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Old 01-31-2009, 22:32   #1
XJWoody
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Chain Saw Selection and Basic Maintenance

I offer this thread as an examination of modern chain saws. I will limit its scope to gas-powered hand-held equipment, of the two-stroke persuasion. This is geared toward readers who may lack a broad knowledge of the subject, however it may be of some interest to more experienced users.

Chain saws currently available come in sizes ranging from tiny - 30cc, 1.7hp, 8#, to huge - 122cc, 8.6hp, 30#+. They are roughly split into two grades: Homeowner saws that cap out at around 60cc, and professional units that span the range.

Saws are designed for right hand operation. The operator grasps the front handlebar with their left hand, and the right hand operates the throttle and other controls adjacent to the rear handle. Some larger saws may have a wrap-around front handle, which allows a user to hold the saw from either side. These are often used in mountainous areas, where steep slopes affect the felling process. There are also ‘top-handle’ saws, which are designed for arborists for use while up in a tree, or from a lift bucket. Typically very compact and light, these specific-use saws have little application for normal woodcutting chores, and require the operator to be extra cautious during use.

In general terms, pro-grade equipment will offer better build quality, more robust controls, more advanced anti-vibration features, higher power to weight, longer service life, less complex maintenance & overhaul, and often have some interchangeability of parts. The homeowner-grade saws will typically be of lower initial cost, lower hp / #, and a little (or a lot) less quality. Each has its place, and users have their own requirements to evaluate while selecting a saw. A homeowner saw will last many years when used for its intended purposes (yard cleanup, moderate firewood cutting or light farm use.) If one needs to clear a large lot, or cut more than a couple cords of firewood per year, a professional-grade saw would be a better choice. With any small engine equipment, basic operator-level PMCS at the recommended frequency will extend the useful service life.

There are numerous manufacturers currently producing two-stroke equipment for the world & regional markets. I’ll be up front to say I own mostly Stihl, but have a couple Husqvarnas, and a small Dolmar saw. Stihl is the worldwide leader in sales and dealer coverage, with Husky, Echo, Dolmar and others bringing up the rear. Stihl and Husky (Husky's semi-twins are Jonsered, and their cousins are Poulan) have a manufacturing presence within the USA and Europe, Dolmar (and their twins sold by their parent company Makita) is made in Germany. Certain once-famous US brands (McCulloch and Homelite, specifically) are being made offshore, and are good examples of cheap Chi-com junk. Be mindful of which shore the stuff is coming from. I like to support local dealers of the major brands, who will support my purchases after the sale. Buying saws off the Internet will often provide limited warranty assistance, and possibly zero local dealer support. No matter which brand one decides upon, I suggest choosing a dealer like you would choose a spouse. They will be in it, with you, for the long haul.

Saws tend to be sold on “maximum guide bar size” and may be equipped with too much bar for the saw. This is where educated buyers can save themselves some aggravation or disappointment later on. Be honest in terms of requirements & expectations, and let that guide one towards a smart decision.

Guide bar lengths come in varying sizes ranging from 12” to 84”, with 14” to 24” being common. Selecting a suitable guide bar depends on the power of the saw, and the capability of the operator. One can cut roughly twice the bar length if an occasional need arises. Cutting softwoods such as pine and fir is easier on the apparatus than harder species like oak and hickory… this also is a factor in selecting and equipping a saw. Longer bars being used to their maximum potential require more horsepower to work efficiently.

As a basic guide, I offer this range:

30-40cc using a 14”-16” for wood -+10”
40-55cc using a 16-18” for wood -+ 16”
55-65cc using a 16-20” for wood -+ 20”
70-80cc using a 20-32” for production and or big trees
80cc and beyond is for really big timber or milling lumber. Folks shopping this range generally need little guidance, and the model selection is pretty limited.

The above is pretty conservative, and certainly not set in stone. It also shows my east-coast (flatlander with mostly hardwoods) bias towards shorter bars. Taller users may favor longer guide bars, as it lets them work without stooping over as much.

Chains come in several sizes, as well as different cutter shapes, widths & arrangements. One must match the bar groove width (gauge), chain drive link pitch and width (gauge), drive sprocket pitch, bar nose sprocket pitch, and number of drive links (bar length) together. If mismatched, these parts may not even fit up, but if they do, they will not play well together. Most bars will have the pertinent data stamped upon it, normally on the end closest to the powerhead. Some guide bars lack a sprocket-nose tip. These can be used for any pitch chain, as long as the gauge –and drive sprocket- is compatible. Note that Stihl has different bar stud patterns and oil passage journals than the Husky family and Dolmar. Unmodified, off the shelf guide bars are brand-specific.

3/8” Picco Micro or 3/8” LP (both .365” nominal pitch) low profile is found on the smallest saws.
.325” pitch comes in two gauges, NK (narrow kerf) and .063” (Stihl mid-size)
3/8” pitch has three gauges, .050” (common to any brand) .058” (Husky/Jred specific) and .063” (Stihl, typically PNW region)
Large saws may have a .404” pitch, .063” gauge.

Common cutter shapes & uses include round chisel for clean wood. Round semi-chisel is less aggressive, but tends to stay sharp longer in dirty or dead wood. Square-ground chisel chain is very aggressive in clean wood, but has a more involved process to sharpen. No woodcutting chain will tolerate contact with the ground, rocks, or other debris. My policy is such that if I even think I over-cut and nicked Mother Earth, I stop, inspect, and re-sharpen. Often, the thrown wood chips will tell on a dull chain. Sharp chains cut nice big flakes, similar in appearance to oatmeal, while dull chains tend to make powdery dust. A chain installed backwards will also cut (sort of) but makes dust and smoke as it hammers through the wood. A small saw with sharp teeth would potentially out cut a much larger saw with dull cutters.

Chains will stretch over time, and tension is adjusted via a screw on the sprocket cover adjacent to the bar nuts (sometimes this screw will be found on the front of the saw, beside the bar.) The drill is pretty simple: Unlock the chain brake, loosen the bar nuts, turn the screw to increase or decrease tension, and retighten the nuts. I apply some upward pressure to the bar as I am setting tension, to simulate the forces on the bottom edge of the bar as it contacts the wood. A chain that has proper tension will travel freely (by hand) in the guide bar groove, with a little resistance. At the center point of the bar, one should be able to pull the chain away to expose about ½ of a drive tooth. A chain that is too loose will sag away from the bar, and one that is too tight will be very difficult to turn by hand. Some modern saws have "tool-less" chain tension devices. That feature may appear handy until one pinches (sticks) their saw. What would be a minor hassle to remove the sprocket cover and free the saw head can become an impossible nightmare, and a job for a second saw, axe etc… With the older style manual adjuster, one can free the saw head, install a spare bar/chain, and liberate the stuck bar. Should one get the bar stuck, avoid wrenching & wrestling with it. This could bend the bar, damage the chain, or wreck the saw. A light-duty cutter (or one who never-ever gets their saw pinched) may be well served with a tool-less adjuster, but I prefer to stick with the non-complex manual apparatus.

Along the sharp chains track, I’ll mention that “yard trees” (or fence line trees) can often contain embedded debris like wire, bullets, nails, lag bolts, abandoned chain saw bars, etc, that can wreak havoc on your chain and could cause personal injury to self or a bystander. Often these hazards present with no advance warning, so really all one can do is be aware of the potential.

Shorter guide bars usually have chain with alternating cutting teeth every link. Longer bars and chains come with this same cutting tooth arrangement, but are often found with a “skip tooth” or “semi-skip” arrangement. These have blank links in the mix. This allows wood chips to be more effectively cleared from the cut, although taking longer to saw through. The skip and semi-skip arrangement is usually found on saws with guide bars that are over 24” length.

Some chains are equipped with carbide-tipped cutter teeth. These are intended for fire/rescue services, or for cutting extremely dirty wood like cross-ties, power poles, stumps, roots etc. It is expensive, must be sharpened with a diamond wheel, and presents an extra hazard from shrapnel if part of a tooth detaches.

continued

Last edited by XJWoody; 02-07-2009 at 14:14. Reason: clarification + more info, and grammar :(
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Old 01-31-2009, 22:33   #2
XJWoody
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Often I hear of low-kickback chains being called “safety chain.” This is a misnomer, as there is very little inherent safety. It’s design is such that as the chain travels around the top & front of the bar tip (from 0° to 90° as viewed from the right side) there are “bumpers” (humps) in between the cutter teeth which restrict how deep the teeth can bite. This helps limit rotational effects known as kickback. Most standard chains lack these bumpers, and will take a “normal” bite as it travels around the top & front of the tip. Low-kickback bars tend to have a smaller nose radius, which decreases the size of the 0°-90° kickback zone by maximizing the effect of the bumpers. Within the Stihl family, their low-kickback chains and bars are color-coded green, and their others are coded yellow. Both styles can cause horrific injuries if allowed to contact flesh.

Saws and other two-stroke tools are pretty basic in terms of care and maintenance requirements. Well cared for, a good-quality saw should give many hours of reliable service. The basics include always using fresh high-octane fuel mixed with quality oil, at the proper ratio. This is typically 50:1 for modern-era equipment. With the addition of ethanol into pump gasoline, mixed two-stroke fuel has a useful life of three months or less. Stale gas will cause engine problems (and potential for catastrophic failure) if it is used, and one should never use gas with more than 10% ethanol. There are a few ways to mitigate or eliminate the effects of ethanol, including using high-octane fuel and then only mixing up only enough for the task at hand. One can also purchase 100LL AVGAS at the local FBO, or racing gasoline from a track or speed shop. There are also long-life synthetic fuels being sold under the trade name 50fuel or 40fuel in CONUS (which comes premixed with synth. oil at 50:1 or 40:1) or Aspen in the EU & Canada. These have some favorable characteristics, but come with a high purchase price and small (1qt.) retail packaging. One usually cannot get away with running unmixed fuel. An extremely lucky user might get one tankful of raw gas through the engine, but the rest of us will cook that goose, and soon be shopping at the New Piston Store. A great practice is to add the proper amount of oil to the fuel container at home, prior to fetching the fuel. If one has similar or identical containers, take steps to clearly ID the contents within.

The sawyer needs to inspect and service the air filter every so often (every few tanks, or once a day) Simply pop the cover off, remove the filter, and tap/brush/blow off the debris. Once a year one should probably replace the fuel filter & spark plug.

Maintenance typically requires very little in the way of tools. Normally the bar attachment nuts are 13mm or 19mm, and the chain tension is set with a flat-bladed screwdriver. Stihl equipment has an abundance of T-27 Torx head bolts, while Huskys have an assortment of metric hex screws. Tools are available (which normally come with the unit and tend to grow legs. Two is one, and one is none.) that combine the bar nut & spark plug wrench with a screwdriver or Torx driver. One might need a small flat-blade driver to adjust the idle speed and fuel mixture for operation at varying altitudes. A basic “tune-up” involves nothing more than inspecting, cleaning, or replacing the air filter, spark plug, fuel filter, spark arrestor screen, performing guide bar & chain maintenance, and having a look at the chain drive sprocket wear. Air filter service and chain tension is constant (daily++ inspection & maintenance.) One should regularly clean out accumulated debris from behind the covers & shrouds, and blow out around the engine cylinder cooling fins.

Chains are maintained in the field with properly-sized round hand files or a task-specific bench grinder can be used when the teeth are extremely dull, filed unevenly, or damaged from debris impact. The files are sized for each type/style of cutter, and a flat file is used to lower the rakers down in relation to the cutter. Chain manufacturers sell files with angle and depth guides to assist those new to sharpening chains. Problems with a saw cutting diagonally vs vertical are usually a case of an unevenly sharpened chain. It is also a good idea to flip the guide bar over every so often, so the surfaces get equal wear. This also gives one a 50% opportunity to be chided for having the ‘blade on upside down’.

Problems can arise if the operator has a heavy touch. Forcing the saw through the cut and bogging it down creates a lot of heat within the clutch & drive, and can lead to premature failure of these components. Along these lines, revving the saw excessively with the chain-brake locked will create a lot of unnecessary heat and should be avoided. Saw engines are designed to run at 100% power under load… feathering the throttle in the cut is not good. Also screaming the engine at WOT under no load is a bad practice. If one is checking maximum RPMs with a hand tachometer as part of the tuning process, red-lining the engine has to be done, but one should be brief about it, and avoid excessive no load trigger-happiness.

Since the internal engine bearings and rotating assembly rely on the fuel mix for lubrication, letting the fuel run dry under a load is a bad practice and can lead to a lean seizure. Additionally, any air leaking into the engine (through failing crankshaft seals, cylinder base gasket, or the intake area) can also lead to a piston seizure caused by an overly lean air/fuel mixture. A properly tuned saw engine is crucial for optimum performance and reliability. One who is unfamiliar with setting fuel/air mixture should have their saw ‘tuned’ by an experienced technician at least once during the cutting season.

Storage is pretty simple. If it were to be packed away for long-term, or for shipping, I’d drain & flush out the oil tank, then the fuel tank, then start the saw and let it idle dry. This helps purge trapped bar oil from the passages, and gently runs the fuel in the line & carburetor out. I leave the caps off the tanks for a day or three to purge any vapors. For shorter-term storage, I simply drain the fuel and idle it dry.

Bar oil is specially blended for adhesion and minimizing wear. Used engine or gear oil is not a good substitute for several reasons, including toxicity, and suspended abrasive particles. Virgin automotive or industrial gear oils are better bad choices if that’s all one has available.

If one had a special requirement for a light environmental footprint (cutting adjacent to –or in- a sensitive watershed, such as ones own fish pond) common vegetable oil can be used in lieu of petroleum-based bar oil. There is biodegradable oil available COTS if one had a continuous requirement, but for limited specific use, HH6’s favorite brand will do.

Bar oil is metered out in proportion to the fuel used. Some saws have an externally adjustable oil pump which can increase the flow to accommodate longer bars. Most saws are preset, and often the setting will use one tank of bar oil to one tank of fuel. Filling both tanks at the same time keeps things in harmony, and be mindful which fluid goes where. Bar oil in the front tank and fuel mix in the rear tank is a common arrangement, but be clear on this before you pour. It goes without saying to insure the tank caps are secured after refilling... Stihl's new-style caps are extra-easy to befoul and this leads to oily or flammable messes and a blasphemous operator.

All two-stroke oils are not created equal. Blends for outboards, snowmobiles, and other liquid-cooled engines are not made to the same specification as those designed for air-cooled equipment. I like Stihl HP Ultra at 50:1, a fully synthetic and biodegradable oil designed for saws and other small OPE. Husqvarna XP oil is similar. If one strays too far from the manufacturers recommendations on mix oil, bad & expensive things can occur. JASO FB or API TC/TC+ is a good rating standard to look for when selecting a mix-oil that isn’t OPE specific.

Most, if not all saws currently available are equipped with a baffle or screen to prevent sparks from escaping the muffler. These devices are required to operate a saw or other motorized equipment on public lands, and are a good idea for operation anywhere, especially when conditions for a fire are favorable. Periodic maintenance to the screen involves removing any accumulated carbon or debris. Good quality mix oil and proper ratios drastically reduce carbon build-up. An added benefit to a spark screen is that it prevents mud wasps, or other uninvited guests from taking up residence within the muffler or engine during the off-season.

Chainsaws by design are quite perilous, even when everything is done right. Common sense, proper techniques, education, and familiarity with ones equipment can help minimize the risks involved, but one should be clear that it’s serious business. Thought before action, and constant attention to changing conditions are essential tasks. Basic situational awareness is key.

continued

Last edited by XJWoody; 02-07-2009 at 15:00. Reason: deleted reference to Smokey The Bear, off azimuth, clarification
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Old 01-31-2009, 22:35   #3
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I consider the following to be a minimum requirement for personal protective equipment (PPE): Leather boots, leather gloves, safety glasses, and foam earplugs. I normally wear protective chaps, and a face screen with muffs. If overhead hazards exist, I’ll wear a hard hat with screen/muffs, and I prefer to have an extra pair of eyes looking out until things are grounded. If I am sawing alone, I like to keep a telephone handy, and I keep a basic first aid kit (mainly a Cederroth Bloodstopper dressing) on my belt. PPE is no replacement for common sense, but adds a layer of protection that can reduce the severity of an injury. Saw chains are pretty filthy, so even a nick might fester up. A current tetanus booster is a plus. Protective chaps or pants consist of several layers of finely stranded synthetic material, and are covered by coarse Cordura nylon. They function by winding around and stopping the saw’s drive mechanism, ideally before it gets to carving ones meat. If it’s successful in stopping the saw without injury, you’ll have a mess to clean up before the saw will function… On the other hand, if they fail, or are left hanging in the tool shed, someone else will have a mess to clean up, with no guarantees on functionality. 9-layer chaps are $75 approx, my BC&BS E.R. co-pay is $200, so it isn’t a hard choice for me.

Fatigue and dehydration are issues to be aware of… both have negative effects on clarity and judgment. Unless things are “an emergency,” if the sawyer finds they have slipped into a drone-zone, it’s wise to park the saw for the day, or at least take a break to stretch out, water up, maintain the saw, and regroup.

There is big change coming in the world of saws/OPE. OSHA has already forced the manufacturers to quiet the noise levels. EPA regulations on emissions and EU standards on vibration levels are requiring them to completely revamp their products to comply. Enhanced anti-vibe is not a bad thing, as it allows an operator to stay at the task longer and with less fatigue. The emission output targets have been in place since 2007, but companies were able to offset their sales of gross-polluters (typically larger pro saws sold in low numbers) with higher volume sales of clean & green equipment. This carbon credit offset, “cap in trade” deal is done in 2010.

Stihl has approached their solution with hybrid 4-stroke motors (4-Mix) for trimmers & blowers, and with “stratocharged” two-strokes that re-circulate some of the exhaust gas back into the combustion process. Their first available Strato saw is the MS441, but there are several smaller homeowner-grade saws hitting the shelves in various regions. They have also delved into self-adjusting carburetors that prevent an enthusiast/operator from monkeying with the fuel/air mixture settings. The whole lineup will very shortly be revamped to comply. Husqvarna and others have their own methods & solutions, including mufflers equipped with catalytic elements, and self-adjusting carbs.

As an unapologetic troglodyte, I like my loud toys loud, smoky, and dangerous. What these evolving regulations mean is that if one has a need or desire to purchase a new “old-tech” piece of equipment, 2009 is the time to get one. 2010 is bringing change we can believe in, so we can all look forward to holding hands under the rainbow, and tickling the happy trees with our eco-friendly chainsaws.

In summation, I hope this thread has covered the basics of selecting and caring for a chainsaw. I deliberately avoided much about technique, since I feel myself unqualified to offer anything beyond the basics. If one has an interest in learning more, the USFS offers various levels of sawyer training. I took a course to become certified as an apprentice sawyer. The course was held in Troy NC, and was which was geared towards off-road and equestrian enthusiasts doing volunteer trail clean-ups within the local National Forests. It was pretty basic in nature, but I managed to un-learn some bad habits, and it exposed me to quality pro-grade equipment.

I’d like to credit the ArboristSite.com chainsaw forum as my main source reference, along with thanking Andy N. aka Lakeside53 for copious topical wisdom and Lee B. aka Plant Biologist for helping with the editing of the text.

Some suggested sources for further subject knowledge include:

www.ArboristSite.com A great website for those working in the tree trades, or the unfortunate few who’ve been bitten by the saw bug.
www.Stihl.com High quality US and German-made OPE.
www.usa.husqvarna.com High quality Swedish-made OPE.
www.dolmarpowerproducts.com High quality German-made OPE, also sold under the Makita brand in different distribution channels.
www.usa.jonsered.com Sister company to Husqvarna, they share several models with some minor differences.
www.baileysonline.com Mail order/Internet saw parts, supplies, chains, climbing gear etc…founded by Bill Bailey, who was an old-school west-coast logger and US Paratrooper. It remains a family-owned and operated business, based in Laytonville, CA.
www.oregonchain.com Oregon, a manufacturer of saw chain, guide bars, and other allied products.
www.sawchain.com Carlton, another manufacturer of chain, bars etc…

Last edited by XJWoody; 02-07-2009 at 14:53. Reason: deleted specific medical advice: NQP and off azimuth.
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Old 02-01-2009, 06:54   #4
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Thanks,, Here in the Conch Republic, we use chain saws infrequently. Palms de-foliate naturally. The hardwoods like Buttonwood don't get real good feed, so they are very slow growers. The Melaleuca, Sea Grape, Brazilian Pepper,and other soft woods are usually kept low or eliminated, as they are fodder for wind storms.

But we do need them. Think Hurricanes,, lots of things fall down in the streets,, and your yard.. No joke, after Georges in 98', the wood we cut-corded in my neighborhood could have kept Minnesota warm for a month,, well maybe Miami.. It was a lot,, took us a couple days.

I've have an old Poulan (fixed) 260, yellow pro series, 14-16 " bar. I was told to be careful to buy the older American built,, and that was 10-14 yrs ago.

It has done yeoman's work,, but she didn't crank last fall, when I wanted to trim my Mahogany. Had to barrow the neighbors..

This note is very timely.. Thanks..

If you don't mind, I would like to send it to my local friends.. it's that time of the year when we start getting ready for storm season,, at least the ones who do what should be done..
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Old 02-01-2009, 09:00   #5
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Quote:
Originally Posted by JJ_BPK View Post
Thanks,, Here in the Conch Republic, we use chain saws infrequently. Palms de-foliate naturally. The hardwoods like Buttonwood don't get real good feed, so they are very slow growers. The Melaleuca, Sea Grape, Brazilian Pepper,and other soft woods are usually kept low or eliminated, as they are fodder for wind storms.

But we do need them. Think Hurricanes,, lots of things fall down in the streets,, and your yard.. No joke, after Georges in 98', the wood we cut-corded in my neighborhood could have kept Minnesota warm for a month,, well maybe Miami.. It was a lot,, took us a couple days.

I've have an old McCulloch, yellow pro series, 16"?? bar, forgot the model. I was told to be careful to buy the older American built,, and that was 10-14 yrs ago.

It has done yeoman's work,, but she didn't crank last fall, when I wanted to trim my Mahogany. Had to barrow the neighbors..

This note is very timely.. Thanks..

If you don't mind, I would like to send it to my local friends.. it's that time of the year when we start getting ready for storm season,, at least the ones who do what should be done..
JJ_BPK before you take your McCulloch in I'd like to make a suggestion if I may. I worked at an Ace Hardware in their small engine repair shop for a couple of years in high school, we serviced/repaired McCulloch, Echo, and Homelite 2 cycle equipment (as well as all 4 cycle stuff) so I'm pretty familiar with repairing them. Most small engines are very simple and are usually very easy to get back into running condition when they stop with a little work (obviously this in not the case with some catastrophic damage but I'll get into that later if need be). If you haven't done so the first 3 things I would do would be to replace the spark plug, air filter, and internal fuel filter. The spark plug and air filter are very simple and should be self explanatory, to change the fuel filter you'll need a piece of wire that you can bend a hook in, put it into the tank and pull the filter out. That will solve probably 2/3s of most people’s problems, if that doesn't work I'd check to make sure you're getting spark. Easiest way to do this if you don't know is to take the plug out, put a screw driver in the plug socket and touch it to the block, (don't put the screw driver into the spark plug hole, could do bad things, and don't hold onto the screw driver when you pull the rope or you'll get a little shock) pull the rope and see if you have a spark (if you’re a gear head they make a little tool for this but I have no idea what they cost now probably more than getting the saw serviced), if you get a spark, then the most likely issue will be the carb. A carb rebuild kit is very easy to install, I would start by just installing the 2 rubber gaskets (pay attention when you take them out and put the new ones in the same way as the old ones came out, that will likely get you back up and running, if not there is a needle with a small/thick o-ring type gasket in the kit that goes below the needle, that will need to be swapped out, the easiest way to get it out is to use compressed air, if you need/desire to go that far I can pull a carb and take some pictures of where to put the air nozzle to get that little gasket to pop out. If/when you get that out you need to make sure the new gaskets flat side is facing out with the round side with the small seam faces away from the needle. Now if you put the do all of the above and it’s still not running it’s possible you have bigger issues, next most common are the magneto going bad but you’ll know that when you do the spark test, after that you’re probably talking major internal damage, though if you mix your gas properly that’s probably not the case.


Let me know if you need/want the pictures.

When I was working at Ace we did what we called check ups which cost about 50 bucks, which was basically just putting a new air/fuel filter, new plug, fresh gas in and sharpening the chain, usually took less than an hour and got more than 2/3s of saws back up and running.
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Old 02-01-2009, 09:26   #6
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Great thread, thanks XJWoody!

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Old 02-01-2009, 09:36   #7
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Thanks for mentioning storm clean-up. I grew up in the countryside west of Boston, so our saw use was 98% firewood harvesting, and 2% debris clean up. Dad had an older (70s) ProMac something or other, approx 60cc -80cc class. It was a pretty coarse piece of kit, but it was reliable, and pretty much state of the art for it's era. Mr H can no doubt relate, and I bet he still has an oversized thumb from mashing the chain oiler.

When Hurricane Fran blew through NC some years ago, we lost a number of larger oaks. Several didn't fall completely, and were snagged by otherwise healthy trees. I was equipped with close to zero skills, and a little Husky 41, but we slogged through the mess and netted a few years worth of wood to burn. In hindsight, I was way out of my league, under equipped, and quite lucky I didn't get squashed or filleted. The extent of my PPE was a pair of gloves, Oakleys, and workboots. It was summertime, so I can imagine shorts and a tee rounded out the duty uniform. After a couple sessions, I taped some foam pipe insulation to the front handlebar to fend off vibration (which conflicted with the chain brake, so it was defeated with a zip-tie. FUBAR, soup sammich, high-order jackassery etc... Live & learn? Absolutely. I share this as a good example of bad practices. I was "that guy" in full regalia.

I shall work up a section on troubleshooting, since even with meticulous care, sometimes our junk just won't light off. There are a few steps to follow, and they apply to most any internal combustion engine. It may not ultimately help one fix the issue, but it should get them pointed towards resolving it.

If I may inquire of the currently-serving QPs, if your team has a saw on inventory, what brand/model is it? Is there a standard-issue NSN piece, or is it something that would be local-purchased based on need? I can't imagine that a team with a tropical focus would have the same requirements as a team that works in the frozen tundra, but the Army works in mysterious ways. I would think the primary uses might include clearing a camp site or LZ, field construction of structures, and creation or reduction of obstacles. If this is a breach of TTP, I'll go do some log PT. I don't really have need to know, and I'd hate to be the next cat that curiosity killed.

Don

Last edited by XJWoody; 02-01-2009 at 09:49.
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Old 02-01-2009, 10:23   #8
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Great thread, NTM timely. Your profile says "Moore County". Who has the best small engine shop in the Aberdeen/SP area? I've resurrected my Stihl enough times that it needs a professional touch (or a stake through the carb). Spring is fast approaching and all my 2-cycle engines need serviced. I've about reached the conclusion that extended periods of disuse cause more problems than anything other than flagrant abuse.
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Old 02-01-2009, 11:07   #9
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Small engine troubleshooting

Despite our best efforts to the contrary, there are times when a piece of equipment refuses to start. I'd like to expand a bit on what Defender968 posted above. (He was spot on BTW)

Most gasoline-powered equipment has three basic requirements to run: Air, fuel, and spark.

The air is the easiest to check & rule out. Inspect the air filter and clean as necessary. Peer into the carb while the filter is off to insure there are no obstructions. Operate the choke controls and observe (there would be a metal plate that rotates when this control is engaged, blocking off the airway.) Also operate the throttle trigger and insure it's not sticking or that the linkage is disconnected. One could leave the filter and shroud off for the next steps, but do reinstall these before normal operation.

Fuel (more specifically, fuel and air under compression) is the next thing to check. A quick & dirty compression check is to hold the saw up, grasp the starter handle, and let the saw drop. With "good" compression, the saw should hang, or very slowly drop. (blup.......blup......blup etc) If the saw freely drops or offers little resistance, something is worn internally. (Blupblupblupblup) Of course, if the internals are locked up, the rope wont pull, and the show is over until those issues are addressed.

Some pro-grade saws have a compression release device on the top or side of the cylinder. It's function is to allow for an easier pull when starting. If this device is engaged or stuck open, there is no hope of getting good compression, and the engine will likely not run. Rule this out.

A compression gauge may give a closer idea what's going on inside, but these diagnostic tools vary in application. A saw has a very small volume, so an automotive gauge may give falsely-low readings on a small engine. In a nutshell, 180psi would be outstanding, down to about 130-140 psi is serviceable, and below 125psi indicates the chestnuts are roasted. If the compression is very low, one could remove the muffler and carburetor, then slowly rotate the crank and observe the condition of the piston, rings, and cylinder bore. If things appear pretty smooth, or just lightly scuffed, that is good. If it appears to have spent it's summer vacation in Mogadishu... bad news & steel yourself up for a visit to the New Engine Store.

If the saw has an unobstructed airway, holds good compression, and has known good fuel, the only thing left is to check for spark. Remove the spark plug and inspect it (or if in doubt, replace with a new one) it should have only light brown deposits on it. Dark oily deposits indicate an overly rich condition, and one that is very white indicates a lean condition. "Reading" a two-stroke plug is somewhat voodoo science, so I default to swapping in a fresh part.

While the plug is removed, it's a good idea to pull the engine through a few times to purge any accumulated fuel. One might have to invert the saw, and pull, just to insure that no fuel has pooled up in the valley below the crankshaft. If one has flooded the engine badly, it may take several hours to clear it out. (Pull awhile, let it sit, repeat as necessary.) Once things are sufficiently dried out, confirm that the kill switch is in the "run" position, attach a known good spark plug to the lead wire, ground the plug electrode against the cylinder (this may take several hands, or rigging up some apparatus) and pull the starter. One should see a bright blue spark at each revolution. As Def968 advises, do not become part of the ground path. Letting your spouse or children hold the plug is an option However these folks may be caring for you in your old age, so memories of Grandpa's workshop should probably not include high-voltage. Failure to achieve a nice fat spark indicates something is amiss with the electronics (The kill-switch is in the 'run' position, yes?) Older saws & tools had points & condenser that could fry, wear, or come out of adjustment, but new equipment is pretty much a case of it's working or it's not.

Some equipment has an air-purge bulb ('primer') that forces the air out of the carburetor passages. Like anything rubber or plastic, it will degrade over time. If this is inop or leaking, it's fairly easy and inexpensive to replace. Same applies for fuel lines. These are also sacrificial parts, and especially so with ethanol blended with our gasoline.

If the saw runs, but seems to want to hold it's revs, or reluctantly idles back, this is not a new-found cruise control... It indicates an air leak somewhere which needs addressed ASAP. Your expensive tool is heading towards becoming a Chernobyl replica at a double-time. See "New Engine Store" above.

That's about it for two-stroke engines, at the very basic level. Snow-mos, watercraft, dirt-bike/quad engines etc... may have advanced sub-systems such as fuel injection, variable port timing ('power valves') and other features to increase performance, reliability, and control of noise or emissions. These all add complexity, and have their own specific procedures for troubleshooting.

Last edited by XJWoody; 02-07-2009 at 15:12. Reason: sound effects
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Old 02-01-2009, 11:23   #10
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Chain saw

A chain saw for most is a rarely used item. Was running fine when it was put in the back of the shed 3 years ago.

Ice storm, tree down, I know I've got one around here somewhere - pull and pull and pull and it never starts.

It's one of those things that runs best on fresh gas/oil.

Oh, and a sharp chain. Again, most get put away after use - and the chain is dull. A dremel tool with the chain kit and you can have it sharp as new in 10 minutes.

Edited to add - I own a Poulan and baby Homelite

Last edited by Pete; 02-01-2009 at 11:29. Reason: add my saws
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Old 02-01-2009, 11:24   #11
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I have to put in a good word for Sta-Bil fuel stabilizer.

My Stihl saw started and ran fine after sitting for four years with the same gas in it that had been stabilized. I would not recommend testing it for that long, but it should give you an idea of how well it works.

I have heard people say that you are better off leaving a little gas in the carb to keep seals from drying out and dust from getting into things.

TR
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Old 02-01-2009, 11:29   #12
Bill Harsey
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XJWoody,
Great post and a good reference to have on record here.

Could I offer a couple things from an Oregon perspective?
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Old 02-01-2009, 11:38   #13
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Quote:
Originally Posted by Defender968 View Post

If you haven't done so the first 3 things I would do would be to replace the spark plug, air filter, and internal fuel filter. The spark plug and air filter are very simple and should be self explanatory, to change the fuel filter you'll need a piece of wire that you can bend a hook in, put it into the tank and pull the filter out. That will solve probably 2/3s of most people’s problems, if that doesn't work I'd check to make sure you're getting spark. Easiest way to do this if you don't know is to take the plug out, put a screw driver in the plug socket and touch it to the block, (don't put the screw driver into the spark plug hole, could do bad things, and don't hold onto the screw driver when you pull the rope or you'll get a little shock) pull the rope and see if you have a spark (if you’re a gear head they make a little tool for this but I have no idea what they cost now probably more than getting the saw serviced), if you get a spark, then the most likely issue will be the carb. A carb rebuild kit is very easy to install, I would start by just installing the 2 rubber gaskets (pay attention when you take them out and put the new ones in the same way as the old ones came out, that will likely get you back up and running, if not there is a needle with a small/thick o-ring type gasket in the kit that goes below the needle, that will need to be swapped out, the easiest way to get it out is to use compressed air, if you need/desire to go that far I can pull a carb and take some pictures of where to put the air nozzle to get that little gasket to pop out. If/when you get that out you need to make sure the new gaskets flat side is facing out with the round side with the small seam faces away from the needle. Now if you put the do all of the above and it’s still not running it’s possible you have bigger issues, next most common are the magneto going bad but you’ll know that when you do the spark test, after that you’re probably talking major internal damage, though if you mix your gas properly that’s probably not the case.


Let me know if you need/want the pictures.

When I was working at Ace we did what we called check ups which cost about 50 bucks, which was basically just putting a new air/fuel filter, new plug, fresh gas in and sharpening the chain, usually took less than an hour and got more than 2/3s of saws back up and running.

I chk'd,, it's a Poulan 260,, I knew it was yellow/black,, whoops..

I did 1 & 2 the day of.. I also put fresh gas in and liberally goosed it with either carb spray.

My thoughts at the time, was I need a carb re-build.. I purchased it from a guy that had it 4-5 yrs,, he cut one 3" maple and put it the cellar. I know it was maple, because the case and chain guide was packed full,, he never cleaned it. Otherwise it looked brand new. I've had it 10 yrs or better.. My concern was the carb re-build parts were long gone..

Anyone know if there are sources for Poulan 260 parts??

I will take a look at the internal filter..

I have Federal Jury Duty the next 2 weeks,, starts Monday,, I may get back to you after..

Thanks for the helpful note..
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Old 02-01-2009, 11:47   #14
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Originally Posted by Peregrino View Post
Great thread, NTM timely. Your profile says "Moore County". Who has the best small engine shop in the Aberdeen/SP area? I've resurrected my Stihl enough times that it needs a professional touch (or a stake through the carb). Spring is fast approaching and all my 2-cycle engines need serviced. I've about reached the conclusion that extended periods of disuse cause more problems than anything other than flagrant abuse.

Sir, I'd be reluctant to advise a small engine shop locally. I love my loud toys and place that in the same category as which hospital I'd like to admit my grandkids... D. None of the above.

Carthage Saw & Mower which is on 15-501, N side of town, across from the old Brathaus resturant building has helped me out of a jam, and is my go-to source for Stihl & Husky parts. I've had little contact with their service department, but they did get my Farm Boss back in action (a fouled up carb from poor storage) after it soundly defeated me.

I hesitate to talk bad, but the small engine shop on US1/15-501 near downtown Aberdeen incurred one (and only one) FTFSI violation. If I badly needed a new chain or some other doo-dad when I was down there, I might go back... but it would be under duress, and would certainly not make a special trip.

If one wanted to travel a bit, Amick's in Asheboro (Bus 220, N side of town) is a very good shop. They sell Stihl, Husky, Dolmar and several other name brands. I trust their competence and ethics, and they have always treated me fairly. That is the highest honor I could bestow on a shop. The snag is only that it's pretty inconvenient. At least they have Saturday hours, which is rare in that business.

I fully agree that even properly stored, equipment tends to go bad over time. Fuel lines and other rubber/plastic bits decay, seals become hardened and fail, electrical gremlins conspire, and (around here anyway) insects roost up in the nether-regions.

How much equipment are you talking about Sir? I am all about the "Teach a man to fish..." drill. I'm not a Pro (be very wary of a mechanic that "will work for beer") but I have an occasional fit of brilliance.

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Old 02-01-2009, 12:07   #15
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XJWoody,
Great post and a good reference to have on record here.

Could I offer a couple things from an Oregon perspective?
Mr Harsey,

Being that you have likely forgot more about saws and forestry operations than most of us will ever know, by all means please share with us what you feel relevant.

I'm looking forward to it, especially things that involve improvised tools, field expedient remedies & techniques etc...

Thanks!
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