Required exhaust temperature for backfire.

Discussion in 'Motorized Bicycle General Discussion' started by fdnjj6, Sep 11, 2019.

  1. fdnjj6

    fdnjj6 New Member

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    Hello everyone. I have a question that I can only find little info about. My bike currently shoots flames out of the exhaust when I hold the kill switch while going above 10 mph and the clutch engaged. It does this because I put a bbq igniter in the exhuast. Problem is that this makes awesome flames, but no pops or bangs. I want pops and bangs. Cooter's Carport (a youtube channel) got his bike to shoot flames with pops and bangs by overheating his motor and therefore greatly increasing the exhaust temperature. Since his bike is purposefully overheated, his bikes don't last long. I want to have my exhaust hot enough to pop without killing my engine. I read online the ignition temp of gasoline is about 536-575 F. My exhaust hasn't gotten that hot according to my infrared thermometer. What temperature should my bike start backfiring at with pops and bangs? I'm guessing if I got the exhaust to be 600F I would be fine. Right? Any suggestions on how I could get it that hot? I have thought about wrapping my exhaust and making the diameter of the pipe smaller but that's about it for practical methods of getting it hot. Any help or suggestions is always appreciated. Thank you.
     
  2. fdnjj6

    fdnjj6 New Member

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    I think a picture to see the exhaust set up shouldn't hurt.
     

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  3. Jimmy Bloodmaker

    Jimmy Bloodmaker Active Member

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    wrap it super tight in pipe wrap. i've used it to extend the range of pipes a few hundred more rpms, it increases the EGT allowing just a slightly faster wave to keep pushing just a bit more. or you can retard the timing and fire just after top dead center for flames out the back, will really heat up the pipe ( glowing red) as the rpms build.
     
  4. fdnjj6

    fdnjj6 New Member

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    Hey it's you again. Lol thanks for the help. I think I'll definitely try wrapping it. Do you know how much it increased the temperature of the pipe? Any tips on how to retard the timing without moving the magnet? Could I electronically retard it?
     
  5. Jimmy Bloodmaker

    Jimmy Bloodmaker Active Member

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    there is a whole bunch in the forums on cdi's and adjustable magnets and stator coils. i've read through a lot of it. most of the electronics are pretty simple. a bunch of schematics too. you can get half keys or make your own, all kinds of ways to get what you want. there is this guy drinks a bunch of whiskey and plays with small engines on youtube. i like that guys channel. lol. he has an ep where he makes a disk for a hall sensor to run a scooter ignition system. he could adjust the timing to whatever he wanted.

    oh and as for the pipe temp, idk, i got maybe 200-300 rpms out of it, i don't remember at this moment. if i wrapped a few exposed parts i could probably get maybe 500 more rpms.
     
  6. fdnjj6

    fdnjj6 New Member

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    Thanks for the info on the pipe. I have known about adjustable magnets but that would mess with my timing throughout the whole powerband since it's fixed and would require dissassembly when I want to ride normally. I have made my own woodruff keys and did manage to change the timing, but like I said it's fixed. I'm hoping to get adjustable timing with a flame thrower mode and performance mode. I think I'll go for the electronic approach which you mentioned. I know who you're talking about. His name is 2 strokestuffing. I watch him frequently too. I think I'll go with his approach with a hall sensor. It'll probably be the easiest and most reliable approach. Thanks for the help. This stuff should keep me busy for a while.
     
  7. Jimmy Bloodmaker

    Jimmy Bloodmaker Active Member

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    yeah, thats him. good channel. lol.
     

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