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Stihl 440 hop up.

Discussion in 'Chainsaw' started by SamT1, Dec 10, 2018.

  1. SamT1

    SamT1 ArboristSite Guru

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    So I returned from vacation to find my Chinese plastics and handle. While I have this saw apart I figured I’d do some upgrades to it.
    First thing I’m gonna do is clean it good and check the compression. What’s the compression range I want? If I remember 150 is good. What’s the best process for getting a good reading?

    For sure I’m gonna mod the muffler. I’m thinking drill a second exhaust hole beside the first (same size if there’s room to use the spark arrestor) and put a small piece of tube around them like a exhaust pipe to keep debris and rain out. Point it foreword Remove any baffles inside.

    If the compression is still good is there anything else minor to do to the engine? If it fails compression the sky is the limit I guess?

    I need some new felling dogs. I have a tooth broken off. I’d like a dual set that’s a little more aggressive than stock. Any suggestions?

    Anyone ever do any painting on a saw?

    Sam
     
  2. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    Is this an OEM piston and cylinder saw or an AM setup.? Compression will differ between the two.
     
  3. SamT1

    SamT1 ArboristSite Guru

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    It’s oem magnum.
     
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  4. Rick Stephens

    Rick Stephens ArboristSite Operative

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    I'll be interested to hear what is recommended. My 440 is getting long in the tooth and needs a disassembly and cleaning. It has a MM that made a big difference. I should re-ring it, since compression is down to 130. Otherwise still a great saw. Should be a fun thread.

    Rick
     
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  5. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    On OEM sets you would need to check the squish clearance to see if the cylinder gasket can be omitted and the cylinder sealed to the crankcase with a good sealant, many things will work well, Dirko, Hondabond, Yamabond ,Permatex anaerobic and Seal All to name a few. A clearance of .019 - .022 is considered safe, I run much closer but watch my fuel mix very closely to prevent carbon buildup on the piston crown. A muffler mod is easily doable for most anyone, these two changes are a start and get fair gains on the 044, real port work and more extensive machine work will really bring out greater gains.
     
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  6. SamT1

    SamT1 ArboristSite Guru

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    Thanks. I have tools to check deck height and stuff, I used to build the performance VW bug engines. Will that change my fuel octane requirement if I went into that .019-.022 range?
     
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  7. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    No, not on a chainsaw engine.
     
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  8. SamT1

    SamT1 ArboristSite Guru

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    Well we failed the compression test this evening. I couldn’t even hit 120. No wonder this saw feels a lot weaker than my twin. (It does have somewhere between 400 and 500 cords on it) I tore it down to the jug, but I need a lot of brake cleaner to get it clean enough to go further. Looking in at the piston everything looks really nice besides the rings. They look very loose to me. Like they barely touch the wall.

    So next I clean the sucker up and pull the jug off and see what’s up? Do I just stick new rings in it and go again or since it’s high hours go farther? I see all the big bore kits, what’s the skinny on going 52mm vs just re ring and muffler mod?
     
  9. Jasonrkba

    Jasonrkba Addicted to ArboristSite

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    Just depends on your budget. Rings, bearings, seals and gasket deletion might set you straight. Although 400/500 cords of wood is a lot of cutting.
     
  10. motorman1

    motorman1 ArboristSite Operative

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    Rings and likely good to go.
     
  11. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    Depends on how much the piston is worn. Check clearance between the piston and cylinder wall, if its more than .005 then definitely use a new piston. New would be around .002 - .003, ring end gap .006 - .009
     
  12. SamT1

    SamT1 ArboristSite Guru

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    Sounds good guys. Do you need to hone the cylinder or do any other kind of prep?
     
  13. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    For my builds I just give them a good polish with red/ reddish brown Scotchbrite pads, they will remove the glaze but not damage the cylinder lining. Chainsaw cylinders do not need a sharp crosshatch for the rings to seat in, they may take up to 10 tanks of fuel run through before they reach their max compression.
     
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  14. motorman1

    motorman1 ArboristSite Operative

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    Oven cleaner works good too. Do not leave it on very long though. I've had a few high hour saws and fortunately, I've only had to replace rings and rubber parts to freshen them up. Usually just fuel lines, rings and carb diaphragms. YMMV.
     
  15. SamT1

    SamT1 ArboristSite Guru

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    I took the jug off tonight. Rings don’t look bad. See pics attached. Is that rod supposed to be blue? Piston may be a little worn.

    What do y’all vote to replace? Need any measurements?
     

    Attached Files:

  16. SamT1

    SamT1 ArboristSite Guru

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    Sorry hit sent too quick.
    8EE40E4A-7492-4548-AF88-08BD8D2CB549.jpeg
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  17. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    You must check the bearings on the big end of the rod at the crank pin, any up and down slop would be bad, side to side movement is ok as the needle bearings will allow that. The blue color is from heat treatment at the manufacturing level.
     
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  18. ncfarmboy

    ncfarmboy Addicted to ArboristSite

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    If it was mine I would put a new Meteor ($38.00 or so) in it comes w/Caber rings. That's what I did when I picked up an 046. Same for my 395.
    Also did a little grinding on the 046 as the skirts are wider on the Meteor than OEM. It's an animal and I'm a Dolmar man.
    Shep
     
  19. SamT1

    SamT1 ArboristSite Guru

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    No play it feels excellent to me.

    I have a meteor piston coming now. Hopefully I can run it without the gasket. I guess I’ll start tinkering with the muffler when the kids are asleep.
     
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  20. SamT1

    SamT1 ArboristSite Guru

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    I did the muffler this evening too. Only took 30 minutes. Turned out pretty good I think for a guy that knows nothing.
    I drilled another hole about 1/4 inch from the original and then cut out the bridge between them. It’s around 80% of exhaust port siZe. Still under the factory spark arrestor (not pictured). What do y’all think for a first time job.
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