exhaust flame thrower

Could I make a simple exhaust flame thrower for my mini bike without a
$100 kit? I'm thinking of just putting in an SPDT momentary rocker
switch (if there is such a thing) that can redirect the electricity
from the engine to a spark plug in the exhaust. The kind of switch I
would need would be switch that is always on in one setting and then
springs back after I press it to a different setting. Do they make
these?

on (except when pressed)

--------------_____------(> engine spark plug
switch -------(> exhaust spak plug

momentary



If that makes any sense.

 

Do a search for a SPDT momentary contact rocker switch with a 15,000 volt
rating.

 

Are you looking for a bloody great backfire from the exhaust pipe or do you
really want a flame thrower?

R

 

you'd need a switch that can switch the thousands of volts that go to the
spark plug. you could possibly use an autombile disttributor.

you'd need to attach a lever to the input shaft to to turn it sufficiently
to switch to the other plug.

 

--Funny you should mention this. Last weekend, I think it was
on Spike TV on one of the truck shows they showed how to do this. You
might snif around over there. I'm planning something similar for an art
car project. Another place to ask would be over at tribe.net in one of
the pyro or art car tribes.

 

It's doable, BUT!

Yes, there are momentary rocker switches, but you wouldn't want SPDT,
because then your motor wouldn't fire.

But the real problem is switching the 15-25KV spark voltage. The
spark would happen in the switch. What you really need is another
coil, and a free-running sparker, that you energize with your
rocker switch.

If you haven't been an electronics nut for a year or more, then it'll
be cheaper to buy one, if you can get one for a hundred bucks.

Good Luck!
Rich

 

I sit next door to a performance shop, and if OP thinks he can do this
for less than $100.00, he's in dreamland.

Cheers!
Rich

 

Thats exactly the show I saw that set me on this path. I checked out
the kits he was talking about, there $100 daollars. That sounds like
way too much money just for a kit to divert electricity from an engine
coil to rear coils. There maust have been some sort of driver involved
with the kit, but still, it shouldn't cost that much. I saw that show
just before going to a supercross event with Bubba Stewart, Ricky
Carmichael, Jeremy McGrath, Chad Reed, every body. It was so cool.

 

Depriveing the engine of power is the only way this works. Without a
spark a perfectly measured air fuel mixture is sent through the exhaust
pipe to be burnt near the end of this journey. Your supposed to rev the
engine up to a high rpm and press the switch. Momentum will keep the
engine going long enough to get a good flame; so if you can shoot
flames for about a second to keep the engine from stalling (at least
for a minibike like mine, for a car you could go longer). I had a
course for a couple of weeks in small engines. There electrical system
works a magnet IN THE FLY WHEEL being sent past a small coil to
generate the high voltage, so yes, the first spark would be lost in the
switch but each spark after would light it up.

 

A side thought, what if youwere doing this with a v8 engine. could
power be cou to just 4 cylindars and have them pump gas while the other
four run the engine so you can get a continuos flame?

 

if OP thinks he can do this

On a 40-year-old car with a carburator and Kettering ignition
it would be duck soup.

Rig a pull-choke
(maybe $4; $0 if you have an old lawnmower for parts).
Add a 2nd ignition coil (maybe $10--less from a junkyard).
Rig a SPST switch that cuts primary juice from the main coil
and diverts it to the tailpipe coil.
(The points are hooked to both coils.)
Mount the 2nd coil near the tail pipe
so the high-voltage lead can be short.
(1 ft of used spark plug wire: $0)
(Used spark plug: $0.)

 

if the motor fires there's no fuel going into the exhaust.

Bye.
Jasen

 

If anyone not familiar with this device is interested in seeing and
hearing it in action, go to this web site: http://www.flamekitz.com//

 

I used to think that putting a 4-inch exhaust cap on 1.5-inch pipes from
a 1.6 liter engine was the epitome of mental retardation, but at least
that wasn't dangerous.

I nearly choked on my lunch seeing the photos of that miserable Honda
Civic. Not satisfied with merely installing fart cans, these "gearheads"
are now LIGHTING the farts.

The first time someone singes my grille, I'm ramming.

 

But why do you want to cut the juice to the motor coil? You
want your motor to quit while you're trying to blow flames
with its exhaust?

Thanks,
Rich

 

why do you want to cut the juice to the [engine's] coil?

Yup.
Someone else already mentioned rotational inertia.
(Actually, you don't push in the clutch.)
You want the fuel/air to get thru the engine UNBURNED.

 

Precisely. If the OP's mini-bike has a carburetor and an engine kill
switch, he needs no mods. While riding, kill the ignition for a
second or two, blip the throttle, and re-engage the ignition. Kaboom!
Now of course, the reduced lifetime of the exhaust system must be
considered as part of the overall cost.

 

Yeah, you can put another coil and spark plug in the exhaust, but that
will do squat. The exhaust is hot enough to ignite combustible
material without a spark helper - the spark would really have little
effect at all. What you need is unburned fuel in the exhaust.

Probably (I'm guessing here) the flame-thrower show mods are a fuel
sender to a combustion chamber attached to the exhaust. Separate fuel
lines, separate coil, separate fuel injection system. Hunnert bucks,
yeah, that oughtta do it!

 

Ramming is soooo immature. Sue the bastards.

 

I've seen these - right next door, there's a "performance shop", and
I occasionally see this very thing on some show car or another.

I think "a hunnert bucks" will get you about 1/8 of the system or so. ;-)

Thanks,
Rich