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best way to break in a newly rebuilt saw

Discussion in 'Chainsaw' started by NZ dave, Apr 13, 2019.

  1. NZ dave

    NZ dave ArboristSite Lurker

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    Got a Husky 365 special that's got a dead cylinder and piston (deep scratch in cylinder).

    I've purchased a meteor piston and cylinder plus piston bearing and caskets so i can get the saw up and running again.

    Question is what ratio to use?

    Looked at these postings and i have usually used 40:1 using 91 octane (Note I'm in chch NZ) the saw was hard to start with when i brought it 2nd hand and was only late last year that it wouldn't start and keep running at all....
    https://www.arboristsite.com/community/threads/best-way-to-break-in-a-never-been-started-saw.211498/

    Also should i put some mix into the base of the saw so the lower bearings get a splash of oil n gas before putting cylinder on.

    Oh and other thoughts plz

    Look forward to you're thoughts.
     
  2. NSEric

    NSEric ArboristSite Operative

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    Use the same ratio you will run after the saws broken in.
    I run my saws a touch rich on the high for a couple tanks before tuning them to rev like they should. ie set it to max out at 12500 instead of 13500.
    I don't bother putting premix in the base as the saws I've worked on still had a oil film on the bearings from when they ran last but it wouldn't hurt anything.
     
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  3. holeycow

    holeycow Addicted to ArboristSite

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    I think it’s a good idea to try to get a wee bit of oil on the mains. You should flush the cases with premix by pumping the crank and draining a time or three. That should suffice for lube, especially if you’re at 20:1 or so for this flushing step.

    It’s imperative to lightly oil the piston ring/groove and the wrist-pin bearing. Use straight mix oil.

    I also apply (with a clean finger) a very light coat of oil on the cylinder wall. Some like the cylinder dry with either no oil or a tiny wisp of oil in the ring groove..

    Assemble and run a partial tank. Then re-torque all the disturbed fasteners to make sure everything is still tight.

    Since the bottom end is already broke in being a used saw, run it like you stole it in a limbing application for 10 minutes or so and then bury it for a few cuts (tuned a little rich as mentioned) Break-in complete. Check your bolts, retune and enjoy!

    Oh, and run 40:1 or so..:chainsaw:

    Some may disagree on all of this. Lol.
     
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  4. Whiskers

    Whiskers Addicted to ArboristSite

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    Use it
     
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  5. Duce

    Duce Addicted to ArboristSite

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    You can put straight 2 stroke oil on wrist pin bearing, rod bearing, case bearing and coat cylinder before assembly. I always do, it smokes a little more at start up, but clears right up. Run it a little fat for a tank and then run it. Everyone has a plan.
     
  6. Northerner

    Northerner ArboristSite Operative

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    Exactly what I do
     
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  7. Brent Nowell

    Brent Nowell ArboristSite Operative

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    All three of my saws I used 40:1 good mix and ran the piss out of em till the tank was empty. Pretty much cutting cookies for two tanks. It’s been almost a year and pistons look great through the exhaust port.
    This issue has been covered so many times here by searching, everyone has their own way of doing it. In the end, modern oil mixed with non ethanol gas, a good condition saw with no air leaks, and a sharp chain, there’s no wrong way to breaking it in than that.
     
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  8. Broken

    Broken ArboristSite Operative

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    Like any 2 or 4 cycle vary the rpm and load during break in to vary the heat cycles . In saws normally a tank of fuel is sufficient to run in the rings and bore .
     
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  9. catbuster

    catbuster Catskinner. And buster.

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    I use a new saw like I would any other chainsaw. I have two throttle positions: WFO or idle. Beyond that, I run a good oil with a good gasoline and just run it, haven’t had any premature failures yet.
     
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  10. vhmtach38

    vhmtach38 ArboristSite Member

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    I’ve heard that after the initial start up...let your saw idle for about 30 minutes...(rich mixture) then go from there...it ought to gain compression after 2 tankfuls of mix...Happy sawing..!!
     
  11. Huskybill

    Huskybill Addicted to ArboristSite

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    Having a chrome cylinder and chrome rings it takes a lot of time to fully break in.

    First when i assemble any two stroke before I put the cylinder on I give the crankcase wall above both crankbearings a shot of two stroke oil to pre lube them. I tilt the saw so the oil runs down into the bearing. I burnish a moly paste or anti seeze into the cylinder walls and piston skirt I pre lube the rod ends, piston skirt and cylinder with oil and assemble. I run my mix a tad oil rich anyway I’m under 40:1. I start it up let it idle so the crankcase gets fogged with oil. Then let it warm up, adjust the carb low speed and idle then rev it up to adjust the high speed.

    TS-70 moly, www.tsmoly.com

    Moly is that grey engine assembly lube it comes with cam shaft kits too. It eliminates all wear, reduces friction, prevents galling, fights corrosion and doesn’t attract dirt.
    I use moly in lubing everything. I use moly grease too.
     
  12. NZ dave

    NZ dave ArboristSite Lurker

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    Been a while and have been unable to get back on till now,
    Thanks for all the comments, They all sorta repeat what was said on the other forum URL i put up so thanks all n hope this posting helps others in future with regards to
    fitting a new cylinder/piston to a saw.
     

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