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How to prep used cylinder for new piston.

Discussion in 'Chainsaw' started by MrGiggles, Sep 5, 2009.

  1. MrGiggles

    MrGiggles ArboristSite Operative

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    I recieved a piston for my Husky 55 today and am going to replace the old one because it was ran lean. Piston is shot but the cylinder is only very lightly scored. How should I prep the cylinder for the new piston and rings? Or do I even have to?
     
  2. dragrcr

    dragrcr Addicted to ArboristSite

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    use caustic soda to get the aluminum off the cyl, put the rings on the piston and insert. maybe a VERY VERY light hone.
     
  3. MrGiggles

    MrGiggles ArboristSite Operative

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    Is that the only way to do it? I don't have any of that. Maybe a light sanding with 400 grit?
     
  4. Steve K

    Steve K ArboristSite Operative

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    Most of the time the scoring that you feel is aluminum transfer from the piston. I use muriatic acid to remove the aluminum from the cylinder wall. I apply it with a Qtip only to the area that is scored and let it sit for a few minutes. Then rinse it with a spray bottle of warm soapy water. Wet sand with 340 grit and re-apply the acid if needed, sometimes it takes 3 or 4 attempts to get it all removed. Some folks here have had success with oven cleaner as it will eat aluminum also but muriatic acid can be had pretty easy. I buy mine at my local Ace Hardware as it's used for cleaning concrete, etc.
     
  5. MrGiggles

    MrGiggles ArboristSite Operative

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    I'm sure there isn't any place around here where I can get acid but I know I can get oven cleaner. I will probably go that route.
     
  6. ODS9091

    ODS9091 ArboristSite Lurker

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    You should be able to get it at Lowe's. i had a friend that had a pressure washing business, he used it to clean concrete as well, and this is where he would get it.
     
  7. MrGiggles

    MrGiggles ArboristSite Operative

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    My nearest Lowes is an hour away. I probably won't make it up there again for a couple weeks.

    I just happened to have a new can of Oven Cleaner under the sink. Will any old kind work? Do I just spray it, let it sit, rinse and sand?
     
  8. rms61moparman

    rms61moparman Addicted to ArboristSite

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    Try a scotchbrite pad and some laundry detergent.....lightly!
     
  9. tdi-rick

    tdi-rick Addicted to ArboristSite

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    Any Hardware store should stock hydrochloric acid/HCl (muriatic acid in the US)
    They all do here.

    Don't spray anything caustic or acidic around if you want the rest of the cylinder to stay as is, as Steve said use a cotton bud where it's needed.
    I wouldn't hone either, Nikasil and chrome cylinders need specific stones, all you'll do with the common type ball hone is knock the top off the already honed surface and you stand a good chance at buggering the oil retaining ability of it.
     
  10. MrGiggles

    MrGiggles ArboristSite Operative

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    Local hardware store is already closed till Tues.

    I'm using cotton swabs with the oven cleaner right now. We'll see what happens.
     
  11. 046

    046 Addicted to ArboristSite

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    don't use muriatic acid anywhere close to aluminum. it will destroy aluminum in a hurry. muriatic acid is gentle on steel and will take off rust nicely. but will destroy aluminum.

     
  12. eyolf

    eyolf Addicted to ArboristSite

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    The hardware stores all carry the muriatic acid in my area. If you're in a farming area, milkstone cleaner for milking machines contains phosphoric acid and will work. Even battery acid will work, and knowing that you'll only need a couple of Q-tips full, maybe you could just get some from an older battery with removable caps.

    Be careful with muriatic acid: do the cleaning outside if you can, and close the cap very tightly on the jug. I learned the hard way by fumes escaping and causing rust on a few tools hanging on the pegboard above the workbench...not a real huge problem, I guess, but I used the milkstone solvent last time. Its a little slower, but works.

    I'de say that using a basic solution would probably be a pain...too slow, unless you had something like pure lye. And that would be kinda dangerous.

    Modern two-strokes with Nikasyl bores can be reassembled without honing. Honing creates microscopic scratches that trap oil and makes seating the new rings happen faster. But the coating is so hard that a brake-cylinder hone (that most of us would try to use) is nearly useless. It may take a little longer to wear the rings in the second time around, but that isn't a big problem.

    I stuck (very lightly) my Husky 395 about a month ago: a just reassembled it after cleaning the psiton wipe from the cylinder. After siezing it had about 80PSI, right away after I put it back together it was about 135, hot. Still kinda low, but enough to finish a job. I have ran about 2 gallons through the saw since, and another 2 gallons today and its up to about 155 PSI hot.

    Kinda funny: I seldom need that saw, but when I siezed it I needed it bad, and have needed it several times since. I ordered a piston, but might not put it in: as soon as I do, I won't need to use it...and it's so much fun!
     
  13. Evan

    Evan Addicted to ArboristSite

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    yup ig you acidently get muratic acid in the exhaust port youl know it fast beacause itl start bubln, but dont worry about to much just rinse it off and reaplly

    i also use a q tip to apple.

    some times it takes much more then 3-8 attmpts to get all aluminum transfer removed. when in doubt do another coat of muratic then do light hone.

    if you dont get it all out then your basicaly ruining your new piston and in hurry.

    good luck
     
  14. kkesler

    kkesler ArboristSite Operative

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    Sorry to threadjack, but this is very timely as I about to put new rings in a MS390 (no scoring, just tired). Does the above advice apply?
     
  15. Evan

    Evan Addicted to ArboristSite

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    if there is no scoreing then there is no neeed to do anything, just clean it with soapy watter and blow it out before it goes back together.
     
  16. MrGiggles

    MrGiggles ArboristSite Operative

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    I used the oven cleaner and it helped, but there was still some visible scratches. I put in the new piston and ring and runs good. I will do some final tuning when I get a B&C on it. It also missing some screws, the metal clips that hold the top on, and other small pieces I will need before it gets used. Anyone know a good place for parts for these?
     
    Last edited: Sep 5, 2009
  17. tdi-rick

    tdi-rick Addicted to ArboristSite

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    Which is why you use it to remove aluminium piston pickup from the bore, and why i said not to spray it around. ;)
     
  18. tdi-rick

    tdi-rick Addicted to ArboristSite

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    From here http://www.electrosil.com.au/news1.htm
     
  19. 046

    046 Addicted to ArboristSite

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    why use muriatic acid at all?

     
  20. tdi-rick

    tdi-rick Addicted to ArboristSite

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    ?? You've lost me.

    The OP thought he had aluminium on the bore (piston pickup from running lean). Judicious use of hydrochloric acid on the Nikasil or chrome gets rid of it.
     

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