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When to replace top end

Discussion in 'Chainsaw' started by mbrick, Sep 8, 2018.

  1. mbrick

    mbrick ArboristSite Operative

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    I have a good running 550xp, I believe it is a 2012 model with 3 piece clutch. I bought it used for $375 in 2015 and have used it seasonally since. It was more used than I was led to believe, but not beat up. Photos attached of condition when I bought it.

    How can I tell if it needs a top end? Do you normally replace them at a given interval or run them until the compression is low and hard to start?
    I haven't worn one out yet to know if they last until there is a catastrophic failure, or if the compression does fade over time. It could be a little down on power since I got it but it's hard to say for sure.

    I see Husqvarna OEM top end kits (cyl, piston, ring, clips, wrist pin bearing) are only $113 for the 550xp.
    Are the cylinders nikasil plated or matched to the piston? If so, I could get a OEM piston kit only for $55.

    I've never used the decomp button, is that a sign it needs a top end?

    Thanks.
     

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  2. Conquistador3

    Conquistador3 Le Comte de Frou Frou

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    There's an old saying: "If it ain't broken, don't fix it".

    That's all I have to say.
     
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  3. Chainsaw Jim

    Chainsaw Jim CJ Saws, LLC

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    The piston still has all the machine marks visible indicating no wear on the exhaust side.
    You can take it to a husqvarna dealer to have them hook it up to the computer if you're concerned about how much run time it has.
     
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  4. Mad Professor

    Mad Professor Addicted to ArboristSite

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    Pic of ex shows very little wear but running rich. Adj. carb. Might want to take a look at piston again. It rich mix can cause carbon scoring. If piston still looks good I'd just run it unless a compression test is low, then ring it sometime soon.
     
  5. mbrick

    mbrick ArboristSite Operative

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    That photo was from when I got it, so I knew I was starting in good shape. I will have to grab a pic of it now, a few years later.

    The only nearby dealer wants $85 to plug it in and check the autotune data. Ugh. Yes, I would like to know the run time info.

    I wasn't aware I could adjust the carb since it is an autotune saw. I hear it adjust during the first few long cuts of the day.

    My compression tester set does not have an adapter for the smaller 10mm plug hole on these, and if I make something the extra volume will affect the readings?
     
  6. Mad Professor

    Mad Professor Addicted to ArboristSite

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    That's why I hate new saws, $85 to plug it in. WTF? Have not dealt with those, nor will I, not sure how user friendly to tune. Almost all my saws are even pre-limiter crap. (pun intended)

    I'd save the $85 and put it towards a spare OEM P/C assy.

    Husky dealers, is it really $85 just to plug in a diagnostic?

    I hate new cars/trucks too.............looking at a 1973 chevy PU right now.
     
  7. ChoppyChoppy

    ChoppyChoppy Addicted to ArboristSite

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    Why shouldn't the dealer charge?

    They had to buy the equipment, plus train someone on it, not to mention all sorts of other expenses.. anything from building heat to the displays the saws are on.

    We get people from time to time expecting that their *** be fixed for $20 or something. They get pissed when I tell they it's not worth their time or mine to figure out the 10 year old $100 "throw away" push mower or Walmart chainsaw.
     
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  8. holeycow

    holeycow Addicted to ArboristSite

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    Don't worry choppychoppy, the dealer has to charge, but there is a solid movement of professional saw hands away from autotune/mtronic for that reason alone. They cannot adjust their saws and are very tired of having equipment down while being somewhere out in the bush (where many of these guys work for many days at a time with little or no access to a shop).

    If there was a legitimate alternative, Stihl and Husky electric controlled saws would be gone in my world. The pro hands are searching for that alternative.

    Not that many years ago saws were routinely rebuilt/freshened on a tailgate before work in the morning, or at the end of the day (topends, carbs, etc). Not any more and that has some experienced hands pissed.
     
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  9. ericm979

    ericm979 ArboristSite Operative

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    Electronic metered carbs don't keep you from rebuilding the top end. I'd like to know how one reads the run time from an old fashioned carb saw.
     
  10. holeycow

    holeycow Addicted to ArboristSite

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    who cares about reading the run time. It is useless information.

    look at an old saw. Many of them can be torn down to the cases in literally minutes.

    well, it is not useless information, but you sure don't need the saw to keep track of that, as it can be done easily without.

    Like I said, nobody who has run saw for many years is very impressed with the new stuff. They run it because they are forced to, basically.

    techies like it, gearheads don't

    yesterday's conversation with 20yr veteran.. Him: "I've got 2 echo 620's on order; should have them on Tuesday". Me: "wow, that's taking a chance. I have a 590; it's growing on me. The 620 should be a stronger, better saw. Give it a chance, it will feel a little funny at first, but give it a chance, you might like it!" Him: Ya, I'm getting tired of not being able to tune my saws, and why should I have to take it to a dealer and pay money for diagnostics when I can easily diagnose my own saw if I wasn't constrained by this goofy ****" Me: "yup, I am not interested in one of those saws, period. Hey, guess what?, I just bought a 262xp, here's a pic on my phone" Him: " Looks nice for its age! I ran a couple of 266's for quite a while; I wish I could still buy those saws today" as he's packing his ms261 and ms362 into the argo...



    Yesterday.
     
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  11. Mad Professor

    Mad Professor Addicted to ArboristSite

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    Runtime tells you squat about how the saw has been run. How long it's been run yes, but not if it was taken care of or abused.

    An older saw? Pull the muffler, look at the piston and do a compression test. If that checks out but there is problems still, a pressure/vac test is in order. Only simple tools are needed that won't cost much more than plugging a new one in for diagnostics. Once those simple tools are in hand (compression tester/mighty vac), you own them, and they can be used over and over. My saws don't have limited coils and I tune in them in the wood. I don't have a tach for my saws.

    I don't need electronic crap to tune a saw for me, nor want to be forced to take it to a dealer when the electronics are fubar. I'm sorry for dealers if they have to pay big $$$ for equipment to work on the new saws.

    I want a simple electronic ignition and a carb with adjustments. The ignitions are generally good, or bad, and can be replaced in a few minutes. Carbs are simple and inexpensive to rebuild.

    As far as $85 to plug a saw into a diagnostic, I feel that borders on robbery. I have a dealer, that if I bring in a clean saw with clutch and flywheel off, he'll put seals in for $20 labor. I have seal pullers but they are not near as nice as the ones in a stihl tool kit. The same with case splitters. Those are about the only two things I'll have a dealer service, and if I do I know which dealer to go to.

    I'm happy I have a slew of older saws that are in great running condition, most that I've rebuilt or refurbished myself. I also have NOS OEM wear parts (P/C kits, pistons, gasket sets, carb kits, rubber parts) for most, and some used carcasses if I want a used part. I have no desire for any of the newer saws. I'll bring an extra air filter with me into the woods and deal with older AV mounts vibration. That's about all I wish my older saws had, better filtration and AV.
     
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  12. Charles Bale

    Charles Bale ArboristSite Member

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    If its running good:

    Non ethenal gas, good oil, keep your filters clean .... saw will run for another 10 years.

    I can tell if it has compression everytime I start it.

    Run it, be happy
     
  13. mbrick

    mbrick ArboristSite Operative

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    Ok, will do. I'll keep my eyes open for any deals on a cylinder/piston kit to keep in stock.

    Yes I go out of my way to get non-ethanol gas for the yard equipment. It's hard to find but worth it.
    I blow the air filter out regularly, sharpen the chain every tank of gas, and run Husky XP premix at 40:1.
     
  14. Big_Wood

    Big_Wood westcoast dweller

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    If guys actually saw what these saws go through under professional use they would realize they stand no chance of actually wearing one out for a legitimate reason even at 50:1. It’s usually bad gas that gets a weekend cutter.
     
  15. Charles Bale

    Charles Bale ArboristSite Member

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    Bad gas, and leaving the gas in the carb when you put it away for more then 3 months (I drain everything I have if its not gunna be used for a month, takes 2 mins)
     
  16. mbrick

    mbrick ArboristSite Operative

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    Yes, before storing I drain the fuel tank then make sure its completely dry. Then push the prime bulb repeatedly until it is just moving air to get all of the gas out of the carb and into the tank, then dry the tank again.
     
  17. Mad Professor

    Mad Professor Addicted to ArboristSite

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    Real carbs don't have/need prime bulbs. LOL
     
  18. holeycow

    holeycow Addicted to ArboristSite

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    There are two schools of thought on storage.

    One says drain, one says fill. I happen to fill. Works for me.
     
  19. mbrick

    mbrick ArboristSite Operative

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    Prime is probably not the right word, it is an air bleeder. It just pulls fuel through the carb and recirculates back into the tank. It's not spraying raw fuel into the throttle body.
     
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  20. Big_Wood

    Big_Wood westcoast dweller

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    I leave fuel in my saws. When I go to use next I dump and put fresh in if they’ve sat to long. I’ve had spare saws sit 2 years, swap the fuel and they run fine. Recently though I’ve been running a lot of company fuel which is typically what they can get cheap. Aka **** lol I notice that if I leave it it goes nasty and even seems to swell fuel lines. Real hardcore ethanol stench. I haven’t worked since before fire season which is about 2 months and the saws I was using all have the inside of the tank portion of the line swelled. I actually ran some stabilized premium through them today the get that nasty **** out of their system since I need them in a week.
     
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