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Stuck Piston on Solo 90cc Milling Saw

Discussion in 'Chainsaw' started by max2cam, Mar 8, 2009.

  1. max2cam

    max2cam AboristSite Guru

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    Well, it happened. I was out milling a big red pine log the other day into big wide 15" boards when my Solo 690 might have stuck the piston while making the cut.

    The chain had gotten pretty dull and the bar hot, so I stopped and sharpened the chain, let the saw cool off for 10-15 mins and resumed cutting. I hadn't gotten very far when the saw abruptly quite in the cut. I instantly thought: "Oh no!" and when I pulled the starting cord it didn't budge.

    I thought that was that, but later the engine did turn over (cooled off?), and yesterday I started it and it seemed to run okay. So now I wonder what the heck to do. Today I'll take off the covers and see if I can find any air leaks. Also will make sure it is "4-stroking" when operating. I rather think it was, yet when the chain was dull it seemed to be running awfully fast. But of course now I'm questioning everything.

    I use a 40:1 mix of semi-synthetic aircooled 2-stroke engine oil (Citgo) with premium gas and I always shake the gas can.

    Any tips or advice on what to do? I'm trying to convince myself that it really didn't stick and I just forgot to press the compression release when I first tried it, but that's probably wishful thinking. More likely I had a minor seizure that un-seized itself when the saw cooled down. I know I should pull the muffler and look at the piston for scoring, but since one muffler screw is stripped and JB welded in, I'd rather not do that.

    Thanks

    PS: Why don't chainsaws have auto shutdown when they get too hot?
     
  2. blsnelling

    blsnelling Site Sponsor

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    Do not start it again until you pull the muffler and check out the piston. If nothing else, take a peak through the sparkplug hole. You likely scored it and running it will only serve to further damage the cylinder.
     
  3. PB

    PB Addicted to ArboristSite

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    The oil sticks out as a red flag to me. The Citgo oil is made for many things, but not specific for chainsaws. Milling is hard on a saw, and buying better oil is good insurance. Stihl or Husky oil is good, or any saw manufacturers branded oil.

    Like Brad said, don't start it until you figure out why it stopped. You could ruin it beyond reasonable repair.
     
  4. thomas72

    thomas72 Addicted to ArboristSite

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    I do not know about today but a while back they made a automotive spark plug that had a thermostat built into it. If the head temp got to hot it would kill the spark. It must not have worked to good in those days and not have been reliable for them to quit making them.
     
  5. Orange Hill

    Orange Hill ArboristSite Operative

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    I would also check the spark plug to see what the insulator looks like to see if there is an melting, glazing, blistering and what color it is after you take a look at the piston. Was the saw set up to run at 50:1 and then richened up to run 40:1? How long have you been milling with the saw?

    Citgo huh, looks like Caesar Chavez took down another capitalist swine flaunting his freedom and power to buy and use powerful Italian chainsaws!!! Seriously I would not trust oil from a nationalized Venezuelan oil company. They can barely feed their people, I doubt they are putting much effort into improving or maintaining the quality of their products.
     
  6. SawTroll

    SawTroll Information Collector

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    :agree2:
     
  7. Brmorgan

    Brmorgan Addicted to ArboristSite

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    I think you mean Hugo Chavez... Cesar Chavez was an American civil rights leader. And there are more people living below the poverty line in the US than the entire population of Venezuela.

    As for the saw, I wouldn't run it until inspecting the cylinder. You might have had a ring catch and break, in which case there could be a little piece of ring rattling around the crankcase.
     
  8. max2cam

    max2cam AboristSite Guru

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    Okay, I will not run it again until I check it over. Might have to pull that muffler off...

    I've been using 40:1 all along (spec is 50:1, I think, but I believed a little more is better as many guys here advocate). I've been milling with it for 4-5 years on and off. This year I milled 3 logs (15" lumber) and was working on the 4th log when this event took place.

    The Citgo 2-stroke oil says "Made in USA" (Tulsa, OK) and meets international standards for "air cooled 2-stroke engines: ISO EGD and JASO FC." Ain't that good enough for a (ahem) German-made (not Italian) chainsaw?
     
  9. fourfivefour

    fourfivefour ArboristSite Operative

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    You can drill and tap JB weld. Pull the muffler and have a look. If it's ok, use the quick dry JB weld (so you don't have to wait) and get back to milling.:chainsaw:
     
  10. Jacob J.

    Jacob J. Tree Freak

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    There's also roughly 11.5x as many people in the U.S. as there is in Venezuela, so that's not really an accurate comparison.
     
  11. mountainlake

    mountainlake Addicted to ArboristSite

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    Are you runninng good gas or did you get converted to ethonal lately? If you don't find a air leak make sure it's running plenty rich for milling. Steve
     
  12. max2cam

    max2cam AboristSite Guru

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    Disaster Update:

    Well, I did pull the muffler and it looks like I won't be going back to milling in the near future at least.

    First, I pulled the spark plug and it looked okay. A little dark and sooty but not glazed or melted or white or nasty at all.

    Then I looked down the sparkplug hole and as much of the cylinder bore I could see looked fine.

    But I knew I had to pull the muffler so I did. Those screws were in there nice and tight too!

    Alas, with the muffler off the crime scene was revealed. On the piston right at the exhaust port (where else?) the skirt was somewhat galled and also at the piston rings which looked stuck in their grooves from a little displaced aluminum from the piston.

    Not the news I was looking for but the truth of the situation.

    Of course now I wish I hadn't started it yesterday, but you know how it goes. I don't have the heart today to pull the cylinder off but will do that tomorrow most likely. Almost certainly it will need a piston and rings and (yikes) maybe a cylinder. Tell me it ain't so!

    So how score resistent is that Nikisil coating? I believe that's what this German Solo saw has in the cylinder. Isn't that supposed to be tougher than diamonds or something? I think I can still get parts, but not cheap aftermarket ones that I like best.

    I should have been more careful and observant, etc. etc. etc. No doubt it was somehow my fault. I did get to the point where I just thought I could mill and mill and not pay much attention to things but all those nice clean white wide pine boards.

    Now I remember why I HATE 2-stroke engines!
     
  13. Jacob J.

    Jacob J. Tree Freak

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    It's likely you'll be able to clean up the cylinder and throw a new piston in there...
     
  14. max2cam

    max2cam AboristSite Guru

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    I use premium gas but in Wisconsin it may have ethanol, like 10 percent. Tell the truth, I don't pay much attention to that, but I probably will start.

    Yes, I'll sure make certain I'm running rich in the future, but I'll have to make some repairs first....
     
  15. max2cam

    max2cam AboristSite Guru

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    Thanks for the vote of confidence in the direction of HOPE. I certainly hope it's true. I like this big 90cc saw and enjoy milling my own trees when an occasional big old red pine dies. This one was 90 years old and had a 28" butt log. Big enough to kill my saw at least, with my help of course. Unless of course there was an air leak....
     
  16. Jacob J.

    Jacob J. Tree Freak

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    The 9010 is a good saw and should last you a long time provided you keep the maintenance up on it and switch to a better oil.
     
  17. PB

    PB Addicted to ArboristSite

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    Isn't the 694 equivalent to the 9010? He has the 690.
     
  18. Jacob J.

    Jacob J. Tree Freak

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    I thought he had the Dolmar 9010, I must have been thinking of someone else. There's so many people and saws here, I can't keep track.
     
  19. max2cam

    max2cam AboristSite Guru

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    I've got a Solo 690 which is different than the 694 as you know.

    In any case, I will use the BEST oil in future, but this Citgo 2-stroke oil is "Made in USA" (Tulsa, OK) meets international standards for "air cooled 2-stroke engines: ISO EGD and JASO FC."

    I didn't think it got any better than that. Really. I thought that were the highest standards. What's better? Seriously, even with the risk of this becoming an oil thread.
     
  20. Jacob J.

    Jacob J. Tree Freak

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    I don't know anything about Citgo oils and I've never used them. If you're milling though, I think a full-synthetic is in order. I've been using Silkolene for milling.
     

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