The OH 26 Thread

Careful ,it may turn into a hotsaw

 

Did you look into your 026 to see what rim you have ?

 

It's at home ,i am stuck here late tonight ,maybe in the am i will snap a pic

 

Hey, your not running that chain..........it just landed in Illinois.

 

You want sexy 026's....have a look see. There's two 026's and a 260 in this box. I'm a pretty slow starter though and have just pulled jugs from two of them. Have a good 026 jug and piston, and the 260 jug cleaned up with Randy's emory cloth method, but the piston was fried. I'm hoping to piece together one runner, and get another runner for the least investment possible. I'm into the whole box for $10.00 so far.......Oh, and the box came with one bar and chain also.

 

This is yours with more work. LOL

 

Ryan, I was just saying what I've heard others say about the picco vs 3/8s rims. I wanted to see for myself, but I don't have a picco chain anywhere here.

 

I feel ya dawg , it looks like it may work..if i break a chain or somethin hopefully it doesnt smack me in muh chops .. i wouldnt be the first casualty of science

 

That's the spirit.

Carry on.

 

What set up was in your 026 vid?


Also what bar chain combos are people running on there ported 026's?

 

I want one!

 

You should copy this and send it to Mr. Piltz

If people are running picco on saws with large spline drums how are they doing it ? , stihl doesnt have a rim available and i called baileys and they cant source me one either , whats the trick ?

 

3/8 - 7 sprocket - pico chain ,shop lights were not warmed up yet so pic's are not too great

 

Thanks brian

 

Aren't the star/spur sprockets supposed to be good for different types of chain ?

 

Madsen's Shop & Supply Inc.

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Pro Saw Sprocket Systems

There are two main types of drive sprockets used on chainsaws. One is the "spur" style (marked A in the image) and the other, the floating sprocket system (marked B).

The floating style is the best drive system for pro saws for several reasons:

• With a floating sprocket system, the rim sprocket aligns perfectly with the groove in the bar. It self-aligns by "floating" on a splined hub.
• Spur sprockets damage the chain's drive links when the chain derails. A floating sprocket system usually does not. On a floating sprocket system, a derailed chain usually drops into the space next to the rim sprocket. There, the shallow splines don't cause the kind of damage a spur sprocket will.
• Floating sprocket systems don't cost much more than a spur sprocket. A significant economical advantage occurs when the sprocket wears or breaks. On a floating sprocket system, the rim sprocket is a separate part that is inexpensive and easily replaced. On saws with internal clutches, this is also very convenient. Sprockets are held on by an "E"clip and washer (marked C). This makes them easy to change in the field with minimal tools.

Sprocket Size & Gearing

The pitch of your sprocket, the pitch of your saw chain, and the pitch of your bar tip must all match. On most pro saws this will usually be: .325", 3/8", or .404". When replacing a sprocket, it is also important to know the amount of "teeth." For example, on a 3/8" pitch sprocket, both 3/8" X 7 and 3/8" X 8 sprockets are common.

The amount of teeth your sprocket has affects the "gearing" of your saw. Basically, smaller sprockets (seven tooth) give your saw the most cutting power. Larger sprockets (eight tooth) will produce the most chain speed.

Your chain's pitch also affects the diameter of its sprocket. A 3/8" X 8 sprocket is very close to the diameter of a .404" X 7 sprocket. This occurs because the 3/8" is a smaller pitch, so in spite of its extra "tooth," it is about the same size. If you are switching to 3/8" chain, from .404," use the 3/8" X 8 sprocket if you want about the same "gearing" as you had with the .404" X 7.

3/8" X 7 sprockets work well on small pro saws. These saws not only benefit from 3/8 chain (which is lighter and more flexible than 404), but the 3/8 X 7 sprocket is the smallest diameter of all standard seven spline sprockets. This gives these small pro saws low "gearing," which enables them to run a long bar with success.

For more information on sprocket size and gearing, see the section on Sprocket Tuning.

Sprocket Size & Chain "Throwing"
Most pro saw users know from experience that derailing or "throwing" a chain occurs more often when running large diameter sprockets. Most attribute this to the higher chain speeds these sprockets produce, but this is not the whole story. Large diameter sprockets also increase the distance a chain travels out of the bar on its heel. This unguided portion usually extends from the entry point on the heel of the bar to the contact points on the sprocket. The greater this distance, the more unstable the chain is.

If you are having trouble throwing chains, before you switch to a smaller sprocket, first check to see if the chain can be shortened. Some pro users wait until their chain adjuster is at its end before they remove a link from their saw chain. This is a bad practice. It is better to shorten the chain as soon as possible --always running the bar's heel as close to the sprocket as possible. This helps minimize derailures and helps extend the life of the bar heel.

A worn bar heel can also cause derailing problems. The reason is, as the bar wears, its heel becomes more narrow This also increases the distance the chain travels out of the bar rails. So, select bars that have a wider heel when running large sprockets. This usually means new bars will work better than bars with worn heels. Also, run chains as short as possible. This will increase the chain's stability.

When A Sprocket Should Be Replaced
A good general rule is: one sprocket will last for the complete life of two chains. If you are running an Oregon sprocket, another way of determining wear is to look at the wear bars. Oregon sprockets have small recesses cast into their surfaces. When the chain wears down to them, it is time to replace the sprocket. If the sprocket you have doesn't have wear bars, we recommend replacing it when it has 1/64" of wear on its surface.

From what we see in our shop, most sprockets are not replaced often enough. Too many pro saw operators apply the "If it ain't broke, don't fix it" rule instead. This is like running the tires on your truck until they won't hold air.

Sprockets need to be replaced because they get out of pitch. Sure they will eventually break if they are run long enough, but this usually doesn't occur until they are extremely worn. When a sprocket wears to a smaller diameter, it gets "out of pitch."Out of pitch conditions cause the chain to bind as it goes around the sprocket. This causes the chain to wear prematurely and affects its cutting performance. This usually occurs long before the sprocket is so worn that it breaks.

Got questions or comments on drive sprockets? Call or stop in.

Madsen's Shop & Supply, Inc. "The Pro's Choice" 360-736-1336

 

Performance Sprocket Tuning

Tuning pro saws for peak performance involves many factors, and one of them is sprocket tuning. Sprocket tuning or "gearing," as it's sometimes called, affects the performance of professional chain saws, just as it does log trucks, race cars, and many other types of engine powered machinery.

Many pro saw users do not fully understand the role sprockets play. As a result, some don't get the most out of their saws. Sometimes this occurs because they don't understand the considerations necessary for making a good choice and other times those considerations are clouded by misinformation. The purpose of these next few paragraphs is to help users better understand their needs and to aid them in the selection of equipment that best suits them.

Understanding Pitch
To understand sprocket tuning, the place to start with is with an understanding of pitch. Pitch, as measured on a saw chain, is the distance between the center of any 3 side rivets, divided by 2. Now, before any more of you write or call and ask why we simply don't say pitch is the distance between the centers of any 2 rivets, this is the reason: Some chain is designed with uneven pitch, so the distance between any two links is not always the same.

Fractional or Decimal?

Another thing that makes pitch hard to understand is the numeric format used to describe it. Today 3/8" and .404 are common pitches for pro saw chain. Strange as it may seem, one is expressed as a fraction and one as a decimal. It would be easier if we used the same format to describe both of them. However, in common practice they aren't described that way, so we are not going to suggest changing it. We will continue to refer to .404" as a decimal and 3/8" as a fraction, but we're the first to admit it's a clumsy thing to do.

Now if this sounds too much like a story problem in math class, please don't jump ahead. We promise it is just about to get fun. Even if pitch numbers are still confusing, the really important thing to know is that on pro saw chain, 3/8" is slightly smaller than .404". That's really it.

Since 3/8" chain is a little smaller than .404", when comparing sprockets with the same tooth count, the 3/8" sprocket is going to be smaller in diameter. This is important to remember because the diameter of the sprocket affects the "gearing" of the saw.

We like to use the word "gearing" when talking about sprocket tuning, because most of us have driven a vehicle with a stick shift. We know that first gear has good pulling power, but not much speed. We also know fourth has good speed but not much power.

Today's pro saws are direct drive. They don't have a transmission like the example above. There are no gears to shift. Gearing is set by the sprocket and it must be right from the beginning for the saw to perform its best. The ability to change the sprocket to one of a different pitch or tooth count is what allows the user to sprocket tune.

Sprocket Size
The pitch (diameter) and tooth count of the sprocket determines how much chain is moved on each engine revolution. In fact, sprocket size is usually stated: Pitch "by" tooth count. An example is the size: 3/8" x 8. This describes a sprocket that is 3/8" pitch with 8 teeth. That means each time the crank shaft rotates, it will move eight drive links of a 3/8" pitch saw chain.

Since we promised no more math, we'll do a little for you: This means a saw turning 13,500 RPM fitted with a 3/8" x 8 tooth sprocket is moving chain at 75 mph. Another way of saying it is the chain is moving 110 ft in one second. Pretty amazing, huh.

Now you know why today's high speed saws cut so well, but sometimes this is misleading. While it is true a fast moving chain leads to a fast cutting saw, the saw has to have enough power to cut. Simply moving the chain is not enough. It has to sever wood fiber and remove chips, too. This is where a lot of pro saw users get confused. Faster is not always better. The engine's speed and power have to be balanced with cutting characteristics.

How Sprocket Size Affects Speed & Power
Proper sprocket selection requires many considerations. These include: How much power does the saw motor really have? How long is the bar? How efficient are the cutter teeth? How hard is the wood? How sharp is the chain? How long will it stay that way? The secret is to find the place where all these factors come into balance.

Although pro saw users in the Pacific Northwest commonly use long bars to cut primarily large softwood trees, the setup is not the same for every user. Knowing some general guidelines can really help with sprocket selection.


The Best Sprockets For Saws With 65cc To 80cc Engines
For saws with engine displacements of four and five cubic inches, a 3/8" x 7 is a good all around choice. This category includes STIHL 044 and 046 and HUSQVARNA 371. These saws can effectively run long bars up to 32" with square ground chain when working in softwood trees. The effective bar length is reduced when cutting harder wood and when running saw chain with less efficient cutter teeth.

In situations where wood is soft, bar length short, and chain that is sharp and efficient, a 3/8" x 8 can work well, but it is rare. Usually when 3/8" x 8 tooth sprockets are run on saws in this size range, performance suffers.

As for .404" pitch chain, there isn't any sprocket size that yields good performance. This chain is too heavy and inflexible to work well on saws in this size range.


The Best Sprockets For Saws With 85cc To 100cc Engines
For saws with engine displacement between five and six cubic inches, the options are greater. This category includes the STIHL 064 and 066 and the HUSQVARNA 288 and 394. Saws in this category perform well with both 3/8" and .404" chain. Cutting is usually faster and smoother with 3/8", but .404" offers more durability, a wider kerf, and easier filing.

As for sprocket size, for bar lengths up to 32", a 3/8" x 8 or a .404" x 7 works well. This gearing provides good chain speed, yet still offers plenty of stump power.

When running a 36" bar and .404" pitch, the .404" x 7 remains the best size. When running a 36" bar and 3/8" pitch, a 3/8" x 7 offers more power, while the 3/8" x 8 favors chain speed.

When running a 42" bar with 3/8" chain, the 3/8" x 7 is the clear choice. This is really a pretty good combination because a 42" bar pushes the limits on saws in this category. The lower gearing that a 3/8" x 7 offers over a .404" x 7 really helps. 3/8" chain is also more flexible and lighter than .404", and this helps, too.

OREGON DURAPRO chain, or the "X" chain as some call it, works well with saws in this category. It's heavy duty cutter tooth cuts a wider kerf than standard saw chain. This is a benefit for saws in this category because this chain is tough and the wider kerf helps keep the longer bars from binding in the cut.

When running a 42" bar with .404" chain, the .404 x 7 is the best option. Even in soft wood, this pushes or exceeds the limits of the smaller saws in this category. Most pro saw users find this combination suitable for use only an occasional basis.

Bars longer than 42" do not perform well on saws in this category with any sprocket combination.

The Best Sprockets For Saws With Engines Over 100cc
For saws with engine displacements over 6 cubic inches, the .404" x 7 is usually the best choice. Saws in this category have the power to pull the large chassis of .404 chain and are not hampered by its mass and reduced flexibility. It's wide cutting kerf, high chip clearing ability, and tough design are characteristics that make .404" chain the best choice.

3/8" chain can be used on these large saws, but performance usually suffers. If 3/8" chain is used, a 3/8" x 8 is the best choice.

Large Sprockets Affect Clutch Hub Wear
Large diameter sprockets tend to wear clutch hubs faster than smaller sprockets. The larger the sprocket, the more leverage it places on the splines. As a result, saws using .404" x 8 tooth sprockets will wear splines more quickly than any of the other sprockets. Conversely, the 3/8" x 7 is the easiest on them.

Although hub wear may not be a big factor in determining the best sprocket, it is a good idea to know the larger sprockets tend to wear them faster and more frequent inspections are a good practice when running them.

Racing Sprockets
Racing sprockets such as 3/8" x 9 or larger seldom work well on production saws. They are designed to produce extra chain speed for motors that make more power than regular pro saw models.

They work only on large displacement saws with "hopped" engines. Using one on a standard pro saw will usually gear it so high there is not enough power to cut well. It will also lead to frequent chain derailing because their large diameter holds the chain out of the heel of the bar for a long distance.

Over-Speeding Saw Chain
The use of large diameter sprockets may lead to other problems such as over speeding the chain. Although we see this problem on mechanized harvesters more than hand held chain saws, all saw chain is designed to run at certain speeds. Running it beyond this speed may improve cutting speed for a short time, but it will lead to premature chain failure.

The dynamic forces generated when operating saw chain beyond its recommended speed will cause the chain to self destruct. Such breakage is dangerous and wasteful. Operating the chain within its design parameters will yield both good cutting performance and long serviceability.

Our Advice
As you can see, sprocket tuning and pitch selection involve a number of factors. Like many things there is not one "perfect" combination. You must understand your saw and consider all the factors that affect each component. In the end, the best set up is a compromise that allows the components to work together to achieve top performance.

We also want to thank you for your feedback and the many compliments on the "shop tips" we provide. You're ongoing encouragement has already got us working on more sections like this for the future. Drop us a note and let us know what you are interested in. Let us know what topics are most important to you. It is true, sometimes a little information goes a long way towards unlocking better performance from your pro saw. Helping you get the most out of your tool is why we're here... That's why we're the Pro's Choice.

Got questions about sprocket tuning? Call or stop in.