Shooting flames out exhaust...! 🔥

[RB55]

Neat but someone will call the fire Dept driving down the street.

Luckily I live pretty far out, so I rarely pass by any houses or people on my daily ride route. That would make for a good news article though

 

[Sumsloppymeet]

I agree flames have a mind of their own make sure your not leaking fuel like ever or this may be a result lol

 

[Vikingimike01]

It also decreases performance. Not noticably though I belive.

 

[RB55]

Wouldn't the combustion still be happening in the pipe then? So as the exhaust opens the flame goes back up into the chamber, through the transfers and into the case?

A one way valve past the header would might work, some kind of pulse jet inlet design

Neat build idea but it worry's me.

With his setup, I believe that the flame could potentially travel back into the combustion chamber since the ignition occurs somewhere farther up in the exhaust. I don’t think this would hurt the engine, however, since the the combustion chamber/jug is supposed to withstand a nearly constant cycle of combustion...the only issue I could see is the flame somehow traveling back into the carb and setting the gas there on fire.
In my setup, all ignition of the unburnt gas occurs at the end of the exhaust pipe. This definitely heats it up and may add some back pressure to the engine/exhaust system, but the flame can never travel back into the engine.

 

[RB55]

Update - taser and bbq electrode came in today. The taser seems to work well, but I’m going to remove the stock battery and hook up the input to a custom 10,000 mah USB power bank my headlights run off of. Picked up a boost converter as well in case the voltages aren’t identical. I’m going to use JB weld high-heat epoxy to attach the bbq electrode to the exhaust and bend it so it’s centered in the tube. Negative will hook up to the inside of the tube so the spark will jump inside. Also tested out a 12$ analog tach from Amazon - took a while to figure out the wiring but it works decently for the price. It’s very accurate but the needle is a little lazy and so it takes a while to reach the actual RPM of the engine. But at least the concept is valid, someday I’ll get a high quality 10K rpm tach and wire it up to get a real tach experience. It’s already useful even on this fixed gear bike to know what RPM to rev the engine to before you engage the clutch downhill and also to stop your RPMs from going too high which is bad for the engine.

I’ll post pictures and videos as the project continues.

 

[RB55]

Update 12/18/19 - been waiting for parts to come in forever and finals in school are taking up most of the afternoon. Finally got around to working on it for the last few days. A LOT of soldering has been involved and tons of wires to get everything ready. I took apart the taser and isolated the high voltage module, which produces a strong ~1cm spark at 7 - ??? volts (don't want to blow it!). Also I wired up two boost converters to my USB power bank (5V) I originally got for my headlight and to charge my phone: one for my eBay $12 analog tachometer (which works! tested tonight after 3 hours of soldering) @ 12.5V and the other for the taser @ 7.5V. I can adjust it to make a stronger spark if needed. Also picked up a toggle switch to finish the system off. I already found a good spot to mount the high voltage module and am ready to roll. Tomorrow I'm going to repack and reassemble my exhaust muffler, seal all connections, and in the process hopefully find somewhere to mount up the BBQ electrode so it sticks inside of the exhaust without any metal touching the electrode tip. Then wait for JB weld high heat and high temp gasket maker to cure overnight and Friday it should be ready to go! I'll post pictures when it's all done.