Flame thrower

On a 4 stroke.

Hook up another cdi/coil to the kill switch. If I tried this, I would use a venturi for the fuel as well as air so I could shoot fire with the engine running.

Yeah a separate air/fuel intake into the exhaust would be more effective, but more dangerous .

I was riding my 250 Yamaha Enduro to the junk yard a long time ago to fetch a drum brake and had a towel on the seat to keep the grease ect. off my bike...ANYHOW the towel caught fire and so did the seat does that count for anything as the flames were NEAR the exhaust? It was a funny sight to behold!

Oh man George! Glad ya didn't wreck.

george_n_texas said:

I was riding my 250 Yamaha Enduro to the junk yard a long time ago to fetch a drum brake and had a towel on the seat to keep the grease ect. off my bike...ANYHOW the towel caught fire and so did the seat does that count for anything as the flames were NEAR the exhaust? It was a funny sight to behold!

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Dang.

When I was riding for the first times a few years ago 150 dirt bike clutch and like 4 gears I think, tops out around 40-50 on dirt.

Was going like 45 over gravel WOT back n forth it was starting to get warm (Like to light up a towel) suddenly the I feel this cold spray and sizzling, gas was pouring all over the hot engine lool.

Holy sh!t I would be freaking out if gas started spilling like that. Did the gas tank burn through? I guess if you had the kill switch hooked up to another ignition it would be cool for when slowing down with a tailgater lol. You could engine brake to a stop with fire shooting out just like a street tuner.

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.

Actually, when down shifting some vehicles with short, non-baffled exhaust systems, like dirt bikes, you can have fire coming out. This can happen on highly modified cars as well. My idea was to have the kill switch hooked up to an extra cdi from an HT so when I am slowing down, I can engine brake and shoot fire. It wouldn't run both ignition systems at once, that would be pointless because then there would be no unburnt fuel in the exhaust.

Years ago I had flame throwers on my 1950 Mercury with an Olds rocket 88 in it. This set up got me in BIG trouble. One Saturday night as we were cruising the main drag that had only 2 stop lights on it and every farmer in the county was in town shopping cause the stores were all open on Saturday night. I was the second car back from the stop light, I revved up the engine with the clutch pushed in and let the exhaust back out through the old smitty mufflers and hit the ignighter switch. It belched out some blue flame as the exhaust cackled but I didn't see a lady walking behind the car. It curled her nylons right up to her garter belt. Old Major Jones. the local cop. was standing on the corner and took this all in. He impounded my car, and put me in jail. Went before the judge he gave me a good axx chewing and a pretty steep fine, told me I had to make restitution to the lady. I gave her a sincere apology and enough money to buy 2 months worth of nylons. She accepted and I thank God she didn't sue. I guess people weren't as sue crazy as they are now. It was a very expensive lesson.
buzzard

Found a good forum about this at http://www.mopedarmy.com/forums/read.php?1,299102

I built a few flamethrowers many years ago. They are simple in the cars, and I believe no more complicated for a bike that has a remote coil/cdi. Straight mags wouldn't work.
The key will be the switch.
Needed will be a momentary switch that has two contact sets. Normally open, and normally closed. When the switch is left alone, the power/ground/whatever that signals the coil that runs the engine is going through the normally closed contacts. When you push the button, you drop the engine ignition and fire the flamethrower ignition. It will use the same trigger system as the engine.
Open the throttle and as the engine approaches it's higher rpm you push the button, killing the primary ignition and firing the secondary "flamethrower". You hold the throttle WFO and cycle the switch, which allows for the unburnt fuel to run the flamethrower.

This will only work if the primary ignition has a trigger source that can be split. In a car, it's the ground wire between the distributor and coil. Nothing changes except for where the signal goes. I don't know how much primary voltage you have with a CDI, but if it is not too much to short within the switch, you should be able to do it quite easily.

BTW. I've never heard of any type of engine problems associated with flamethrowers, but a few mufflers have suffered.

Greybeard said:

I built a few flamethrowers many years ago. They are simple in the cars, and I believe no more complicated for a bike that has a remote coil/cdi. Straight mags wouldn't work.
The key will be the switch.
Needed will be a momentary switch that has two contact sets. Normally open, and normally closed. When the switch is left alone, the power/ground/whatever that signals the coil that runs the engine is going through the normally closed contacts. When you push the button, you drop the engine ignition and fire the flamethrower ignition. It will use the same trigger system as the engine.
Open the throttle and as the engine approaches it's higher rpm you push the button, killing the primary ignition and firing the secondary "flamethrower". You hold the throttle WFO and cycle the switch, which allows for the unburnt fuel to run the flamethrower.

This will only work if the primary ignition has a trigger source that can be split. In a car, it's the ground wire between the distributor and coil. Nothing changes except for where the signal goes. I don't know how much primary voltage you have with a CDI, but if it is not too much to short within the switch, you should be able to do it quite easily.

BTW. I've never heard of any type of engine problems associated with flamethrowers, but a few mufflers have suffered.

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yes, that's exactly how a flame thrower kit works that you can buy for a car.

yes, there have been engine troubles related to this type of flame thrower.
when you use it, you're washing the cylinder(s) down with raw gas which washes oil away.
it can wear out a set of rings in no time.
This happened to a friend of mine who had flame throwers on a 53 chevy.
a brand new crate engine lasted one year after him using the flame thrower as often as he could.
the failure was the rings, and after about 6 months of using the flame thrower, it started to burn oil really bad and it lost compression.
he pretty much killed a brand new engine in less than 12 months from using a flame thrower of this style.
I had one on my 55 for awhile, but i took it off after he found out that his engine was toast.

dragray said:

yes, that's exactly how a flame thrower kit works that you can buy for a car.

yes, there have been engine troubles related to this type of flame thrower.
when you use it, you're washing the cylinder(s) down with raw gas which washes oil away.
it can wear out a set of rings in no time.
This happened to a friend of mine who had flame throwers on a 53 chevy.
a brand new crate engine lasted one year after him using the flame thrower as often as he could.
the failure was the rings, and after about 6 months of using the flame thrower, it started to burn oil really bad and it lost compression.
he pretty much killed a brand new engine in less than 12 months from using a flame thrower of this style.
I had one on my 55 for awhile, but i took it off after he found out that his engine was toast.

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I believe that your friend had more of an issue than just using the flamethrower.

When using a flamethrower the first 2 cycles, intake and compression strokes, are exactly the same as if ithe engine was running. The charge temps rise dramatically when the charge is compressed, and the mixture becomes a gas rather than the great solvent it normally is. It doesnt wash the cylinder down in that state. Even if the changing from liquid didn't occur, the washing of the cylinder walls could only be doubled from "normal" operation.

A 4stroke engine has oil rings who's job is to scrap the oil off the cylinder walls to keep it from being burned.
A 2 stroke however, has no oil rings and the intake charge contains the same amount of oil as was in fuel/oil mix, making what happened to your friend a mute point in their case.

Greybeard said:

I believe that your friend had more of an issue than just using the flamethrower.

When using a flamethrower the first 2 cycles, intake and compression strokes, are exactly the same as if ithe engine was running. The charge temps rise dramatically when the charge is compressed, and the mixture becomes a gas rather than the great solvent it normally is. It doesnt wash the cylinder down in that state. Even if the changing from liquid didn't occur, the washing of the cylinder walls could only be doubled from "normal" operation.

A 4stroke engine has oil rings who's job is to scrap the oil off the cylinder walls to keep it from being burned.
A 2 stroke however, has no oil rings and the intake charge contains the same amount of oil as was in fuel/oil mix, making what happened to your friend a mute point in their case.

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why is it that whenever someone posts something about a problem, there's always someone who has to come back and say "no, you're wrong!"

you don't have to explain to me how 4 cycle engine works.
I've been there and done it all from building stock engines, to all out drag engines. I've been custom car and motorcycle builder for 25 of my 43 years.
ive been through it all and i know what i'm talking about.

the proof was in the disassembly of his engine.
it was a brand new G.M. crate 350 and within 12 months, the rings were toast (including the oil rings)due to the cylinders being washed down with raw gasoline every time he used the flame thrower. G.M would not warranty this because they deemed it abuse. the engine came with a 36 month 100,000 mile warranty and at the time it started burning oil, it had 5,000 miles on it.

so, beleive what you want.

cranking over a engine thats not firing is not going to wash the cylinder walls of oil, unless it was hellishly flooded with fuel from a stuck float or some other problem which cause raw fuel to pour into the cylinder. and in that case your going to have to crank it over any ways to clear out the cylinder. chances are your friend there failed to properly break in his new crate motor and it accelerated ring wear.

moonerdizzle said:

cranking over a engine thats not firing is not going to wash the cylinder walls of oil, unless it was hellishly flooded with fuel from a stuck float or some other problem which cause raw fuel to pour into the cylinder. and in that case your going to have to crank it over any ways to clear out the cylinder. chances are your friend there failed to properly break in his new crate motor and it accelerated ring wear.

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ok then...look it up if you don't beleive me.
it is a known fact that unburned fuel can make it past the rings, wash down the cyulinders and end up diluting the engine oil.
when an engine is running, the spark plugs burn the air-fuel mix before it can make it past the rings.
when you're dumong raw fuel into the cylinders, most of it is pushed out through the exhaust vales and into the exhaust pipe.
a risidual amount can and will seep past the rings and wash the oil off of the cylinder walls, which makes metal to metal contact between the cylinder walls and the rings.
doing this A LOT will eventually cause ring failure, and gasoline in the oil isn't good for the bearings (on a 4 cycle engine).

as for my friend not breaking in his engine properly, he followed the reccomended break in procedure as per G.M. AND the instructions that were given to him by the dealer where he bought the engine.
he put the flame throwers on his car after the engine break in period.

could this have been a fluke? sure it could have been, but i know a lot of people with flame throwers in their exhaust, and every one of those engines started to burn oil shortly after the flame throwers were installed.
I had flame throwers on my 55 pontiac for awhile, and i noticed that the oil reeked of gasoline after using them oonly a few times.
once i stopped using them, the oil no longer smelled like gas....so you tell me, why is that?

but what do i know? everyone seems to have an opinion without any proof.

Well one thing's for sure if all someone cares about is havin a flame thrower they must not be havin problems with the chain comin off...finished porting their HT...tuned their poo pipe...installed a nitro kit...ran christmas tree lights off the white 6v wire just to show it can be done...got tired of playing with Richie Rich...you get the picture LOL

Beem me up Scottie there's no intelligent life forms here...

If I was calling the shots on honoring an engine warranty, and "flame throwers" were mentioned, that would be the end of story, regardless of the reason for failure.

I knew a guy that set up a windshield washer pump that pumped Automatic Transmission Fluid into his intake manifold, "james bond smoke screen"

I dunno what it did to his engine tho, it seemed to run fine