Post by tommyhnavix on May 20, 2013 15:23:31 GMT -5
I work on all brands of chainsaws at my shop. All brands seem to have their good and bad points though.
These are the guide lines I try to follow when I work on saws to cover most of the things that lead to problems. Many of these are really maintainence issues. Parts that need replaced during the service life of the saw based on usage, or even setting around not getting used!
When someone brings a chainsaw to my shop I do these things in this order. I usually consider a saw having 3 sides, top, left and right. Usually there is nothing on the bottom of a saw that needs attention.Some model of saws, such as Echo and McCulloch, have the exhaust port and muffler on the bottom of the saw. The top can be the air filter, carb, plug and fuel line section. Left hand side, ignition, recoil starter assembly and fuel and oil tank section. The right hand side covers the muffler,unless in front or on bottom of saw, the clutch assembly and bearing, chain brake assembly, the oil pump and the bar and chain group. The first thing I do is give the rope start a couple of pulls and see if we have some compression. Next I remove the muffler to check for any visable scoring of the piston or cylinder. Scoring brings things to a halt signaling EXPENSIVE REPAIRS. If no scoring, reinstall muffler. Next remove spark plug, attach spark tester to plug wire and check for good spark. Try it with kill switch in on and off possition both. Sometimes you find the kill switch does not work. Check points and condensor and replace if neccesary. Check coil gap and make sure retaining screws are tight. Next I install my compresion gauge, lock the throttle wide open with a velcro wire tie, make sure the choke is off and give the rope start four good healthy pulls. Wide open throttle gives most accurate readings. Usually anything above 130 psi a is pretty good sign it will run ok. After compression test I squirt in about 1/2 teaspoon of acetone/atf mix, install the old plug and give the rope a couple of pulls. This helps soak the rings if stuck a little and removes any gum or varnish build up while I am working on the rest of the saw. I amy recheck compression when I remove the old plug to install the new plug to see if compression improved a little. With good spark and compression, next I do the carb. kit, air filter, new fuel lines and fuel filter,clean and flush out fuel and oil tank and replace oiler lines. I remove the left side and right side covers to clean out all the accumulated saw dust and debris, especially the cooling fins. Clean the covers, check and clean, lube recoil starter and replace rope if it looks like it needs it. By now saw is looking pertty good and close to running again. I remove the clutch, drum and sprocket or rim, and bearing to replace parts as needed and lube clutch bearing as needed. If there is a cover underneath the clutch, I will remove it and clean out debris and maybe lube chain brake mechanism or lube and clean the oil pump if it's under there.
Other than installing a new plug the saw is ready to run again. I will true up the rails on the old bar if servicable or install a new bar. Sharpen the old chain if ok, or put on a new chain. I always soak a new chain or one I cleaned and sharpened in thin winter grade bar oil for a while before I install it. Nothing wears a chain faster then being dry or no oil! Now throw in a new plug and some fresh properly mixed fuel and it should be ready to start. Preset carb screws about one and one half out from bottomed for high and low. Choke it, lock throttle, turn switch on, cross your fingers and give the rope a pull ot two. After an pop, move choke to 1/2 or off and saw should start up. Warm it up a little and fine tune the idle and low mix screws. Now to set the high side I try to use a tach and set the mixture 100 to 200 rpm less than recomended no load speed. This helps take into consideration small variances in mix ratios and make the saw run a little rich, excess fuel. If no tach specs are avaiable I run the saw at wide open throttle and adjust the high side needle until I get a slight 4 cycle sound from it. This is a liitle rich. If it screams stady with no 4 cycle sound, it's lean and will die a death of lack of lubrication, over speed or over heating. A saw adjusted a little rich may not cut quite as fast but it will definately last a lot longer! Now sink it in a log and see what kind of cutting it will do!!
Some issues that might cause problems and cause more testing may be a pressure or vacuum leak caused by worn crankshaft bearings, causing crankshat seals to leak, gaskets leaking, like cylinder base gasket, crankshaft seals leaking, carb boot bad or not sealing. An ignition coil or condensor failing when hot, Carb leaking internally or externally. Oiler system or fuel tank, fuel line leaking.
I probably missed some steps here some where, but this should cover most saws.
Hope this gives some help to those new to working on saw and those who are pros also.
Should hopefully generate some discussion and service ideas and tips from other forum members
Tom
These are the guide lines I try to follow when I work on saws to cover most of the things that lead to problems. Many of these are really maintainence issues. Parts that need replaced during the service life of the saw based on usage, or even setting around not getting used!
When someone brings a chainsaw to my shop I do these things in this order. I usually consider a saw having 3 sides, top, left and right. Usually there is nothing on the bottom of a saw that needs attention.Some model of saws, such as Echo and McCulloch, have the exhaust port and muffler on the bottom of the saw. The top can be the air filter, carb, plug and fuel line section. Left hand side, ignition, recoil starter assembly and fuel and oil tank section. The right hand side covers the muffler,unless in front or on bottom of saw, the clutch assembly and bearing, chain brake assembly, the oil pump and the bar and chain group. The first thing I do is give the rope start a couple of pulls and see if we have some compression. Next I remove the muffler to check for any visable scoring of the piston or cylinder. Scoring brings things to a halt signaling EXPENSIVE REPAIRS. If no scoring, reinstall muffler. Next remove spark plug, attach spark tester to plug wire and check for good spark. Try it with kill switch in on and off possition both. Sometimes you find the kill switch does not work. Check points and condensor and replace if neccesary. Check coil gap and make sure retaining screws are tight. Next I install my compresion gauge, lock the throttle wide open with a velcro wire tie, make sure the choke is off and give the rope start four good healthy pulls. Wide open throttle gives most accurate readings. Usually anything above 130 psi a is pretty good sign it will run ok. After compression test I squirt in about 1/2 teaspoon of acetone/atf mix, install the old plug and give the rope a couple of pulls. This helps soak the rings if stuck a little and removes any gum or varnish build up while I am working on the rest of the saw. I amy recheck compression when I remove the old plug to install the new plug to see if compression improved a little. With good spark and compression, next I do the carb. kit, air filter, new fuel lines and fuel filter,clean and flush out fuel and oil tank and replace oiler lines. I remove the left side and right side covers to clean out all the accumulated saw dust and debris, especially the cooling fins. Clean the covers, check and clean, lube recoil starter and replace rope if it looks like it needs it. By now saw is looking pertty good and close to running again. I remove the clutch, drum and sprocket or rim, and bearing to replace parts as needed and lube clutch bearing as needed. If there is a cover underneath the clutch, I will remove it and clean out debris and maybe lube chain brake mechanism or lube and clean the oil pump if it's under there.
Other than installing a new plug the saw is ready to run again. I will true up the rails on the old bar if servicable or install a new bar. Sharpen the old chain if ok, or put on a new chain. I always soak a new chain or one I cleaned and sharpened in thin winter grade bar oil for a while before I install it. Nothing wears a chain faster then being dry or no oil! Now throw in a new plug and some fresh properly mixed fuel and it should be ready to start. Preset carb screws about one and one half out from bottomed for high and low. Choke it, lock throttle, turn switch on, cross your fingers and give the rope a pull ot two. After an pop, move choke to 1/2 or off and saw should start up. Warm it up a little and fine tune the idle and low mix screws. Now to set the high side I try to use a tach and set the mixture 100 to 200 rpm less than recomended no load speed. This helps take into consideration small variances in mix ratios and make the saw run a little rich, excess fuel. If no tach specs are avaiable I run the saw at wide open throttle and adjust the high side needle until I get a slight 4 cycle sound from it. This is a liitle rich. If it screams stady with no 4 cycle sound, it's lean and will die a death of lack of lubrication, over speed or over heating. A saw adjusted a little rich may not cut quite as fast but it will definately last a lot longer! Now sink it in a log and see what kind of cutting it will do!!
Some issues that might cause problems and cause more testing may be a pressure or vacuum leak caused by worn crankshaft bearings, causing crankshat seals to leak, gaskets leaking, like cylinder base gasket, crankshaft seals leaking, carb boot bad or not sealing. An ignition coil or condensor failing when hot, Carb leaking internally or externally. Oiler system or fuel tank, fuel line leaking.
I probably missed some steps here some where, but this should cover most saws.
Hope this gives some help to those new to working on saw and those who are pros also.
Should hopefully generate some discussion and service ideas and tips from other forum members
Tom