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Thread: Questions about switching from Alky to gas

  1. #1

    Questions about switching from Alky to gas

    I'm getting an old Animal alky engine and want to switch it to run on gas for a minibike project, not for racing.
    Besides carb jets, GENERALLY what else is needed. I don't have the engine yet so I can't measure anything like squish or compression etc.
    I'm just interested in generalities right now. I can ask specific questions when they occur.
    Thank you
    Danford1

  2. #2
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    You should just have to rejet the carb and go have fun.

  3. #3
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    Calculate the area of the jets (pi R squared) and choose jets with about half the area. For instance; a .053" jet is about twice the area of a .038" jet.

    Alcohol can run with much more compression than gas, it's important that you check the compression ratio. I know you don't want to hear that, it may be difficult to check, but you asked.

    Check the ignition advance too.
    From the desk of Al Nunley 512-630-6215
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  4. #4
    Can E85 pump gas be used?
    I never had any alky engines so I have many questions.
    Been using gas engines all my life and I'm a retired old fart.
    I can measure and cc everything to figure compression, I have the tools.
    I hope to have the engine this week.

    Thanks
    Danford1

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    Quote Originally Posted by danford1 View Post
    Can E85 pump gas be used?
    I never had any alky engines so I have many questions.
    Been using gas engines all my life and I'm a retired old fart.
    I can measure and cc everything to figure compression, I have the tools.
    I hope to have the engine this week.

    Thanks
    Danford1
    85% alky, so if you jet it right, why not?
    From the desk of Al Nunley 512-630-6215
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    If the data does not support the theory, get a new theory. (Al Nunley)

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    Review the primary jet, low speed, long one. For a gas Animal, the jet should fall within the .30 to .34mm range. As for the main jet, a .93 or a .95mm jet is used in stock gas applications. Might have to find a gas needle jet (they are stamped BGB) and consider the gas fuel nozzle in the carb that's around .104 thousandths inside diameter to receive the needle jet.

    There's a chance that someone might have rotated the flywheel via an offset key to advance the ignition timing too. If yes, simply grab a stock keyway, you'll be fine.

    All of the info above is based on the assumption that carb, flywheel, head, and ignition system are stock.

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    Duplicate, sorry.

  8. #8
    Thank you for the info. I will check things out when it arrives later this week.
    I appreciate the help.
    Cheers
    Danford1

  9. #9
    4 Cycle Advanced User Jimbo's Avatar
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    One problem with E 85 is that it isn't always 85%

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    Quote Originally Posted by Jimbo View Post
    One problem with E 85 is that it isn't always 85%
    How is it that you know that?
    From the desk of Al Nunley 512-630-6215
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    If the data does not support the theory, get a new theory. (Al Nunley)

  11. #11
    4 Cycle Advanced User Jimbo's Avatar
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    E85 in the United States
    From Wikipedia, the free encyclopedia
    Main article: E85
    E85 is an abbreviation for an ethanol fuel blend of between 51% and 85% denatured ethanol fuel and gasoline or other hydrocarbon (HC) by volume.

    https://www.youtube.com/watch?v=8U0BdpljRWQ

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    Quote Originally Posted by Jimbo View Post
    E85 in the United States
    From Wikipedia, the free encyclopedia
    Main article: E85
    E85 is an abbreviation for an ethanol fuel blend of between 51% and 85% denatured ethanol fuel and gasoline or other hydrocarbon (HC) by volume.

    https://www.youtube.com/watch?v=8U0BdpljRWQ
    Thank you, I appreciate that.

    Thinking about the guy who checks his gas mileage regularly. The difference in alcohol content has got to play havoc with his calculations.

    Imagine a karter trying to get his jetting right! 50% to 85% is like a 43% increase in alcohol. That's got to play havoc with your jetting and ignition timing. lol I wonder if there's some easy and convenient way of checking the alcohol percentage?
    From the desk of Al Nunley 512-630-6215
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    Quote Originally Posted by Gonzari View Post
    Thank you, I appreciate it. karting has been doing the same test since 1977. Still, good test, but I don't think it qualifies as quick and easy. Just a judgment on my part, others might disagree.

    Some are saying that E85 alcohol content can vary by as much as 45%, do you know of any confirmation on this claim?
    From the desk of Al Nunley 512-630-6215
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  15. #15
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    There is a pro gas setup for those carbs...Steve Baker was the guy who was behind that class i believe and he could tell you what fuel to use, and what jetting to use to get the engine running best for gas

  16. #16
    Where do you guys buy your alky for racing?

    Danford1

  17. #17
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    Most fuel suppy or petrolium distributor will have it.
    Race car shops may.
    Kart shop .
    May have even seen it at a dirt bike shop.

  18. #18
    What is the proper name for it if I call and ask if they sell it?

    Thanks
    Danford1

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    A great reason to buy a hydrometer calibrated for the range you need to run.

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    Quote Originally Posted by danford1 View Post
    What is the proper name for it if I call and ask if they sell it?

    Thanks
    Danford1
    Methanol

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    Quote Originally Posted by danford1 View Post
    What is the proper name for it if I call and ask if they sell it?

    Thanks
    Danford1
    M1 Methanol or Racing Alcohol....VP M1 is what most use and sell for stockers on alcohol. Airports sometimes sell it as well, so you can check there. But most race shops will sell alcohol

  22. #22
    Thank you. I appreciate the info.

    Danford1

  23. #23
    I'm finally updating this thread.
    I received the Alky Animal.
    I bought the 3 carb jets, new, plus a BGB needle.
    I haven't had much time to play with it but I got it running.
    It runs pretty good at mid range and Wot but the idle is Super rich.
    I have the air screw (PZ carb) so far out it is ready to fall out. It idles but
    not well.
    How can I lean the idle circuit but not effect the mid range and Wot ranges?
    Hmmmm just thought of something. Do you use a different air screw when you use Alky?
    I didn't change that...

    Danford1

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    Move the needle clip to lean it

  25. #25
    I tried moving the clip down to raise the needle and it didn't help. I raised the clip to the last position to drop the needle the max and that didn't help either but gave it a slight bog, so I moved the clip down a notch and left it.

    I then tried adjusting the float level to lower the gas in the bowl. That helped the idle some. Then I tried letting it idle richly and turned off the gas. In a minute or so it started to idle much better and cleaner as the fuel level was used up. I was actually able to adjust things for a very nice smooth idle as it was running out of gas.
    My idle jet (the long skinny one) is a number 32. Is that a "rich" jet? I need something much leaner...

    Danford1

  26. #26
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    Can you just measure all the holes in the jets, e tube, nozzle and list them here. You can't go by the # stamped on the jets. Most if not all the engine builders re drill the parts to the size they want. You might be better ahead just to install a new carb and call it a day!

    Steve

  27. #27
    4 Cycle Advanced User Jimbo's Avatar
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    If you get all the slack out of the throttle cable you can adjust the idle with the brass nut on top of the carb. (Under the rubber boot)
    1. screw the brass fitting all the way down.
    2. get all the slack out of the throttle cable.
    3. put kart on stand or get the wheels off the floor (safety, in case the idle is too high when you start it)
    4. start engine and back brass nut out to increase idle.
    5. if it doesn't work you probably didn't get all the slack out of the cable. repeat step 2
    Otherwise this will help http://www.fastermotors.net/TheMissingLink.html

  28. #28
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    Quote Originally Posted by danford1 View Post
    I tried moving the clip down to raise the needle and it didn't help. I raised the clip to the last position to drop the needle the max and that didn't help either but gave it a slight bog, so I moved the clip down a notch and left it.

    I then tried adjusting the float level to lower the gas in the bowl. That helped the idle some. Then I tried letting it idle richly and turned off the gas. In a minute or so it started to idle much better and cleaner as the fuel level was used up. I was actually able to adjust things for a very nice smooth idle as it was running out of gas.
    My idle jet (the long skinny one) is a number 32. Is that a "rich" jet? I need something much leaner...

    Danford1
    yes .032 is big. Stock ones are around .014 to .016 I think. I bet that is your issue.

  29. #29
    4 Cycle Advanced User Jimbo's Avatar
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    If the idle jet is marked with #32 it means it's .32 mm which is about .011 to .012"
    If it's been drilled for alcohol it will often be much larger than that.

  30. #30
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    Darned Metric system..... Invented by the Europeans to confuse us Americans.

    I guess the point is, you need to check with pin gauges to know the real hole size. If you have metric gauges you want the hole to be close to .32mm if you have red-white and blue all American gauges you want it around .012 inches!

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