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Stroking a Dolmar 7900

Discussion in 'Chainsaws' started by Fruecrue, Nov 5, 2018.

  1. mettee

    mettee Super OPE Member

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    So you cut squish, what did you end up doing with the base? How much squish did you cut out?
     
  2. Fruecrue

    Fruecrue I got wood

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    .060” out of the band with OEM base gasket, no base cut.
     
  3. mettee

    mettee Super OPE Member

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    How did that leave your numbers?

    I can't remember did you bump timing when you did the coil
     
  4. Dub11

    Dub11 Some body poisoned the watering hole!

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    leave the AF at home, it'll stay clean that way.
     
  5. Fruecrue

    Fruecrue I got wood

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    95/123/78
    Husky coil 30 degree flywheel advance from stock position.
     
  6. huskihl

    huskihl Sausage Fingers Forever

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    Did you go for a little more intake or leave it at 78? Guessing you left the others where they were?
     
  7. Fruecrue

    Fruecrue I got wood

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    Intake landed there. 83 was my original thought but that 78 sure was a convenient place to start.
    After base cut, with stock gasket, 109/144/78
     
  8. mdavlee

    mdavlee Hillbilly grinder

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    What’s compression like? I never took more than .035” and they would be 200 or a touch over
     
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  9. Fruecrue

    Fruecrue I got wood

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    D2FF4B2D-595B-4BEE-95C1-6672203D11F4.jpeg Tuned it in the garage night before, this was first thing this morning. Felt like it went up throughout the day.
     
  10. huskihl

    huskihl Sausage Fingers Forever

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    Oh. I was thinking you had good squish after only the band cut. I doubt you can raise the exhaust above 100 without grinding through the flange. Maybe with a bell mouth you can
     
  11. Fruecrue

    Fruecrue I got wood

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    I’m sorry, meant to write band cut.
    I did not cut the base.
     
  12. Fruecrue

    Fruecrue I got wood

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    Parttard thing again.
     
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  13. huskihl

    huskihl Sausage Fingers Forever

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    I see. That makes sense.
    I originally ported a bb for mine and went through the flange roof trying to go straight out at 95. Guessing the oem has a thicker roof
     
  14. mettee

    mettee Super OPE Member

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    Okay so a normal after porting set of number in a 7900/7910 would be 98-100/128/85....roughly.

    I gotta draw this out and see how the two compare. It still confuses me a little bit.
     
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  15. chipper1

    chipper1 Pinnacle OPE Member

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    Need a stock one to try :cool:.
     
  16. huskihl

    huskihl Sausage Fingers Forever

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    Just gotta send it
     
  17. Fruecrue

    Fruecrue I got wood

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    Some guys wouldn’t do that much intake.
    78-83 for a work saw.
     
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  18. redlight066

    redlight066 Super OPE Member

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    Fine looking work Dave. Great thread.
     
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  19. Fruecrue

    Fruecrue I got wood

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    Thank you Rich.
     
  20. mettee

    mettee Super OPE Member

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    So you hit 78, and that is actually a better number I take it? Pardon my rookie questions.
     
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