SawTroll
Information Collector
A tach will tell what is going on - they are always nice to have, and specially with rev limited saws! :msp_smile:
Killed my Dolmar :(
- Thread starter loganj01
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A tach will tell what is going on - they are always nice to have, and specially with rev limited saws! :msp_smile:
Vibes
Addicted to ArboristSite
I'm with you norm. I have been cutting hunting lanes at my sportsmans club. I asked them if they could spring for the gas. They said just use what was in the shed. No way!!!!
loganj01
ArboristSite Operative
Believe it or not, I'm also really picky about my saw gas. I only buy from a little store here by the house that has ethanol free gas and I always use either Stihl or Husky oil. I did wonder if I might possibly have messed up the mix somehow so I dumped the remainder of the gas I had mixed in the tractor and mixed up a fresh batch. I also "rinse" the oil bottle out when I mix it. I also wondered about an air leak...I still haven't ruled it out. To put things in perspective, the Husky is a 336 that had problems when I got it...the Stihl is a very old 028 that hasn't run in years. I recently got it back from the shop and it seems that the electronic doo-dad they put in the ignition didn't solve the problem. Anyway, I suppose it sounded like I had three new top brand saws sitting here that I'd screwed up...not the case. I'm still learning about the saw tuning (obviously...lol) but I don't think I'm bumping the limiter on the 7900 and here's why. Please correct me if I'm wrong...I'm used to it...wife does it a lot. I backed the high speed screw out 1 turn from seated, cranked the saw and let it idle for a minute to warm up. It wouldn't rev up much so I backed out another 1/2 turn or so. When I had it adjusted where the saw was really screaming, I backed it out until there was a noticeable drop in rpm and a very definite burble. I needed it running yesterday because I had promised a friend that I'd come section a large poplar into saw logs for him...his saw wouldn't reach through it. I'm going to pull the muffler in a little while and look at the piston. Thanks in advance for advice and constructive criticism 
Ok...pulled the muffler and looked at the piston. It's still slick with just a few flakes of the black coating that came on it. No scoring on the side or on the top edge at the exhaust port. This top end has about an hour of run time.
Ok...pulled the muffler and looked at the piston. It's still slick with just a few flakes of the black coating that came on it. No scoring on the side or on the top edge at the exhaust port. This top end has about an hour of run time.
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NORMZILLA44
Addicted to ArboristSite
Thanks TDI Rick, and Vibes. I am glad to see guy's that mix like me. Where I work at the county I have seen guy's straight gas, half mix, double mix. LOL! If one of my saws goes down I cant sleep at night! Loganjo1 that mix thing was just me saying the way I do things, and being long winded LOL! I think everybody understand's youre situation nobody wants to critisize you, but we all wanna find out what the $!#@$# happened? That just sucks man when youre good saw goes down. I have five, and backups for the big stuff too, even if it happened to me with extra's I have I would be pulling my hair out! Worse for you sounds like youre only big saw.
loganj01
ArboristSite Operative
Yeah...it is my only big saw. It was pretty embarrassing to tell the wife I burned it up too... I got the single arched eyebrow stare with the "your NEW saw?" with pretty much the same inflection she might have used if I'd told her I just ran over one of the kids...lol. Anyway, I checked the compression and had 150 psi. Took a pic of the plug too...pretty sure this saw is not running lean now. Sorry for the lousy pic...cellphone doesn't focus that close I guess.View attachment 186358
NORMZILLA44
Addicted to ArboristSite
Man, that sucks. I feel for you little buddy, and I know how women are. They don't realize that mechanical-power equipment, well stuff happens. Is it going now? When that thing first quit was it hard to pull or comp the same?
Roofgunner
ArboristSite Member
lean saw
I read almost all the responses to this thread. My Husky 55 slowed up and scored the front of the piston (exhaust side) while on a WOT run through a cherry tree about three years ago. I was under the impression that if the saw went lean (air leak) the exhaust side would score. I it was not enough oil in the mix it would scar on the intake side. On my 55 I never could actually saw why it went lean, even after inspecting everything. I just rebuilt it with a Baileys kit, new seals. The crank and bearings were OK. Actually the saw runs better now, than when new. I've come to learn that if a saw idles well, accelerates steady, and starts easily, it's more than likely OK. I think that it's also important to read the spark plug, esp. when you do a plug "chop" at full throttle. It's best , I think to replace everything related to an air leak when you do the rebuild.
I read almost all the responses to this thread. My Husky 55 slowed up and scored the front of the piston (exhaust side) while on a WOT run through a cherry tree about three years ago. I was under the impression that if the saw went lean (air leak) the exhaust side would score. I it was not enough oil in the mix it would scar on the intake side. On my 55 I never could actually saw why it went lean, even after inspecting everything. I just rebuilt it with a Baileys kit, new seals. The crank and bearings were OK. Actually the saw runs better now, than when new. I've come to learn that if a saw idles well, accelerates steady, and starts easily, it's more than likely OK. I think that it's also important to read the spark plug, esp. when you do a plug "chop" at full throttle. It's best , I think to replace everything related to an air leak when you do the rebuild.
NORMZILLA44
Addicted to ArboristSite
Very good point's, but I do agree with Saw troll 100 percent. I would have to find what caused the problem first, if nothing else for my own sanity. My 2101 had me and the shop chasing a few things, and I asked alot of questions on this site. Everything pointed to the carb, wouldn't tune or stay tuned, and just when I thought it was running right it changed. The shop rebuilt the carb. I picked it up ran great. Got home next day would'nt idle. Went back they dropped everything, and jumped on it checked it out, re tuned we log tested it, best it ran yet. Thought we had it, couple days later, idle, and winding up. The shop found a blown crank seal, and the previous symptoms all pointed at the carb, they were blown away it even ran with a air leak that bad. And ran so good, and tuned twice, and the a 180. Definately learned I was looking to hard at the obvious.
loganj01
ArboristSite Operative
I don't have the tools to pressure test or vacuum the crankcase to see if there is a problem with a seal. It's just over a year old and only used for cutting firewood for me and my in laws so it doesn't really have that many hours on it. I'd be surprised if it had a bad seal but stranger things have happened. It doesn't seem to tune very well...don't see much response to the low speed jet. Bear in mind that I don't really know what response I should get but all it does is quit running while I'm adjusting it...doesn't seem to matter which way I'm turning the screw. If I ever run it out of gas I am so screwed...it'll take about 30 pulls to get it going again if it starts at all. Maybe I should take it and have the crankcase tested and if it checks out, start looking at the carb?
Old Stihl 028 came in at 165 psi compression and piston looked great on the exhaust side so I'm thinking maybe it wasn't the gas?
Old Stihl 028 came in at 165 psi compression and piston looked great on the exhaust side so I'm thinking maybe it wasn't the gas?
NORMZILLA44
Addicted to ArboristSite
Yeah that's tough, and the 2101 story may not pertain to you. Just brought that up pointing out that sometimes fresh eyes, and or help is needed, but I would definately take it in if you have a good shop. Certainly for piece of mind to find the root of the problem. Could also be something smaller if an air leak. Not just crank seals may cause one. Definately puzzling, and help needed.
Roofgunner
ArboristSite Member
I'll give suggestions
Here are some idea's: Could the vent to the fuel tank be hindered to reduce fuel to the carb creating a lean condition? If you had fuel that had ethanol (which is supposed to be only 10%) in it and it was more than 10 (which has happened) percent could this cause the saw to overheat, as I think it would??? If there is enough play in the bearings this could cause an air leak, esp. if the flywheel is off balance. (I think this happened with a little Husky 36 I have and will rebuild-after 17 years of use- the flywheel "key" sheared through it out of time and the bearings had rough areas upon disassembly). I would think the least likely areas would be the base gasket area or where the engine halfs go together if that's the way it's built, since these are sealed with sealer, gaskets or both. I would check the compression release if it has one. But if it has a new or rebuilt carb and the saw run erratic and won't respond to adjustment then air is leaking. If there is a way to run the saw and squirt some carb cleaner, etc. around the areas where air could get in this would alter the rpm's and probably cause the saw to stumble or quit. My only other comment at this point is that the weakest area in a saw, in my opinion is the seals. They are subject to heat, friction, fuel, oil, and they can dry and probably go bad faster with ethanol in the gas and who knows what might be in oil mixes that wears them. Also, just because you put a saw away and it ran, it could sit a while and you go to start it and all the sudden it has an air leak. This is what happened with the 36. It ran fine. The carb had been rebuilt once and all the intake stuff gone over. I replaced the seals. I go to start it, after a few months. It didn't go on the second or third pull. Then it ran and acted crazy. I figured it was an air leak somewhere. Upon diassembly I found: fly wheel key (which is aluminum cast into the flywheel) sheared, and a slight amount of play in the crankshaft but not much but maybe enough. I pulled the whole motor apart and when I spun the bearings I could feel they had rough spots. The piston and bore wear clean, no scarring, ring was free, bottom and top end caged rollers were fine. This was after 16/17 years of 100 to 1 Amsoil, ether in the CA. gas, and use in an almond orchard. Keep investigating and learn. Just because I can, I'm getting new bearings, seals, and flywheel and I'll put it back together.
Here are some idea's: Could the vent to the fuel tank be hindered to reduce fuel to the carb creating a lean condition? If you had fuel that had ethanol (which is supposed to be only 10%) in it and it was more than 10 (which has happened) percent could this cause the saw to overheat, as I think it would??? If there is enough play in the bearings this could cause an air leak, esp. if the flywheel is off balance. (I think this happened with a little Husky 36 I have and will rebuild-after 17 years of use- the flywheel "key" sheared through it out of time and the bearings had rough areas upon disassembly). I would think the least likely areas would be the base gasket area or where the engine halfs go together if that's the way it's built, since these are sealed with sealer, gaskets or both. I would check the compression release if it has one. But if it has a new or rebuilt carb and the saw run erratic and won't respond to adjustment then air is leaking. If there is a way to run the saw and squirt some carb cleaner, etc. around the areas where air could get in this would alter the rpm's and probably cause the saw to stumble or quit. My only other comment at this point is that the weakest area in a saw, in my opinion is the seals. They are subject to heat, friction, fuel, oil, and they can dry and probably go bad faster with ethanol in the gas and who knows what might be in oil mixes that wears them. Also, just because you put a saw away and it ran, it could sit a while and you go to start it and all the sudden it has an air leak. This is what happened with the 36. It ran fine. The carb had been rebuilt once and all the intake stuff gone over. I replaced the seals. I go to start it, after a few months. It didn't go on the second or third pull. Then it ran and acted crazy. I figured it was an air leak somewhere. Upon diassembly I found: fly wheel key (which is aluminum cast into the flywheel) sheared, and a slight amount of play in the crankshaft but not much but maybe enough. I pulled the whole motor apart and when I spun the bearings I could feel they had rough spots. The piston and bore wear clean, no scarring, ring was free, bottom and top end caged rollers were fine. This was after 16/17 years of 100 to 1 Amsoil, ether in the CA. gas, and use in an almond orchard. Keep investigating and learn. Just because I can, I'm getting new bearings, seals, and flywheel and I'll put it back together.
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