you might be right about that. does that mean piston needs replacing?
please help me figure out what to do with my ms660.
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If there is material detached from the piston you need to know how and why!.. eg: the same object that impacted the top of the piston could have removed the material from the piston window.
You probably need to have someone who knows saws to look at it & find the root cause of why the saw is in this condition, otherwise you could be throwing your money away without actually fixing it throughly.
Thansk
Thansk
It didn't take me that long to take it apart, so I think I want to try and put it back together , clean the carb, then see whats really causing the saw to act that way. Maybe I will clean the carb after I run it after reassembly, just to keep track of any possible changes. Please someone tell me how best to clean up the carbon deposits and what to use to hone the piston and possibly the cylinder ?
That appears to be a reflection of the locating pin on the oily ring.
Personally, I would wipe the cylinder walls with a lint free rag and some brake cleaner and allow to dry. Apply a light coat of 2-stroke oil to the walls of the cylinder with your fingers. Clean the piston and ring grooves by spraying it down with brake cleaner and install it on the rod. Add a drop or two 2 stroke oil to the rod pin and bearing, to the rings and ring grooves, and lightly coat the piston walls then assemble it. Don't go crazy with the oil, just a little so there is no metal to metal contact... The one pic of your piston looks like you had some debris pass through the combustion chamber but did not damage anything. I believe your issue is fuel related and you need to verify the tank vent.
interesting thread! pretty big saw! I consider my 026 a pretty big saw... but then also my Echo CS-271T lol, well it thinks it is... 
engine work: always interesting...
first - congrats on efforts to take cyl & piston off/out! and pix look pretty good, too.
as has been suggested prob fuel related or fuel/air ratio... ie air, or leaks, etc...
well, u say your 'almost new' 660 with only 150 hours on it. new? hardly in my books... that is close to running it a full month of work days... 8 hrs a day, 5 days a week... almost 4 weeks. any thing... but new, imo...
you mentioned sandpaper to clean. hope u dint use that on inside of cyl. chances of getting silica into the transfers etc very high. even if blown out. if u did, it will take a full-on engine builder's cleaning just short of a vat. if it was mine, and that was the case... several cleanings with laquer thinner. then... as hot as I could stand it or get it... hot very soapy water... Dawn... clean it out sveral times and air blow clean each time, then clean sev times more in more clean laquer thinner. same with piston... in any event, if mine that is how I would clean it!
engine cylinders have been successfully honed by hand since the days of Model T's... with wet/dry sanding paper, not wood sanding paper... and gasoline used as a cutting agent. not n down, but round n round. if cyl has nikasil... prob does... u can't really hone it easily, but can clean it up so rings can reseat or new ones will. if it was mine, I would not remove those rings! too easy to bend. I like ur idea of cleaning it up and reassembling it. but u may want to vac test it, or have it done. I would never use and never have in all of my engine building projects a ball hone!! some by hand, some by machine shop doing the boring and also precision hone in precision hone machine, kinda like a specialized mill...
you said u r running ethanol free fuel and the stihl oil... well, hmm. first question is are u adding oil to it? since the pre-mixed come 50:1 pre mixed. if u mix ur own, use the low ash stihol oil. piston top suggests rich mode. if plug coming out, be sure u have it torqued to proper torque. 18-ft #'s... should be ok, as a min, think its 20-22 ft-lbs#... set the plug nipple with some locktite blue if in doubt. properly installed plugs do not come loose!
you, imo... should not have to ask us how to clean your air cleaner! but... if in doubt just buy a new one. expecially since u have probs that could be air related. compressed air too high can damage them!
as is suggested, a carb rebuild would be a good idea. but it must be done meticulously and correctly... there are no shortage of good how-to's on utube. also for saw reassembly go find DonnyBoy's vids... he does a 360 I think it is... and covers all the important issues of rod, wrist pin bearing, piston assembly etc and amouts of oil to use. I like his techniques and vids.
a new saw's piston will have the machining grooves on it that also help hold oil on the piston skirt, etc. yours, as u state are gone. appear to be plumb worn off! could be causing piston asked to work hard to heat up beyond normal, transfer heat to piston top. damaging or cntributing. even my 044 project that was acquired by an arborist pre-owned and run daily for 3 years before it stuck the rings in ring lands and I acquired it... has them!!! I can only see ur's just under the bottom ring groove. so the piston is quite worn on the skirts given the wear pattern. a piston to cyl wal measurement is warranted. but be advised, Meteor pistons weigh a bunch more than OEM. although rebuilders I read about say they run ok. for my 044 project I am whittling on M piston to reduce weight and will run OEM wrist pin w/new OEM bearing... since its lighter, the original pin. and as used as it is, wear is not measurable within .**** and is burnished at best...
I haven't watched your vid. you could be running marginally lean, ie oily rich. that 066 is a big saw... if u r running it WOT for nearly a month... it will heat up inside under those kind of conditions... your saw hasn't taken a full powder yet... but if run that way once reassembled... it's heading down that path. as indicated by damage to top of piston crown's outer edges...
as I say... interesting thread, hope u will continue to update us on ur progress, decsions and the outcome...
sending Best Wishes! ~
engine work: always interesting...
first - congrats on efforts to take cyl & piston off/out! and pix look pretty good, too.
as has been suggested prob fuel related or fuel/air ratio... ie air, or leaks, etc...
well, u say your 'almost new' 660 with only 150 hours on it. new? hardly in my books... that is close to running it a full month of work days... 8 hrs a day, 5 days a week... almost 4 weeks. any thing... but new, imo...
you mentioned sandpaper to clean. hope u dint use that on inside of cyl. chances of getting silica into the transfers etc very high. even if blown out. if u did, it will take a full-on engine builder's cleaning just short of a vat. if it was mine, and that was the case... several cleanings with laquer thinner. then... as hot as I could stand it or get it... hot very soapy water... Dawn... clean it out sveral times and air blow clean each time, then clean sev times more in more clean laquer thinner. same with piston... in any event, if mine that is how I would clean it!
engine cylinders have been successfully honed by hand since the days of Model T's... with wet/dry sanding paper, not wood sanding paper... and gasoline used as a cutting agent. not n down, but round n round. if cyl has nikasil... prob does... u can't really hone it easily, but can clean it up so rings can reseat or new ones will. if it was mine, I would not remove those rings! too easy to bend. I like ur idea of cleaning it up and reassembling it. but u may want to vac test it, or have it done. I would never use and never have in all of my engine building projects a ball hone!! some by hand, some by machine shop doing the boring and also precision hone in precision hone machine, kinda like a specialized mill...
you said u r running ethanol free fuel and the stihl oil... well, hmm. first question is are u adding oil to it? since the pre-mixed come 50:1 pre mixed. if u mix ur own, use the low ash stihol oil. piston top suggests rich mode. if plug coming out, be sure u have it torqued to proper torque. 18-ft #'s... should be ok, as a min, think its 20-22 ft-lbs#... set the plug nipple with some locktite blue if in doubt. properly installed plugs do not come loose!
you, imo... should not have to ask us how to clean your air cleaner! but... if in doubt just buy a new one. expecially since u have probs that could be air related. compressed air too high can damage them!
as is suggested, a carb rebuild would be a good idea. but it must be done meticulously and correctly... there are no shortage of good how-to's on utube. also for saw reassembly go find DonnyBoy's vids... he does a 360 I think it is... and covers all the important issues of rod, wrist pin bearing, piston assembly etc and amouts of oil to use. I like his techniques and vids.
a new saw's piston will have the machining grooves on it that also help hold oil on the piston skirt, etc. yours, as u state are gone. appear to be plumb worn off! could be causing piston asked to work hard to heat up beyond normal, transfer heat to piston top. damaging or cntributing. even my 044 project that was acquired by an arborist pre-owned and run daily for 3 years before it stuck the rings in ring lands and I acquired it... has them!!! I can only see ur's just under the bottom ring groove. so the piston is quite worn on the skirts given the wear pattern. a piston to cyl wal measurement is warranted. but be advised, Meteor pistons weigh a bunch more than OEM. although rebuilders I read about say they run ok. for my 044 project I am whittling on M piston to reduce weight and will run OEM wrist pin w/new OEM bearing... since its lighter, the original pin. and as used as it is, wear is not measurable within .**** and is burnished at best...
I haven't watched your vid. you could be running marginally lean, ie oily rich. that 066 is a big saw... if u r running it WOT for nearly a month... it will heat up inside under those kind of conditions... your saw hasn't taken a full powder yet... but if run that way once reassembled... it's heading down that path. as indicated by damage to top of piston crown's outer edges...
as I say... interesting thread, hope u will continue to update us on ur progress, decsions and the outcome...
sending Best Wishes! ~
fastLeo151
Addicted to ArboristSite
O my!
LegDeLimber
Addicted to ArboristSite
Has anyone seen a good view of the combustion chamber?
Near the edges, Looks to be some lines of missing carbon, but the pic isn't focused on the chamber.
My first thought was piston contact, But..., I can't see any corresponding marks on the piston top.
So I'm wondering about detonation.
All that cornflakey looking carbon and the 5th pic in post #21
the piston has a lot of little dimples and the edge has many displaced areas.
I'm wondering about either a foreign object(s) or detonation.
Detonation comes to mind because of all those white edged flakes of carbon in the head and on the piston.
Does anyone have the specs for ring groove clearance?
I'd be curious as to if the ring grooves are getting hammered out any.
How about a view of the bottom end?
Have we seen the piston pin and bearing?
What's the lower end looking like?
Anything amiss there?
I'd be wanting to know why the piston is dinged.
But some people think that I "sweat the small stuff" too much.
Near the edges, Looks to be some lines of missing carbon, but the pic isn't focused on the chamber.
My first thought was piston contact, But..., I can't see any corresponding marks on the piston top.
So I'm wondering about detonation.
All that cornflakey looking carbon and the 5th pic in post #21
the piston has a lot of little dimples and the edge has many displaced areas.
I'm wondering about either a foreign object(s) or detonation.
Detonation comes to mind because of all those white edged flakes of carbon in the head and on the piston.
Does anyone have the specs for ring groove clearance?
I'd be curious as to if the ring grooves are getting hammered out any.
How about a view of the bottom end?
Have we seen the piston pin and bearing?
What's the lower end looking like?
Anything amiss there?
I'd be wanting to know why the piston is dinged.
But some people think that I "sweat the small stuff" too much.
Thank you for your long post. Lots of stuff to think about.
1) sandpaper -should I use wet sandpaper with wd-40 or something like that, what grit? . Lacquer thinner, soap and hot water, - I will be following your advice on that. Is there any danger in using baking soda or detergent and leaving it overnight in that and some water? Probably not good Idea , just throwing it out there
2) vacuum test - that's after reassembly right?
3) I buy ethanol free gas from the gas station and add stihl 2cycle engine oil to it , I use stihl's smaller cans to make sure I add right amount , I'm pretty sure it's 1:50 I buy the better stihl oil. and you know what I will have to go back to my receipts and see when I purchased the saw , something in my memory is telling me that they gave me 2 more years of warranty because I bought a bunch of that better quality oil from them
4) you mention - rich mode, but this is the way it was set when I bought it, do they not set the carb when selling?
5) spark plug only came loose once , I usually tighten down pretty good, same with the nipple. thanks for the info though.
6) I was not asking how to clean my air cleaner - not sure where that came from , I was just mentioning the fact that the screen behind the air cleaner was dirty, but I cleaned it up
7) you mention "matching grooves " on a new piston - not sure what you mean. how deep are they ? what is the approximate distance from top of piston down to the groove? I don't see so much wear on the piston that an entire groove would be worn off and disappeared , maybe this is a recent change? if I knew how and what to do, I could ask my brother to put it into his lathe and just just ad a grove. I think I need to know more about that though.
8)piston to cyl wall measurement - is that done with micrometers? I do have both inside and outside micrometers, I could do that, or is there a different way its done?
9) wot - means with open throttle right? I was not running it for "nearly a month" WOT. I was milling a log with a tip of the bar as in one of youtube vids. and was running it at higher rpms(not constantly , but more than I should've) this job didn't take more than an hour. saw was running good after that. next day I was cutting a big maple and about half an hour or more into cutting , it started acting out. first the plug started working itself loose ...
This job is now on back burner, as I picked up four saws on offerUp for $100 mac 10-10, ms280,ms310, husky394xp. mac was complete, all other saws had missing bars and parts. on average it took about$90 aditional money into each saw to complete them. So this 394xp is a temporary substitute for ms660. Of course I will be finishing up the 660 project, just not in as much of a hurry now. I will be keeping you guys updated on the project. Thanks for your participation.
I think there's probably a whole lot of over thinking going on in this thread. First of all, an air leak or bad crank seal can in no way make your saw run like that. Clean the topend and put it back together. Don't sand anything unless you just want to remove the carbon from the piston crown. Forget measuring anything. Your topend is fine. I also would not call that rich. If anything it's running hot and lean and baking the carbon on the crown and CC.
Verify the tank vent is good. Clean the carb. Trim the limiters on the carb needles and reinstall.
I really think it sounds like more of an ignition problem than anything else. Replace the plug and see if that does it.
Verify the tank vent is good. Clean the carb. Trim the limiters on the carb needles and reinstall.
I really think it sounds like more of an ignition problem than anything else. Replace the plug and see if that does it.
>I think there's probably a whole lot of over thinking going on in this thread.
I think there is probably a whole lot of too simplified thinking going on in this thread! we all know a too loose spark plug won't fire up any engine... or ensure an optimized performance parameter...
LegDeLimber
Addicted to ArboristSite
Oh It's definitely breaking up like a missfire. Seems to do it after about the second consecutive cut each time.
Have you tried another spark plug?
Id look the current one over for any damage, maybe a cracked insulator or fouling track down in the side of the tip, etc.
just to cover the bases, What about a close look at all of the wiring
any damage to the plug boot? Chaffing anywhere or losse wire bouncing and arcing?
But having said all of that.
I'd still want to find the reason for the pecker tracks on the piston top.
and with that all said, I'll go sit down and shaddup about it now.
Have you tried another spark plug?
Id look the current one over for any damage, maybe a cracked insulator or fouling track down in the side of the tip, etc.
just to cover the bases, What about a close look at all of the wiring
any damage to the plug boot? Chaffing anywhere or losse wire bouncing and arcing?
But having said all of that.
I'd still want to find the reason for the pecker tracks on the piston top.
and with that all said, I'll go sit down and shaddup about it now.
inbilya, - Thank you for your long post. Lots of stuff to think about.
> you are welcome. that is one heck of a nice saw!!
engine 'building' or issues interesting... yes lots of stuff to think about. interesting project to me, so I will share my thots... 2-cents, etc.
I listened to your vid twice now. don't sound like a plug to me. I cannot 2nd guess what it is, nor can I knock the experience nor comments of other posters... I find them interesting too. but I did hear it run what sounded to me as good, intitially. I did hear it get lazy... and I did hear it high rpm tween cuts. what I can say with conviction is what I would do next it if was mine. a) I would put a fresh sharpening on chain. b) and lube the pto end of crank, and the clutch needle bearing. if u cannot do that, I would want a new chain, but lube pto end of crank. take off start handle side and blow out clean etc... flywheel, mag etc. then I would like to hear it run. and cut, but... I also can tell you I would never buck a chunk as you are in that vid! log is on the ground, and ur chain is very close to ground. u noodle it then cookie it. I would never cut a log like that in that manner. I would support it first from underside... w/stix, etc. so the cut is free and the log does not put any bind on bar or chain. and chunk can fall free and away from the cut... or so as to not put any pressure on chain or bar. also, before I cut again, I would run the tip off ground so as to ensure bar being oiled. ie, ck spray/toss off pattern and I would inspect the bar to ensure its straight, clean in grooves and not making ridges on bar slot sides, etc. and if your clutch drum teeth show any appreciable wear, or mine... I would replace with new. if used chain, inspect to ensure no broken teeth or missing. wear gloves. c) if mine, once reassembled I would run chain a bit looser. I like guide teeth depth 1/2. for this I would run it 3/4 loose in middle of bar. or thereabouts. for initial testing. I would be taking it easy on saw once back together at first. maybe couple tankfulls. if mine, I would not be putting it back to milling... 'rite of of the overhaul box!'
as suggested, get a new spark plug. it cannot hurt. install it correctly, ensure gap is correct, cyl head threads clean... and use small dab 1/8th or so of anti-seize on each side of the plug. i install with toothpick and smear it for good coating. hand tighten. it should go to washer most of the way, use wrench to set, then use a torque wrench to set its torque setting. not real good and tight. torque it to spec! do it! that and the above will ensure you have no friction issues that are fighting against you... my saws always run crisper and faster, work better serviced as above. this then lets us address more of the lots of stuff to think about, especially since u have it apart.
1) sandpaper -should I use wet sandpaper with wd-40 or something like that, what grit? . Lacquer thinner, soap and hot water, - I will be following your advice on that. Is there any danger in using baking soda or detergent and leaving it overnight in that and some water? Probably not good Idea , just throwing it out there
> sandpaper. pistons and rings like nice round, clean oily cylinders. I would not hesitate to run some 600 grit w/dry paper longitudinally using gasoline only as a cutting agent. lightly, just to scrub things up. not to hone! this assumes for next run, same rings. if it was mine and I did scrub cyl once precleaned or carbon and any grits in there, they will all have them... once taken apart... I would not have a problem lightly running the 600 across the face of the rings. I said lightly... and not to remove metal, merely to lightly upset them a skosh. remember, this is my approach, not joes toms or bills, lol who are they? I am an engine builder. with a lot of experience. but I am not a chainsaw engine builder, but I am a tuner, too. i have a lot of dif 2-stroke engine/tuning exp. and I am a very expd porting and carb modifier, too. no -wd40! no baking soda... no need for next run to leave over nite. don't soak it, clean it! and 100% perfectly clean. it must be clean. a good engine builder will open a block of all fittings once machine work completed, air blow thoroughly... maybe vat it... briefly then wash every thing with hot boiling soapy water... to both clean and further degrease... uses spl brushed and spl bore brush... then once done, out side to hose and under water pressure blasts every thing hard. maybe does it all again, too... then once washed with water... air blows it and then uses rosebud on welder and heat soaks entire block to remove any and all moisture... now block is ready for pre-assembly prep and into clean room it goes... well, ideally. in any event u must get it clean, plain and simple. problem areas are in transfers. no junk there! it goes without saying nothing in crankcase, too. -0-!
2) vacuum test - that's after reassembly right? yes
3) I buy ethanol free gas from the gas station and add stihl 2cycle engine oil to it , I use stihl's smaller cans to make sure I add right amount , I'm pretty sure it's 1:50 I buy the better stihl oil. and you know what I will have to go back to my receipts and see when I purchased the saw , something in my memory is telling me that they gave me 2 more years of warranty because I bought a bunch of that better quality oil from them
> well for starters here. I would not run that stuff! I would go buy the canned premixed fuel that is avail these days. about $5 a can, 32 oz or so... expensive, but then very good fresh stabilized pre-mix. if this was my project, I would do as I do do... I buy it by the case, online. I use it straight, mixed, before reg premix and usually after if I am putting it into storage. good stuff, just don't try to compare it cost wise with pump gas... lol. you can be sure if this was mine I would not premix my own fuel until running correctly. in any event, I often filter my fuels into my saws, weedsters, etc 2 and 3 times... I have a very small micron filter... and even what it catches straight out of the pump is startling... water, black crud, etc... sometimes I will simply dump all the fuel out of my saw... into container... and refilter it... again! believe it! u can never have too clean of fuel, but ez to have dirty fuel... fuel filter or no fuel filter!!! I even filter my bar oil if it has been used and removed... but it sure runs slow... lol
know for sure, exactly what ur gasoline to oil ratio is! there are formulas... like 2.4 oz to 1 gallon = 50:1. use the stihl low ash. no less than med grade gasoline... and if it was mine, I would run it at 40:1 for a few tankfuls. look up and follow donnyboy's break in on utube for the 360 or 331 he did bearings n rings on. he does not reassemble and go cut cords of wood... ps: it is not 1:50, it is 50:1. I am not joking around, the info u need is there online, and best u know it, etc. engine building does not leave too much room for mistakes!
4) you mention - rich mode, but this is the way it was set when I bought it, do they not set the carb when selling?
> yes, but things change. a stihl dealer is supposed to be willing to ck ur settings if u bring saw in, per dealership agreement. some will others wont. but running a 660 u should be able to do it ur self. its easy. and start up is in ur operators manual for LA, H L as u have or have not. do not buzz the saw after start up, let it heat soak fully first, then bring up easily... you will want it to start up rich, or where ur manual tells u. like for L 1 turn to L or for H 1 1/4 turns to L, more to richen, to R to lean...
5) spark plug only came loose once , I usually tighten down pretty good, same with the nipple. thanks for the info though. ok, but usually isn't good enuff with engines. torque to proper specs! don't usually, just do it. takes a torque wrench! 3/8ths " drive in/lb click click-type is ideal for plugs.
6) I was not asking how to clean my air cleaner - not sure where that came from , I was just mentioning the fact that the screen behind the air cleaner was dirty, but I cleaned it up
post # 22 you sed: I know someone is gong to say something about those carbon deposits, I know I should've cleaned my air filter more often, but is that the only thing that effects that? and how do I safely clean it out?
so need I say more?
7) you mention "matching grooves " on a new piston - not sure what you mean. how deep are they ? what is the approximate distance from top of piston down to the groove? I don't see so much wear on the piston that an entire groove would be worn off and disappeared , maybe this is a recent change? if I knew how and what to do, I could ask my brother to put it into his lathe and just just ad a grove. I think I need to know more about that though. (see next post)
> you are welcome. that is one heck of a nice saw!!
engine 'building' or issues interesting... yes lots of stuff to think about. interesting project to me, so I will share my thots... 2-cents, etc.
I listened to your vid twice now. don't sound like a plug to me. I cannot 2nd guess what it is, nor can I knock the experience nor comments of other posters... I find them interesting too. but I did hear it run what sounded to me as good, intitially. I did hear it get lazy... and I did hear it high rpm tween cuts. what I can say with conviction is what I would do next it if was mine. a) I would put a fresh sharpening on chain. b) and lube the pto end of crank, and the clutch needle bearing. if u cannot do that, I would want a new chain, but lube pto end of crank. take off start handle side and blow out clean etc... flywheel, mag etc. then I would like to hear it run. and cut, but... I also can tell you I would never buck a chunk as you are in that vid! log is on the ground, and ur chain is very close to ground. u noodle it then cookie it. I would never cut a log like that in that manner. I would support it first from underside... w/stix, etc. so the cut is free and the log does not put any bind on bar or chain. and chunk can fall free and away from the cut... or so as to not put any pressure on chain or bar. also, before I cut again, I would run the tip off ground so as to ensure bar being oiled. ie, ck spray/toss off pattern and I would inspect the bar to ensure its straight, clean in grooves and not making ridges on bar slot sides, etc. and if your clutch drum teeth show any appreciable wear, or mine... I would replace with new. if used chain, inspect to ensure no broken teeth or missing. wear gloves. c) if mine, once reassembled I would run chain a bit looser. I like guide teeth depth 1/2. for this I would run it 3/4 loose in middle of bar. or thereabouts. for initial testing. I would be taking it easy on saw once back together at first. maybe couple tankfulls. if mine, I would not be putting it back to milling... 'rite of of the overhaul box!'
as suggested, get a new spark plug. it cannot hurt. install it correctly, ensure gap is correct, cyl head threads clean... and use small dab 1/8th or so of anti-seize on each side of the plug. i install with toothpick and smear it for good coating. hand tighten. it should go to washer most of the way, use wrench to set, then use a torque wrench to set its torque setting. not real good and tight. torque it to spec! do it!
that and the above will ensure you have no friction issues that are fighting against you... my saws always run crisper and faster, work better serviced as above. this then lets us address more of the lots of stuff to think about, especially since u have it apart. 1) sandpaper -should I use wet sandpaper with wd-40 or something like that, what grit? . Lacquer thinner, soap and hot water, - I will be following your advice on that. Is there any danger in using baking soda or detergent and leaving it overnight in that and some water? Probably not good Idea , just throwing it out there
> sandpaper. pistons and rings like nice round, clean oily cylinders. I would not hesitate to run some 600 grit w/dry paper longitudinally using gasoline only as a cutting agent. lightly, just to scrub things up. not to hone! this assumes for next run, same rings. if it was mine and I did scrub cyl once precleaned or carbon and any grits in there, they will all have them... once taken apart... I would not have a problem lightly running the 600 across the face of the rings. I said lightly... and not to remove metal, merely to lightly upset them a skosh. remember, this is my approach, not joes toms or bills, lol who are they? I am an engine builder. with a lot of experience. but I am not a chainsaw engine builder, but I am a tuner, too. i have a lot of dif 2-stroke engine/tuning exp. and I am a very expd porting and carb modifier, too. no -wd40! no baking soda... no need for next run to leave over nite. don't soak it, clean it! and 100% perfectly clean. it must be clean. a good engine builder will open a block of all fittings once machine work completed, air blow thoroughly... maybe vat it... briefly then wash every thing with hot boiling soapy water... to both clean and further degrease... uses spl brushed and spl bore brush... then once done, out side to hose and under water pressure blasts every thing hard. maybe does it all again, too... then once washed with water... air blows it and then uses rosebud on welder and heat soaks entire block to remove any and all moisture... now block is ready for pre-assembly prep and into clean room it goes... well, ideally. in any event u must get it clean, plain and simple. problem areas are in transfers. no junk there! it goes without saying nothing in crankcase, too. -0-!
2) vacuum test - that's after reassembly right? yes
3) I buy ethanol free gas from the gas station and add stihl 2cycle engine oil to it , I use stihl's smaller cans to make sure I add right amount , I'm pretty sure it's 1:50 I buy the better stihl oil. and you know what I will have to go back to my receipts and see when I purchased the saw , something in my memory is telling me that they gave me 2 more years of warranty because I bought a bunch of that better quality oil from them
> well for starters here. I would not run that stuff! I would go buy the canned premixed fuel that is avail these days. about $5 a can, 32 oz or so... expensive, but then very good fresh stabilized pre-mix. if this was my project, I would do as I do do... I buy it by the case, online. I use it straight, mixed, before reg premix and usually after if I am putting it into storage. good stuff, just don't try to compare it cost wise with pump gas... lol. you can be sure if this was mine I would not premix my own fuel until running correctly. in any event, I often filter my fuels into my saws, weedsters, etc 2 and 3 times... I have a very small micron filter... and even what it catches straight out of the pump is startling... water, black crud, etc... sometimes I will simply dump all the fuel out of my saw... into container... and refilter it... again! believe it! u can never have too clean of fuel, but ez to have dirty fuel... fuel filter or no fuel filter!!! I even filter my bar oil if it has been used and removed... but it sure runs slow... lol
know for sure, exactly what ur gasoline to oil ratio is! there are formulas... like 2.4 oz to 1 gallon = 50:1. use the stihl low ash. no less than med grade gasoline... and if it was mine, I would run it at 40:1 for a few tankfuls. look up and follow donnyboy's break in on utube for the 360 or 331 he did bearings n rings on. he does not reassemble and go cut cords of wood... ps: it is not 1:50, it is 50:1. I am not joking around, the info u need is there online, and best u know it, etc. engine building does not leave too much room for mistakes!
4) you mention - rich mode, but this is the way it was set when I bought it, do they not set the carb when selling?
> yes, but things change. a stihl dealer is supposed to be willing to ck ur settings if u bring saw in, per dealership agreement. some will others wont. but running a 660 u should be able to do it ur self. its easy. and start up is in ur operators manual for LA, H L as u have or have not. do not buzz the saw after start up, let it heat soak fully first, then bring up easily... you will want it to start up rich, or where ur manual tells u. like for L 1 turn to L or for H 1 1/4 turns to L, more to richen, to R to lean...
5) spark plug only came loose once , I usually tighten down pretty good, same with the nipple. thanks for the info though. ok, but usually isn't good enuff with engines. torque to proper specs! don't usually, just do it. takes a torque wrench! 3/8ths " drive in/lb click click-type is ideal for plugs.
6) I was not asking how to clean my air cleaner - not sure where that came from , I was just mentioning the fact that the screen behind the air cleaner was dirty, but I cleaned it up
post # 22 you sed: I know someone is gong to say something about those carbon deposits, I know I should've cleaned my air filter more often, but is that the only thing that effects that? and how do I safely clean it out?
so need I say more?
7) you mention "matching grooves " on a new piston - not sure what you mean. how deep are they ? what is the approximate distance from top of piston down to the groove? I don't see so much wear on the piston that an entire groove would be worn off and disappeared , maybe this is a recent change? if I knew how and what to do, I could ask my brother to put it into his lathe and just just ad a grove. I think I need to know more about that though. (see next post)
continuing:
no, I said machining grooves, standard on all general use pistons. reduces friction, helps cool and hold oil to sides of piston skirts and on face of bore. they are not deep at all prob .002 maybe even less. don't worry about top of piston to first groove. of no consequence here other than wear. u have some wear. but while to me ur saws shows heavy use, it is all still in serviceable condition for ur pictorial subject to something else coming out of the wood pile. do not try to add grooved or modify! simple do not! its not ur problem for running out of spec. just be sure piston and rings as clean as possible given u wont be removing rings. but in any event, and aside from these comment, ur saw will have to make proper compression to run strong! new rings r better than older heated and well used rings. just know that. but ur saw may be down on power, but should run in that tune consistently... not off and on again...
8) piston to cyl wall measurement - is that done with micrometers? I do have both inside and outside micrometers, I could do that, or is there a different way its done?
measuring, micrometers... could be, but doubtful. piston to bore running clearances are normally measure with a feeler gauge, albeit for engine work a long one. again, I think your mechanicals look ok for rationalization to button it up and try it again. more compression, ie new rings mite make it crisper... since u want to run it again, ur wear is fixed. just be sure everything clean and small end rod/bearing/pin oiled well and correctly for reassembly, as piston to bore. use a ring compressor! $9 most shops... the orange ones.
9) wot - means with open throttle right? I was not running it for "nearly a month" WOT. I was milling a log with a tip of the bar as in one of youtube vids. and was running it at higher rpms(not constantly , but more than I should've) this job didn't take more than an hour. saw was running good after that. next day I was cutting a big maple and about half an hour or more into cutting , it started acting out. first the plug started working itself loose ... WOT - yes. well, u said 150 hours running time and how can u cut if not wot? or thereabouts? u sed: and was running it at higher rpms(not constantly , but more than I should've) to me? I read: abuse! imo, ur saw shows being run hot and for long periods of time. maybe with dull chain, too! not well maintained for a milling saw application... I am confused plug works loose! I have never seen a properly installed and torqued plug back out! ever ! there is the issue of damage to the piston crown... its on going or has passed thru. in any event that of itself to me is not ur problem...
to use to advantage all of these comments from me and others, ur saw much be reassembled properly. then u can address the variables, like pto lube/service... clutch innards get stuffed with oil and saw dust... to throttle up I would do it easily. no blipping! run it just under LA setting. or, if careful just past. (chain will rotate) once fully warmed up, and u know all in fuel tank and vent free, open and new fuel filter, no fuel line to carb probs, new air cleaner, etc... rpm it easily... does it spool up smoothly? if real crisp may be bit lean. if lazy or intermittent may be too rich. adjust accordingly. you said u would ck carb after trying to run it again.
service the carb now. easy to do. ensure no dirt, sawdust inside. get new kit. u get pulse pump diaphragm, metering valve diaphragm, float setting etc... or if u don't care to, buy and install a new carb. rebuild urs later for a spare... you could have an issue with fuel delivery signal and strength. small holes in a carb... any one plugged and that's it. no workie well! before u tear into it, study the online info on rebuilding chain saw carbs, ur type. there is plenty of info to help u. pick 2 guys that show u urs and follow their advice. Donnyboy does a good job. its a simple do, but must be done methodically... and all parts that come apart, go back exactly same way. but lots of step by step info online u tube.
you can prob contact a chain saw dealer; stihl and ask for a vac check out price? or just give it a 2nd try. it was running. and it did peak!, too. so it hit close to or top rpms... 135oo or so. successful engine building is directly related to how the builder controls all the variables... control them all to spec, she will run perfectly every time... deviate and u get what u get...
hope this helps. I don't mind thinking it thru with u, makes me think of my 044 project, too. I am dealing with many of the same things u r... as soon will be reassemblying mine also. if u get back to it, let us know how it goes... good luck!
This job is now on back burner, as I picked up four saws on offerUp for $100 mac 10-10, ms280,ms310, husky394xp. mac was complete, all other saws had missing bars and parts. on average it took about$90 aditional money into each saw to complete them. So this 394xp is a temporary substitute for ms660. Of course I will be finishing up the 660 project, just not in as much of a hurry now. I will be keeping you guys updated on the project. Thanks for your participation.
no, I said machining grooves, standard on all general use pistons. reduces friction, helps cool and hold oil to sides of piston skirts and on face of bore. they are not deep at all prob .002 maybe even less. don't worry about top of piston to first groove. of no consequence here other than wear. u have some wear. but while to me ur saws shows heavy use, it is all still in serviceable condition for ur pictorial subject to something else coming out of the wood pile. do not try to add grooved or modify! simple do not! its not ur problem for running out of spec. just be sure piston and rings as clean as possible given u wont be removing rings. but in any event, and aside from these comment, ur saw will have to make proper compression to run strong! new rings r better than older heated and well used rings. just know that. but ur saw may be down on power, but should run in that tune consistently... not off and on again...
8) piston to cyl wall measurement - is that done with micrometers? I do have both inside and outside micrometers, I could do that, or is there a different way its done?
measuring, micrometers... could be, but doubtful. piston to bore running clearances are normally measure with a feeler gauge, albeit for engine work a long one. again, I think your mechanicals look ok for rationalization to button it up and try it again. more compression, ie new rings mite make it crisper... since u want to run it again, ur wear is fixed. just be sure everything clean and small end rod/bearing/pin oiled well and correctly for reassembly, as piston to bore. use a ring compressor! $9 most shops... the orange ones.
9) wot - means with open throttle right? I was not running it for "nearly a month" WOT. I was milling a log with a tip of the bar as in one of youtube vids. and was running it at higher rpms(not constantly , but more than I should've) this job didn't take more than an hour. saw was running good after that. next day I was cutting a big maple and about half an hour or more into cutting , it started acting out. first the plug started working itself loose ... WOT - yes. well, u said 150 hours running time and how can u cut if not wot? or thereabouts? u sed: and was running it at higher rpms(not constantly , but more than I should've) to me? I read: abuse! imo, ur saw shows being run hot and for long periods of time. maybe with dull chain, too! not well maintained for a milling saw application... I am confused plug works loose! I have never seen a properly installed and torqued plug back out! ever ! there is the issue of damage to the piston crown... its on going or has passed thru. in any event that of itself to me is not ur problem...
to use to advantage all of these comments from me and others, ur saw much be reassembled properly. then u can address the variables, like pto lube/service... clutch innards get stuffed with oil and saw dust... to throttle up I would do it easily. no blipping! run it just under LA setting. or, if careful just past. (chain will rotate) once fully warmed up, and u know all in fuel tank and vent free, open and new fuel filter, no fuel line to carb probs, new air cleaner, etc... rpm it easily... does it spool up smoothly? if real crisp may be bit lean. if lazy or intermittent may be too rich. adjust accordingly. you said u would ck carb after trying to run it again.
service the carb now. easy to do. ensure no dirt, sawdust inside. get new kit. u get pulse pump diaphragm, metering valve diaphragm, float setting etc... or if u don't care to, buy and install a new carb. rebuild urs later for a spare... you could have an issue with fuel delivery signal and strength. small holes in a carb... any one plugged and that's it. no workie well! before u tear into it, study the online info on rebuilding chain saw carbs, ur type. there is plenty of info to help u. pick 2 guys that show u urs and follow their advice. Donnyboy does a good job. its a simple do, but must be done methodically... and all parts that come apart, go back exactly same way. but lots of step by step info online u tube.
you can prob contact a chain saw dealer; stihl and ask for a vac check out price? or just give it a 2nd try. it was running. and it did peak!, too. so it hit close to or top rpms... 135oo or so. successful engine building is directly related to how the builder controls all the variables... control them all to spec, she will run perfectly every time... deviate and u get what u get...
hope this helps. I don't mind thinking it thru with u, makes me think of my 044 project, too. I am dealing with many of the same things u r... as soon will be reassemblying mine also. if u get back to it, let us know how it goes... good luck!
This job is now on back burner, as I picked up four saws on offerUp for $100 mac 10-10, ms280,ms310, husky394xp. mac was complete, all other saws had missing bars and parts. on average it took about$90 aditional money into each saw to complete them. So this 394xp is a temporary substitute for ms660. Of course I will be finishing up the 660 project, just not in as much of a hurry now. I will be keeping you guys updated on the project. Thanks for your participation.
There, I fixed your first sentence for ya.
There really is too much over thinking going on IMO.I use to have a 4 wheeler that had stripped spark plug threads. Before it got fixed we would ride the snot out of it with the spark plug finger tight.
I honestly feel sorry for this guy. He comes in here asking for help and instead gets led on a goose chase causing him to believe his saw is junk. Misinformation is worse than no information.There, I fixed your first sentence for ya.
Don't take this personal but I feel the need to interject some sense here. There isn't a damn thing wrong with that piston or that cylinder, I still see the machine marks in the piston in the pictures and there is no transfer on the cylinder walls. Second of all, its never a good idea to scuff the piston rings with an abrasive... period.
@inbilya, put the sandpaper down and step away from the bad advice. Pick up a can of Brake Kleen, spray the piston and rings off, let dry (compressed air helps), add a drop or two of fresh 2-stroke oil and lightly coat the piston skirt and assemble. Clean the cylinder walls with a lint free rag and a couple shots of cleaner. Lightly oil and reassemble. If you would like to clean up the piston top some you can take a brass wire brush and some of the Brake Kleen to it but its probably not worth the effort.
Get the saw back together and check that the issue is still present before you do anything more. You don't want to introduce any more variables.
A dirty air filter does not effect carbon deposits in any way. Oil quality, gas quality, ratio of each, air to fuel ratio, combustion temperatures are all things that affect carbon build-up. The dirty air filter could explain the whisker marks above the top ring and the edge of the piston dome on the exhaust side.
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