

The cause of the starting problem was also discovered. A faulty contactor spring does not keep the port on air filter closed.