Flex Pipe Exhaust

[Hot Wheels]

HI ALL, I'VE SEEN PICTURES OF BIKES WITH FLEX PIPE EXHAUSTS, WHAT IS THE PIPE, IT SEEMS TO BE GAS PIPE. AND ALSO HOW DO YOU PUT A FLANGE ON IT, IS IT A FLANGE WELDED TO A PIPE THAT WILL SLIDE INSIDE THE FLEX PIPE? I APPRECIATE ANY REPLIES AND OR PICTURES,.

 

[2door]

Flex pipe made for natural gas or even propane will work. Don't try electrical flex conduit. It will leak...and I mean leak. If you're a welder and can do thin stuff you can weld the flange to the flex or a short section of your stock exhaust pipe into the flex.
A better option is to use electrical conduit, called EMT. It can be bent with a conduit bender and welded to the flange and muffler to make any length/shape pipe you desire.
Tom

 

[K.i.p]

I used flex pipe for natural gas line. The bends one can get with this stuff is phenominal and has EMT beat hands down. My build has two very tight bends that would have been imposable with conduit and I bent it with nothing more than a pair of gloves and a solid floor. The pipe itself is stainless.

The down side is that this stuff is crazy expensive. If you plan to purchase it you'll probably have to buy a length that will make it uneconomical and wasteful. I was lucky enough to have an inside line with someone in the field.

I respectfully disagree with 2door on the fabrication aproach. I did little or no work on the flex pipe but rather performed the fitting work on the solid pipes. You will likely need some machine skills or know somebody that can. I turned some fittings to fit the I.D. of the flex pipe and brazed these to the exhuast manifold, and straight exhuast run.

The biggest hurdle was the clamping issue. After some prototyping with avaialable clamps I found it necessary to make my own. The clamps themselves where machined to match the corigated form of the flex pipe. I made a single curf in the flex pipe applied liberal amounts of high temp RTV and tightend my clamps, sealed and solid.

All told it was a lot of work that required some trade skills. To me it was worth it to build something "not like the other guy's".

 

[Hot Wheels]

Thank You So Much For Your Replies, I Will Try To Make My Exhaust This Weekend. Thanks Again.

 

[2door]

I respectfully disagree with 2door on the fabrication aproach. I did little or no work on the flex pipe but rather performed the fitting work on the solid pipes. You will likely need some machine skills or know somebody that can. I turned some fittings to fit the I.D. of the flex pipe and brazed these to the exhuast manifold, and straight exhuast run.

KIP,
I'm not sure I see where you're disagreeing with me. You did exactly what I suggested by making/welding fittings to the flex. I will say that conduit can be bent in a tighter radius than a conduit bender will do...with some cheating. If I'm bending 3/4" I'll use a 1/2" bender and keep moving the pipe along to shorten the radius. It takes some patients but it does work. And, if you're careful you can even keep from kinking or denting the pipe. Here's a couple of examples that I've done.
Tom

 

[restapukin]

Nice photo's.... sir you are an artistic engineer or an engineering artist

or something.

 

[K.i.p]

I didn't braze or weld anything to the flex. And I didn't make any fittings to weld or braze to the flex. The adaptors where brazed to solid pipe, and actually to a muffler. The Flex is slid over and clamped in place. Just a minor technical misunderstanding. Also the bends obtainable with flex can actually be taken beyond ninety into acute angles although that is not practical for exhaust applications. No bender required.

 

[2door]

I didn't braze or weld anything to the flex. And I didn't make any fittings to weld or braze to the flex. The adaptors where brazed to solid pipe, and actually to a muffler. The Flex is slid over and clamped in place. Just a minor technical misunderstanding. Also the bends obtainable with flex can actually be taken beyond ninety into acute angles although that is not practical for exhaust applications. No bender required.

k.i.p,
I like your idea of putting the exhaust out to the right side. I bent a pipe to do that on one of my bikes, still have it, but at the last minute I went back to the old route. I want to experiment with a dual exhaust, one on each side, split at the header on the cylinder....maybe a spring project. That one photo I posted shows an explosion proof electrical conduit fitting that I used to make the pipe removable without disturbing the flange gasket at the engine. I fabbed an adapter with a flange and a male threaded piece that bolts to the cylinder and attaches to the pipe with the nut.
Tom

 

[K.i.p]

Hey Tom,
Nice stuff! Believe me I appreciate your skill as well as your contributions here, and I really meant "respectfully" disagree. I am still relatively new to all of this but have a fairly well rounded background in the machine and tool trade. I would be lost without it!

I had disassembly in mind as well. If I had a really good skill level in tube bending I might have opted for working with solid tube but it was out of my depth and I needed to swing that exhaust run as tightly as possible. It's no coincidence that most of the motorized elements are located towards the right. The side exposed towards traffic is very simple and almost unnoticeable between my legs (NY here).

I'm curious about different exhaust approaches, it would be fun to see what you might come up with concerning a duel exhaust. And I would be interested in it's effectiveness. The guys at the shop where pretty impressed by how quiet this double muffler set up is on mine. It's not crisp or snotty but that is not what I wanted anyhow. I just want to be able to take some spins around the neighborhood from time to time without upsetting people or facing the wrath of john law.

 

[TurboNegro54]

Nice work dude

 

[Hot Wheels]

I LOVE SEEING SO MANY TALENTED AND CREATIVE PEOPLE, I REALLY LIKE TO SEE ALL THE DIFFERENT WAYS TO DO THINGS. HERE'S A PICTURE OF MY FIRST EXHAUST MADE WITH CONDUIT WITH DUEL MUFFLERS, IT SOUNDS SO COOL.

 

[Dan]

Purty work Hot Wheels! Great tank too. Wan't to do a similar thing so if you have or ever do post a thread on your build, please lemme know. Looks great

 

[Hot Wheels]

Purty work Hot Wheels! Great tank too. Wan't to do a similar thing so if you have or ever do post a thread on your build, please lemme know. Looks great

THANKS DAN. I WILL LET YOU KNOW WHEN I DO A THREAD ON THAT BIKE. I'M NOW BUILDING MY FIFTH BIKE.

 

[Dan]

Awesome, TY.

I have been working on a thing. An expanding, expansion muffler chamber. It makes the engine pulsing make a "PUTT- PUTT" old world engine sound. is really cool!

Couldn't agree with you more. Is great to see all the innovation and good cheer of the comradery here

 

[corgi1]

That is a really good lookin' MB ,love the tank and exhaust

 

[K.i.p]

Hot-W, that duel set up is pretty cool! And nice ride as well.

 

[Hot Wheels]

THANK FOR ALL YOUR COMPLEMENTS ON MY BIKE. LAST WEEKEND I BOUGHT ANOTHER JAG OFF CRAIGS LIST FOR $50.00 IT WAS NEVER RIDING, I GOT THE SPOOKY TOOTH 4G 4 STROKE. CAN'T WAIT TO SEE HOW IT RUNS. THAT'S WHY I STARTED THIS THREAD I LIKE THE LOOK OF THE FLEX PIPE EXHAUST AND I WANTED TO KNOW WHAT AND HOW THEY MADE IT. I WILL POST SOME PIC'S SOON. HAVE FUN RIDING ! ! !

 

[Hot Wheels]

I got my new Jag running, It runs real go very smooth. I did use flex pipe, I put it on the pipe coming off the stock muffler, just to run it under the bike and the motor seems to like a little more back pressure. here's a link to youtube to see it run on my stand. YouTube - new 4 sroke bicycle

 

[2door]

Very cool, Wheels.
Those Jags lend themselves to almost anything. Your looks great. Good work. How's it run?
Tom

 

[Dan]

Suweet! Pretty work HW! Love the sound.

In the great words of Sir Elton; "2 sounds that I really like..." One of them is a well tuned Motor Bike.

Noticed your wheel is perfectly trued. Good job