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Pros and cons of base gakets

Discussion in 'Technical Area' started by chisel, Dec 31, 2016.

  1. chisel

    chisel Well-Known OPE Member

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    Hey guys,

    I know removing the base gasket has its benefits. Higher comp, Better squish, moves the ports in a good direction etc etc etc.

    BUT, it has been brought to my attention that the base gaskets acts like a cushion for the massive amount of vibration happening.

    So the real way raise comp etc is by machining the cylinder base and keeping the gasket.

    Is this correct?
     
  2. Moparmyway

    Moparmyway Its just a saw

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    In most every case, running a base gasket means having to cut more off the base itself.

    I love a no gasket, 518 approach. Easy to assemble, easy to clean if taken apart, keeps the cylinder base as thick as you can.

    Some saws have thin cylinder bases to begin with, others have enough meat to not have to worry about getting too thin

    I'm sorry, but I don't believe in the cushion theory. After you remove a few cylinders, it becomes obvious that them bolts are very, very tight. Some gaskets are metal from the factory, no cushion there
     
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  3. Al Smith

    Al Smith Pinnacle OPE Member

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    It's more of a preference than anything .In my case because of several occasions of miscalculating piston to head deck clearance gaskets have worked out very well plus I have gotten really good at making them .
     
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  4. mdavlee

    mdavlee Hillbilly grinder

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    Only reason I like gaskets in most is ease of use. Certain saws I don't like to use them since the bases are prone to cracking seems like anyway. 390 is the one I try to use sealer on all I can.
     
  5. Deets066

    Deets066 AKA Deetsey

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    As stated, it really depends on the saw. I like the idea of having a gasket, even if it's a thin one that requires sealer with it.
    For the guys that use sealer, when you pull a jug that has had sealer on it. How much sealer appears to be on the Mateing surface?
    Almost none, in my eyes I feel a gasket has a better survice life than no gasket. And I'm talkin about steel coated gaskets
     
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  6. Al Smith

    Al Smith Pinnacle OPE Member

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    I think if you look at things like a 390 Stihl which is a clam shell design as are 10 series Macs ,many Poulans they used a sealer to begin with .Rather I assume a 390 does .
    Cylinder bases unless you cut out the top of the cylinder to decrease the combustion chamber area you aren't removing enough metal to weaken the flanges on the cylinder to any degree .

    Then again it has a lot to do with the brand and model .The P100 Partner I'm tinkering with does not have external flanges like Stihl and the metal has to be close to 3/8" thick .
     
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  7. Stackowood

    Stackowood Super OPE Member

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    I have always used base gaskets. On some saws like the old 2077 it also acts as an insulator to reduce heat transfer to the crankcase. Also don't like pulling apart saws where someone used sealer and having to clean up the mess.
     
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  8. Al Smith

    Al Smith Pinnacle OPE Member

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    Now then on a simple gasket removal on a Stihl which uses a 20 thou thick gasket it would raise the comp .The exhaust will be a little longer,the transfers would not change the intake would be lowered some . With sealer you probably effectively lowered things by say 18 thou figuring 2 thou for the sealer .

    Combine all that with some rework of the muffler and it more than satisfies most people because as simple as all that is it does work .To get more you have to carve away with a die grinder .Most are reluctant to do much of that ,uncharted territory .It's all good though just depends on how deep you want to go with it .
     
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  9. mdavlee

    mdavlee Hillbilly grinder

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    518 isn't bad to clean up or the ones like it. Most will wash away into the chamber and out to the muffler on first start up since it won't set up in the absence of air.
     
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  10. Deets066

    Deets066 AKA Deetsey

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    I've only used yamabond 4, clean up is easy
     
  11. mdavlee

    mdavlee Hillbilly grinder

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    Motoseal can be a pain to clean up compared to 518
     
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  12. Moparmyway

    Moparmyway Its just a saw

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    Acetone makes 518 just wipe away
     
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  13. chisel

    chisel Well-Known OPE Member

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    Thanks for all the input guys.

    Seems theres guys on both sides of the fence. With my saws my number one goal is longevity with performance being important, but not as important as reliability.

    so theres the cushion thing, and also as another posted stated the metal to metal heat transfer thing, is it a big deal?....probably not so much, but something to think about.

    anyone here had a baseless saw fail because of the lack of a base gasket? how long has your baseless saw been running?
     
  14. Deets066

    Deets066 AKA Deetsey

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    I've had them leak because of a bad gasket, but it had been reused a few times
     
  15. Deets066

    Deets066 AKA Deetsey

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    I've also questioned the sealer and pulled it off and redid it, never was certain if it was leaking or not
     
  16. mdavlee

    mdavlee Hillbilly grinder

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    I've put a few together with no sealer. They ran without an air leak. I had just completely forgot the sealer.
     
  17. awol

    awol Pinnacle OPE Member

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    Well this is just my opinion, but here goes!

    I prefer to assemble them gasketless; the cushion question is a non-issue, and the greater the heat transfer from jug to case the better. If every part of the saw can run closer to the same temperature there will be less thermal expansion and contraction, and thus, less wear. I've never had to tear down a gasketless saw to fix a base leak, but have had to tear down lots of saws because of blown base gaskets. Also, when doing very much R and D on a saw, I can assemble and run it gasketless and sans sealer without untunable leakage if I did a good job machining the case and/or base. And then too, the thicker the ears of the base, the stronger it will be; this is more important on some models than others.
     
    Last edited: Dec 31, 2016
  18. MG2186

    MG2186 Pinnacle OPE Member

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    So 515/518 is permitted as an adequate base sealer? I thought everyone always preached you had to use 3-bond,Honda bond/Yama/bond/motoseal type sealant. I would much rather use 515/518, much easier to clean up


    Sent from my iPhone using Tapatalk
     
  19. Moparmyway

    Moparmyway Its just a saw

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    OK , I might as well be the one to do it.

    Yes !

    You have permission to use 518, I'll permit you to use it

    :smile:
     
  20. MG2186

    MG2186 Pinnacle OPE Member

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    Lol.. thanks


    Sent from my iPhone using Tapatalk
     
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