Tuning and 4-cycling

Discussion in 'Motorized Bicycle General Discussion' started by soccerrj88, Oct 23, 2009.

  1. soccerrj88

    soccerrj88 New Member

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    Hello to all again. Got a couple questions for the 2-stroke educated. I know how they work but this 4cycling is a mystery to me. I have an 8 hp outboard 2 stroke that stutters at mid range rpm. Now that I have a cheap 2 smoke to tinker with, I now think it's 4 cycling. But so is my bike engine. At idle it runs good, with throttle open it runs perfect with power, at mid range just keeping it running it bucks and 4 cycles and jerks... open throttle it smooths out. How do I fix this?
    dnut
     
  2. pedro5189

    pedro5189 New Member

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    Change the needle height in the carb, just experiment one notch either way

    What do others think?
     
  3. soccerrj88

    soccerrj88 New Member

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    Well I did that last night, and I went up... Seemed to run worse. not really the 4cycle part, but just not top end, possibly starving for fuel. But thats what I didn't know. That carb pic post on here said stock was 2 from the top, well mine was 3 down from stock and I didn't know which direction made it richer/leaner. I have to go get some spark plugs today b/c the original is all black from break in.
     
  4. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    If you put the C clip on the top notch, that will lower the needle & restrict the fuel flow a little, making it run leaner.
    If you lower the clip, it will raise the needle allowing more fuel to flow!

    Just look at the thing, & think about how it works...

    Also... the needle doesn't do anything @ WOT; it only works in the mid-range area.
     
    #4 Venice Motor Bikes, Oct 23, 2009
    Last edited: Oct 23, 2009
  5. soccerrj88

    soccerrj88 New Member

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    ok that makes sense, but I thought it was the high speed needle, so why wont it effect WOT? what effects that, just the hole size in the jet itself?
     
  6. xlite

    xlite New Member

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    Correct-a-mundo!
     
  7. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Give 'em the 'Malachi crunch'!! laff
     
  8. soccerrj88

    soccerrj88 New Member

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    So I opened the air intake a little by opening up the holes a little and cutting off the back of them. I also opened the baffle up, by uncrimping the two pipes comeing up. I should make it richer to componsate for this correct?
     
  9. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    did you finish breaking in the engine yet?
     
  10. soccerrj88

    soccerrj88 New Member

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    Well I have about 170 miles on it and according to everyone on here, break in period is between 50 to 500 miles and anywhere from a 16:1 oil mix to 100:1 so I'm not quite sure. Right now, I'm using between a 18:1 to 24:1 mix. I put in 24 but add a little bit here and there to make sure it's oiled well because of the break in descrepancy.
     
  11. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Break in the engine with 2 gallons of 24:1, & then use 32:1 after that.
    After you have about 4 gallons total through it, you can re-jet the carb, (if it even needs it at all?)
    These engines start to run better & better the more they break in... OK??
     
  12. soccerrj88

    soccerrj88 New Member

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    alright sounds good. Thanks for the advice. One more question. I seem to be leaking oil out of the bottom of the cylinder but the head bolts are tight. Will this go away with less oil?
     
  13. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Bottom of the cylinder, or bottom of the head???
    If it's at the bottom of the cylinder it won't go away! if it's at the bottom of the head, it might just be a bad exaust gasket leaking oil up into that area??
     
  14. soccerrj88

    soccerrj88 New Member

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    What do I use to make another exhaust gasket that will work better? Also I took it out today and took the end off the muffler just to figure out what it would do. I got the needle adjusted right, so it runs decent from idle to midrange, but WOT throttle, it just starts sputtering and loses power. I was able to do 38.6 with a 44T sprocket, but with that stutter, and a 36T it only goes 35 today. It went 40 yesterday, but it took longer with the exhaust put together..... Anyways, it accomplishes what I wanted it to do, by running slower at a faster speed.
    But in order to stop the 4cycling at WOT do I need to make the high speed jet smaller? Making it leaner?
     

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