lol you guys crack me up...like a street tuner.
you think that's real? it's all in the movies man.
in order to shoot flames out of the exhaust (other than by the engine backfiring) is to have a flame thrower kit.
you have to have a coil and something to pulse the spark (like a magneto or a distributor.)
you have to kill the engine so raw gas goes into the cylinder(s) and is forced out the exhaust by the piston(s). the spark plug in the exhaust will ignite the raw fuel but the spark plug has to have a way to pulse just like it does when it's in the engine.
just hooking an extra cdi up won't work because as soon as you kill the engine to get raw gas into the cylinder, the extra cdi wil not fire. On top of that, the magneto may not have enough power to fire 2 plugs, and this extra plug in the exhaust would be firing while you ride....which will rob power from the engine spark plug and steal performance.
you can't just hook up a spark plug to the exhaust....it has to be hooked to a separate ignition system that works opposite from the engine ignition, you have to be able to switch back & forth from the engine ignition to the flame thrower ignition.
here's my car.
here's an idea that i came up with.
hook up a propane injection set up which would be EASY to do.
you'd need a small propane canister(like for a propane torch or a coleman grill.) you'd need the on -off valve from the torch and/or the grill to regulate the flow of propane. you'd have to run a line into the exhaust...a VERY small line with a nozzle on the end of it.
then, you could use a bbq grill electronic ignitor that's battery powered....the spark from them pulse like crazy and they have a lot of punch.
wire up the ignitor with a button on the handlebars, hook up the propane tank so that the on-off valve is easily accessable. open the propane, push the bbq grill ignitor button a VOOOOOM! instant propane flames.
but, you would have to close the propane valve to stop the flames once they start because the propane woudl be flowing constantly. It is possible that the exhaust would blow the flames out, but i don't think there's enough exhaust flow. This is just an idea, i've never tried it....but i'm pretty sure that it can be done, altho, if you have no idea what you're doing, it could be very dangerous.This is an idea that i came up with, but has never been tested. if anyone attempts this, I am not responsible.
a little propane will make a HUGE fireball. you'd have to experiment with a nozzle for the propane.