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Is deleting the base gasket generally a safe mod?

Discussion in 'Chainsaw' started by teacherman, Aug 11, 2017.

  1. teacherman

    teacherman Sawturated

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    for a modern Stihl pro saw? I am leery of the grinding, especially enlarging port openings and disrupting the nikasil cylinder liner. But in general is it safe to just drop the gasket, or does that run a risk of not enough squish room? I've been messing with saws a while, but I'm not much of a modder per se.
     
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  2. cus_deluxe

    cus_deluxe Thats what she said.

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    Generally, yes. Just lightly bolt down the cylinder and check the squish woth a piece of solder stuck through the plug hole. Just be careful that the piston is above the exhaust port when checking. Also use solder somewhere around .025 thickness. Roll piston past TDC, and measure with micrometer. The bigger the solder, the less accurate this method will be.
     
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  3. cus_deluxe

    cus_deluxe Thats what she said.

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    .020 is pretty generally accepted as the minimum safe squish for most applications.
     
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  4. teacherman

    teacherman Sawturated

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    OK, thanks for that. I like the idea of being able to slip it in the plug hole. I heard before you have to unbolt and slip the jug off, and have several little bits of solder on various part of the crown, stuck on htere with grease, then torque it back down and then unbolt it again to check and so forth. Seemed like more of a pain than it's worth that way. I'd have to put in some HeliCoils after a session of that nonsense...
     
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  5. teacherman

    teacherman Sawturated

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    I have some super-thin electronic solder that should work out great!
     
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  6. Ozhoo

    Ozhoo ArboristSite Guru

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    .020 off the flywheel key is another generally accepted safe mod. Along with a muff mod, those things things make a nice performance boost.
     
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  7. Ted Jenkins

    Ted Jenkins Firewood by TJ

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    I would say the compression ALL depends on where you live. The lower the altitude the higher the compression is. The shape of the combustion area is indeed important. A small amount of compression increase can be a great thing, but if every thing else is perfect it still can cause a loss of power. Higher compression with more advance spark in areas above 4,000 feet would cause performance gain. However at sea level with more compression can produce more torque and less over all power. Rule of thumb more torque means less RPMs. Thanks
     
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  8. Free Will

    Free Will August is take a cop to lunch month.

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    Depends on who's looking for me.....and why.
    Seems like a lot of hassle for something that you may not even notice.
     
  9. teacherman

    teacherman Sawturated

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    What does this mean? Taking out the key and sanding a sliver off of it, and holding the flywheel counterclockwise with a piston stop in place so it's a degree or so advanced? I turned the flywheel of an 088 back the other way recently because I couldn't start the dang thing, it was snatching the handle out of my hand so much. It did seem a bit loose rotationally, so maybe that's what a previous owner did with it. Maybe it has no gasket...
     
  10. Ted Jenkins

    Ted Jenkins Firewood by TJ

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    Making the muffler a little larger and opening it up a bit is a pretty safe mod. Advancing the spark a couple degrees via the crank key is another accepted mod, but will produce a bit more heat.
    "Seems like a lot of hassle for something that you may not even notice."
    I have more saws than most and use them more than most so modding saws is not a big priority. Normal for me is working at 6,000 feet, but as of late 3,500 is normal. So it would be a major hassle to have to go through much retuning for the altitude. Thanks
     
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  11. Moto Vita

    Moto Vita ArboristSite Member

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    Do those of you that remove base gaskets raise the transfer and exhaust ports at the same time, or do you feel that the increased compression outweighs the loss caused by lowering those ports?
     
  12. cus_deluxe

    cus_deluxe Thats what she said.

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    I never have, id end up doing more harm than good im guessin haha. Never done the math but probly only a couple degrees of difference, depending on how thick the gasket is
     
  13. Little Al

    Little Al Addicted to ArboristSite

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    To check the Squish correctly you require at least 3 pieces of & I prefer the plastic type checking strip. You may possibly get a fairly accurate reading with a piece at fore/aft 90degrees to the piston pin any less & the piston can & does tilt & gives a false reading & 3 is better the extra one being in the piston centre
     
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  14. Sleepy

    Sleepy Grumpy Old Man

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    http://www.plastigaugeusa.com/how.html
     
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  15. teacherman

    teacherman Sawturated

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  16. stihlaficionado

    stihlaficionado God of ArboristSite

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    Every gasket delete/squish reduced saw I've run is very noticeable. Saw doesn't need a port job to run strong.
    A mm coupled with a what the OP wants to do will produce good results
     
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  17. pro94lt

    pro94lt Addicted to ArboristSite

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    It's safe... I've got a dozen saws or so running with the gaskets removed running 5 days a week... It's deffinantly worth it.
     
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  18. BusyBeaver

    BusyBeaver ArboristSite Lurker

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    What should one use as a sealer when no gasket?
    CG
     
  19. teacherman

    teacherman Sawturated

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  20. teacherman

    teacherman Sawturated

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    This is excellent! It will give me a reason to give a few saws a good cleaning, ones with fully adjustable carburetors.
     

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