372xp piston measurements

Discussion in 'Chainsaws' started by Adamski, Jun 18, 2017.

  1. Adamski

    Adamski Well-Known OPE Member

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    Anyone have to hand the measurement from the top of the wrist pin to the piston top on a non xtorq 372xp? This saves me tearing my saw down while figuring out some measurements for my pop up piston.. thanks in advance guys.
     
  2. mdavlee

    mdavlee Hillbilly grinder

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    I have a meteor I can measure
     
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  3. rattler

    rattler Pinnacle OPE Member

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    Me too
     
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  4. Adamski

    Adamski Well-Known OPE Member

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    Yes please!! That would be super duper!
     
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  5. rattler

    rattler Pinnacle OPE Member

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    Looks like 0.648

    Sent from my SM-G935V using Tapatalk
     
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  6. old guy

    old guy Super OPE Member

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    I just did the 268 piston in the 372, the 372 pin to top is .650.
     
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  7. Adamski

    Adamski Well-Known OPE Member

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    So did you keep that base gasket to keep timing or did you leave it out and create a bigger pop up minus the gasket?
     
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  8. old guy

    old guy Super OPE Member

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    I kept the base gasket, it was .020 thick, the meteor piston was .060 taller from the pin.
    I had the shop (Deisellfitter) cut .040 deep .3975 in from the edge leaving a 30 m/m pop up, then put a 45 degree bevel on it, I'm not sure the bevel is required.
    It ended up with a .023 squish & initial comp of 172 lbs. It started the next morning with 2 pulls, the comp with the old piston & new rings was 150 lbs., I have not been able to put it in wood yet, maybe this week
     
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  9. Adamski

    Adamski Well-Known OPE Member

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    Yep this is the route I was planning on going. Thanks for all the info. Should be able to get the piston all turned down and sorted without needing to tear the saw down in the process. Do you still run the decomp? It's the one thing that bugs me about the 372 is the time it takes to pop and then start. Way more than 2 pulls. It has such an excessive squish even with the base gasket deleted. I want to get it running stock timing with an OEM gasket and have that desired squish with a pop up giving that extra compression. Then I think I will be happy.
     
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  10. old guy

    old guy Super OPE Member

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    Yeah, I kept the decomp, I am old & have 3 broken collarbones.
    This 372 has always been an easy starter but not 2 pulls easy.
    You want to know what the current squish is so it can be figured in to get what you want.
    My saw had .022 squish without the gasket with the old piston, .023 with the new.
     
    Last edited: Jun 19, 2017
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  11. Adamski

    Adamski Well-Known OPE Member

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    Woah, really the squish is that small without the gasket. It feels more when pulling it over, but then again I have been told the 372's are not the highest compression saws around.

    Thanks for the info. So I need will get the piston turned down 1mm and 10mm in from the edge and all should be fine and dandy.

    My piston is a Meteor and the base gasket is new OEM, so all these numbers should be a straight swap over to my saw..

    Thanks again!
     
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  12. old guy

    old guy Super OPE Member

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    Get your own measurements, they ain't always the same.
    I have two 357's, one has a squish of .0215, the other is .0195, without gaskets, if these small differences all stack the wrong way it can be bad.
    Get some solder & measure the squish thru the sparkplug hole.
    Also measure the base gasket.
     
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  13. Adamski

    Adamski Well-Known OPE Member

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    I know what I should do. But what I should do and will do are sometimes a bit blurred.. :risas3: But I really don't want to tear the saw down. It is currently my only working saw. I think I may wait till I have something as back up and working while this is apart. Then I will measure it properly as suggested. I have always used modelling clay and not solder. Any reasons on using solder other than it is more durable when measuring?
     
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  14. old guy

    old guy Super OPE Member

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    Yeah, you can stick solder in the sparkplug hole bent over to reach the cyl wall over the wrist pin, then bring the piston up to crush the solder, pull it out & mike the flat end.
     
    Last edited: Jun 19, 2017
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