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Think you know two-stroke engines?

Discussion in 'Chainsaw' started by 1Alpha1, May 17, 2018.

  1. 1Alpha1

    1Alpha1 100% USDA certified abnormality-free.

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    Depends on who's looking for me.....and why.
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  2. Bobby Kirbos

    Bobby Kirbos Scrounger of Cellulose Based BTUs

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    24/30 = 80%

    I passed.
     
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  3. 1Alpha1

    1Alpha1 100% USDA certified abnormality-free.

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    Your diploma is in the mail. ;)
     
  4. Canyon Angler

    Canyon Angler ArboristSite Guru

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    "Small four-stroke engines commonly have compression ratios of 12-to-1"???

    Really? My 1969 Pontiac 400 had a compression ratio of 10.75-to-1 and required high-test gas...I always thought that was fairly "high" compression, and that small 4-stroke engines would be less than that, not more...
     
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  5. CJ Brown

    CJ Brown "I learned this from a hockey card..."

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    Gasoline type ignition? 32:1 typical oil ratio? Both ports open at start of stroke?

    I guess I need to go back to school and brush up :crazy:
     
  6. Bobby Kirbos

    Bobby Kirbos Scrounger of Cellulose Based BTUs

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    I'm still trying to figure out how the oil gets introduced in the carburetor .
     
  7. ironman_gq

    ironman_gq Addicted to ArboristSite

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    Mixing UK terminology in there really mucks up the questions. Pretty sure this quiz was written by someone with no knowledge of engines reading notes that were submitted by a months worth of "caller number 9" people on the local radio.
     
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  8. ericm979

    ericm979 ArboristSite Operative

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    100% (because I know UK gearhead slang) but a lot of the questions are dumb. The both ports open at the start of the cycle- they must mean the start of the intake event, where on piston port engines the exhaust is often still open. But that's not a requirement.

    Ok guys, another question: what's the engine in the picture?
     
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  9. CJ Brown

    CJ Brown "I learned this from a hockey card..."

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  10. Cope1024

    Cope1024 Stihl Crazy

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  11. JimM

    JimM ArboristSite Guru

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    How did ‘you’ do?
     
  12. Mustang71

    Mustang71 Addicted to ArboristSite

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    The compression ones are odd. I don't think the push mower is running at 12:1 and I don't think the stihl is running at 6:1. The push mower gets 87 octane and the saws get 91 I must be doing it wrong.
     
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  13. tomdcoker

    tomdcoker Addicted to ArboristSite

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    18/ 30. Summer school here I come.
     
  14. 1Alpha1

    1Alpha1 100% USDA certified abnormality-free.

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    Depends on who's looking for me.....and why.

    Don't know why you'd care, but whatever........

    [​IMG]
     
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  15. CR888

    CR888 Addicted to ArboristSite

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    26/30. Yeah the oil originating in the carburetor was a tricky one. The multiple choice was something like: sump, carb or neither. I selected neither & got it wrong.
     
  16. spyder62

    spyder62 ArboristSite Operative

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    Cmon guys, need some more answers before I take the test
     
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  17. smokey7

    smokey7 jack of a lot ace of a few

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    Goofy questions but fun non the less. Didnt know bigger 2 cycles were more efficient. I got it right but didnt know for sure. I found it funny required oil ratio was 4 oz to gallon. Thsts what i do so Thats good lol
     
  18. Little Al

    Little Al Addicted to ArboristSite

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    Same way as the gas as it's mixed with it
     
  19. Canyon Angler

    Canyon Angler ArboristSite Guru

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    Overall, the questions seemed to be either ridiculously easy ("A two-stroke engine operates on how many strokes?") or puzzlingly vague... like all the words were there, but were mixed up in a bingo cage before the question was phrased.

    Plus, for some reason (I'm guessing because I use a Mac), I got no score at the end.
     
  20. ironman_gq

    ironman_gq Addicted to ArboristSite

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    Most are in the 6-8:1 on 2 strokes, older flathead 4-strokes were about the same and most modern 4 strokes are in the 8-10:1 range. Only way they're seeing that kind of ratio is if they're taking full cylinder volume to compressed volume which is very inaccurate on a 2-stroke. The true ratio is the swept ratio, it starts measuring at the top of the exhaust port.
     

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