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Piston cleanup...how much is too much?

Discussion in 'Chainsaws' started by Frank bierce, Nov 10, 2017.

  1. Frank bierce

    Frank bierce Here For The Long Haul!

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    Have seen some members talk about cleaning up their scored/lightly scored pistons, and running them with new rings. I have personally pitched a good portion of the pistons if they show signs of scoring.
    Anyone have any before, and after photos of ones they have cleaned up?
    In these couple lots of saws I have purchased recently, I am finding quite a few jugs and pistons that have light scoring/transfer. Some are on some older saws, that are harder to get parts for.
    I’d generally just pitch the pistons, but if they may be salvageable...why not!!
    Thanks for any input fellas!!
     
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  2. Stihlsmoking

    Stihlsmoking City Hillbilly

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    I'd like to see some also I have one I cleaned up but kinda scared to put together and run in fear of ruining a good cylinder ?
     
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  3. Frank bierce

    Frank bierce Here For The Long Haul!

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    I haven’t cleaned any up “yet”, but fear the same thing.
     
  4. Stihlsmoking

    Stihlsmoking City Hillbilly

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    This is what I did but thinking about just getting new or meteor instead of running?
    Sorry don't have before pics. Exhaust
    IMG_5988.JPG
    Intake side.
    IMG_5987.JPG
    I'm sure someone that's done it will chime in soon ?
     
  5. breese

    breese Pinnacle OPE Member

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    Here is what I have done to my 59 year old Homelite EZ.
    Went for the best polish job I could get without (hopefully) affecting the coating.

    Piston Orig 01.JPG Piston Orig 02.JPG
    Piston Unpolished.JPG Piston Polish.JPG
     
  6. Wilhelm

    Wilhelm Here For The Long Haul!

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    I should have some before and after pictures of my Sachs-Dolmar 105 piston on my desktop PC.

    Will take a look and post if I find them.
     
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  7. old guy

    old guy Love me some Husqvarna

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    I would certainly run that piston.
     
  8. cus_deluxe

    cus_deluxe ONE OF THE WORST!!

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  9. Jon1212

    Jon1212 Birch! Please.....

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  10. blsnelling

    blsnelling Friend of the Riff Raff

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  11. Frank bierce

    Frank bierce Here For The Long Haul!

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    Any rule of thumb on excessive clearance? What would be considered excessive?
     
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  12. heimannm

    heimannm Pinnacle OPE Member

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    Looking at a number of pistons/cylinders in the McCulloch literature, seems 0.004" at the skirt is pretty normal. Piston top is generally smaller by a 0.002" so more like 0.006" at the piston top.

    This is from older saws for what it's worth.

    Mark
     
  13. Cracker Boy

    Cracker Boy Fl cracker

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    Id run the chit out of it and not think twice.i will take any one you dont wanna run like that if your gonna pitch it.
     
  14. drf256

    drf256 Dr. Richard Cranium (“RC” to Muh pals)

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    That ends in Y

    Like Brad said, it’s the clearance that matters more than the scuffs. Won’t ruin a cylinder.

    They tend to wear on the intake skirt. Then they slap and the skirt breaks there.

    Measure the intake skirt thickness with your calipers and against the Ex side skirt and a known good piston. If you don’t have a new piston to measure, text me tonight and I’ll measure one if I’ve got the model here.

    Usually the clearance is .002-003 at the skirt. So slide it up the bore and see if there is resistance to a .002-3 feeler gauge being slid up into it. If a .002 fits snugly and a .003 won’t, you’re good Jeremy.
     
  15. Al Smith

    Al Smith Pinnacle OPE Member

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    If memory serves I think the max allowed under size or excentricity according to McCulloch is 5 thou in addition to a 4 thou normal clearance .
    When I resleeved a Mac 125 some time ago I honed it for around 4.5 thou fit .Even that long ago I still haven't ran that saw enough to seat the rings .I haven't even started it for 5--6 years
     
  16. Wilhelm

    Wilhelm Here For The Long Haul!

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    1985. Sachs-Dolmar 105, first ever disassembly in 2015.
    Engine was actually running OK, but clutch weigh broke and I noticed the amount of blow by through the exhaust port so I took her apart to replace the single ring and clean up the blow by and carbon scoring.
    Before:
    IMAG0075.jpg

    After:
    IMAG0115.jpg IMAG0116.jpg IMAG0117.jpg IMAG0118.jpg

    This little 40cc magnesium body saw has endured WOT passages in large sized dry hardwood (locust) tank full after tank full.
    Operator (me) was completely oblivious regarding chain sharpness, the 3/8" LowProfile 52DL loops were wearing through the tie straps and break while the teeth would still have at least half their length.
    The diet this saw was exposed to is gruesome, regular engine oil mixed into gasoline without any measuring tool other than the "rule of thumb" - generally if the saw didn't smoke too much I would ad more oil into the mix till she did.
    When used this saw would get boiling hot and stay that way all day long.
    During fuel refills the fuel would foam and immediately start boiling within this saws little belly - I'd just quickly screw the tank cap back on, start the saw and keep grinding metal (chain against bar rails) and making fine saw dust.

    I'm not proud of the above.
    My poor excuse is that there was no one to show/teach me better.
     
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  17. riverrat2

    riverrat2 Semper Fidelis

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    Nice job!!!! I would not be scared to run it!!!!!

    That clean up with a fresh ring would make a runner I'm thinking,,,,

    and with modern fuels either pre-mixed or good synthetic oil mixed @ 40:1 and sharp chains it should go another good long while!!!
     
    Last edited: Nov 12, 2017
  18. riverrat2

    riverrat2 Semper Fidelis

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    Good on you Mark, Thanks for posting, and good to see you posting and contributing as usual!!!!
     
  19. I Know Something

    I Know Something Super OPE Member

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    I'm going to assume a Scotchbight pad is all you need then? Is there a difference between the red and green one in abrasiveness?
     
  20. Junk Meister

    Junk Meister Super OPE Member

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    I "THINK" the red is more aggressive. I have seen different texture/weave and am watching this thread for more great information.
     
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