Help with Science Experiment

Discussion in 'Motorized Bicycle General Discussion' started by Lachiepower0402, Jun 17, 2014.

  1. Lachiepower0402

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    Hi everyone,

    I am thinking of doing a science experiment for a assignment to test which spark gives the fastest speed on a motorised bikes, can anyone give me a list of spark plugs to test. I already have a NGK-B6HS and the stock spark plug.

    My bike is a 48cc china girl

    Regards,
    Lachiepower0402
     
  2. mapbike

    mapbike Active Member

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    You wont likely see any speed gains from one plug to another Lachiepower0402, the spark plug probably effects speed and power the least of all the other components of the China girl engine.

    Do the experiment using different amounts of exhaust restriction or different size rear sprockets for showing how different gear ratios affect top speed.

    Changing spark plugs will most likely not show you any changes in top speeds.

    Best wishes of the experimenting

    map
     
  3. Davezilla

    Davezilla New Member

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    True... unless you're using a really badly worn spark plug and comparing it to a new one, but that'll still only effect overall performance (how well it runs) more than speed (how fast it runs).
    I'd run the experiment on something else as well, gear ratios or exhaust pipes or mufflers may give you better more noticeable results to record for your testing.
     
  4. 2door

    2door Moderator
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    If the plug is meant for the engine it doesn't make any difference who made it or how much it costs. If it fires when its told to the engine will run the same, and produce the same power, hence the same top speed.

    Look for a better way to compare things. Spark plugs aren't going to tell you much.

    Tom
     
  5. wheelbender6

    wheelbender6 Active Member

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    Do the experiment with different fuels. Measure the performance running alcohol, regular and high test.
     
  6. Theon

    Theon New Member

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    Different plugs may make the engine a little easier to start, different heat ranges will likely effect the running temperature of the motor. But I agree your unlikely to notice much difference in top speed.
     
  7. apex

    apex Member

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    Timing advance and octane will have a far greater effect on when spark occurs and flame front speed than plug variances.
     
  8. Lachiepower0402

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    The idea of changing the fuel to a different octane or different fuel altogether like alcohol sounds alright.

    What exactly would be the difference with the exhaust, wouldn't the speed be slower with a smaller muffler manifold.

    I would also consider doing the sprocket experiment but then I would have to cut my chain and I don't have the right tools for that and I but cut it to short for what I need it for normally.
     
  9. mapbike

    mapbike Active Member

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    I'd stay away from running alcohol wnd honestly different octane fuels arent gonna do much either.

    Yes restricting exhaust flow lowers top speed and overall power for that matter, if you have a stock type muffler, just go to yout local doller general or simular cheapy stuff store and buy a couple packs of stainless steel or copper scouring pads, remove end cap from exhaust and put one of the pads in the muffler reinstsll the cap and run to see what you top speed is with the one pad which will restrict flow a little then repeat the process with two pads and test, then do it again with three pads and test speed again, then maybe leave end cap off for the final run and see how the different amounts of restricted flow affects each top speed run.

    That will be a simple, cheap and fun experiment for you and will not require you to make any major modifications to the engine, bike or any other of its components.

    Thats what I would do and just log all the results.

    Map
     
    #9 mapbike, Jun 18, 2014
    Last edited: Jun 18, 2014
  10. Goat Herder

    Goat Herder Gutter Rider

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    Wanna say to the op.
    From what I have seen on a two smoke. It had better be the dead of winter and cold as heck outside. Too cold to ride lol. Then its safe enough to take a peek..Still have to know what you are doing.

    Not a good experiment for some newbees. I just wanna say Danger Will Robinson. Danger!!

    IMO one needs to understand what a good plug chop is. Also that can still fool some one. These two strokes just are not tamable in this regard. Timing advance is a good way to be doing a jug overhaul! All it takes is a couple of hotrodding miles.


    Check out gears. This can teach you a bit about where your power band is, and with how the engine goes.

    Learn tuning and maintenance.

    Then after keeping things simple try a tuned pipe. Then mebbe port match, bigger carby.


    Basically this said science wanna say keep things simple. Try things in stages and paying attention to detail will be the best base line ever. Then science can evolve a bit toward some mad science lol
     
  11. mapbike

    mapbike Active Member

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    What you said here GH is exactly why I made the suggestion I did about tinkering with exhaust back pressure, its simple, cheap and runs less risk of damaging the engine, if the fella doesnt have the tools he needs to swap chains and gears, Im gonna say he is pretty limited on what actual experiments can be done, exhaust mods like I mentioned are sime and each change will show a difference in performance, I've messed with this stuff in the past and just figures keeping it a very inexpensive and easy task is what would aply the best here.

    Just my $0.02 here though.

    Map
     
  12. apex

    apex Member

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    I wasn't reccomending a different fuel or timing change, I was simply stating that different plugs will not change when ignition occurs(timing) or how fast the fuel burns (octane).
     
    #12 apex, Jun 18, 2014
    Last edited: Jun 18, 2014
  13. Lachiepower0402

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    That idea sounds really good indeed. I will be using it for my experiment.

    How would you reckon I would test my top speed because my teacher is picky and I will have to write down how I reach my top speed do I just run it for 10mins.

    Also I have to take into consideration things like the engine being hotter the second time I run it and performing better

    Regards,
    Lachlan Fullagar
     
    #13 Lachiepower0402, Jun 19, 2014
    Last edited: Jun 19, 2014
  14. Davezilla

    Davezilla New Member

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    best way for the actual testing is to either do all testing with a fully warmed up engine or let it cool all the way down then run it for a specefied amount of time to wram up then test for each test run, of course, if you don't have time to fully cool the engine between runs, you'll need to pre run it to get the engine all the way up to temperature before the first run, maybe ride it hard for about 5 to 10 minutes before the first test.
     
  15. Lachiepower0402

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    That sounds alright. But my science teacher says that she would't let me put anything in my exhaust for the experiment because she is worried that it will blow the engine, what can I say to say it won't do that. She said I could just test it just with the cap on and the cap off.
     
  16. xseler

    xseler Well-Known Member

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    I've had a scouring pad in my home-made exhaust for the past several hundred miles --- zero issues.

    [​IMG]

    I drilled a hole through the end of the muffler to insert a wire to secure the scrubber ---- the exhaust is strong enough to blow it outa the muffler! I can't tell that it hinders performance, but it certainly mellows the exhaust tone.

    Good luck with your project!!
     
  17. Theon

    Theon New Member

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    There's probably other things you can do with regard to modifying the inside length of the final tube, drilling baffle holes in it, crimping the inside end after drilling baffle holes and maybe 'butchering' one while keeping the other to test your changes.
     
  18. xseler

    xseler Well-Known Member

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    I think I still have a stock muffler end cap if you need one to 'experiment' on. Gratis, just pm me your addy.
     
  19. Davezilla

    Davezilla New Member

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    If you had an expansion chamber pipe... make that 2 of them, perfectly identical except one you leave stock and without a muffler, the second one you use without a muffler too, but you weld shut the stinger outlet and make an outlet from the side of the belly section at it's widest point and weld in a stinger pipe for the exhaust to get out, the difference will be that the side bleed setup will be considerably quieter, even without a muffler.

    I don't know if you're able to get these parts or to do the welding, but it would make for a good experiment as you end up with a much quieter ride with no change in performance.
     
  20. mapbike

    mapbike Active Member

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    Putting scouring pads in the stock muffler can't in any way create an issue that would cause the engine to "blow up" adding the pads will actually restrict flow and restrict rpms which will bring the top speed dow, removing the end cap works the opposite and will allow engine to rev higher which will most likey give you your highest top speed.

    Map
     

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