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Author Topic: Tell me about 2 stroke pipes  (Read 8399 times)

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Offline beaner

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Tell me about 2 stroke pipes
« on: July 30, 2012, 11:49:19 PM »
Not so much looking for strict theory, or to do a bunch of math as much as I'm looking for a little practical info. My vintage bike (as well as most vintage bikes) has a not so great looking pipe on it. I was thinking of either building something (that's when I'll get into the theory), or adapting a pipe from another bike to see what happens.
Next season I may run an even older bike, and those pipes look just plain awful.

Just wondering if anybody here has done something similar, has any pipe building experience, or knows of any custom pipe builders that aren't ridiculously expensive.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Tell me about 2 stroke pipes
« Reply #1 on: July 30, 2012, 11:58:21 PM »
I built my own tail pipe out of sheet metal, but it wasn't designed for anything but to be obnoxiously loud, I had a bet with my friend who had a 250f that my bike could be louder, and it was. But, I'm thinking your talking your talking about the expansion chamber part of the pipe. All I know about those is that the shape they are made in is so that unburned fuel can be sucked back into the engine through the exhaust port, the way the pipe is shaped makes the energy expand in the middle and then some of it bounces back, so to speak, at the end where it tapers off. Each bike pipe may be built a specific way for the engine, so I can't help you there.

This is basically what I said, but in a video kind of thing: http://en.wikipedia.org/wiki/Expansion_chamber
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Jeram

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Tell me about 2 stroke pipes
« Reply #2 on: July 31, 2012, 12:28:11 AM »
you will need the following...

-expensive 2T software, or someone with the software who can give you a pipe spec

-lots of tools for cutting and forming the cone sections (tin snips, sheet metal rollers, cone mandrels, hammers etc etc etc

-great welding skills

-cone unfolding software

-lots of time, because your first few attempts will suck.

(I don't make my pipes, I dont have many of the above items, but I've watched it being done)



a custom one off pipe will likely cost you around $500 depending on who makes it for you
cheaper to cut and shut a pipe from another model if you find one that will definitely work, but it wont look as good or go as fast as a well made cone pipe.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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Tell me about 2 stroke pipes
« Reply #3 on: July 31, 2012, 02:55:38 AM »
Hey Beaner, as you probably know, there's oodles of aftermarket companies (and guys) making pipes for vintage and evolution class bikes. Check with DG as I've heard they are still busy making a lot of chambers.

I once adapted the stock pipe from a bike whose power delivery sucked (RMX) to a bike with a beautiful power delivery (GS6 Sachs special) and the results were the exact same gutless powerband, strange. I've made more then a few pipes, some worked very well and others with bizarre, two stage powerbands (oh well, back to the drawing board). ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline beaner

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Tell me about 2 stroke pipes
« Reply #4 on: July 31, 2012, 03:03:08 AM »
I'm just doing a little digging here. Thought some of you guys might have made some pipes, or have some past knowledge. I can fab, that's no problem.
If you have any contacts, or know any people or places still making pipes, let m know. I did a search a little while ago, abut didn't ending finding much.
I don't think it would be too hard to improve on an old Can-am TNT up pipe.  ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Jeram

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Tell me about 2 stroke pipes
« Reply #5 on: July 31, 2012, 07:48:44 AM »
theres a few guys on here who design and make pipes
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Offline 2T Institute

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Tell me about 2 stroke pipes
« Reply #6 on: July 31, 2012, 10:13:58 AM »
Last count I have made something like 80-90 pipes. First is mass market aftermarket are pretty crap there is precious little time put into the design and most don't fall into the basic pipe parameters. DG would be bottom of the pile especialy vmx stuff.
I've also coached a few people on making pipes and as I say at the beginning if you start then be prepared to have at least the cost of a really good bike tied up in tooling. One thing to design the perfect pipe next is to get it to fit on the bike, up pipes are the hardest by far.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TotalNZ

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Tell me about 2 stroke pipes
« Reply #7 on: July 31, 2012, 10:33:44 AM »
Quote from: cnrcpla on July 31, 2012, 06:58:21 AM
I built my own tail pipe out of sheet metal, but it wasn't designed for anything but to be obnoxiously loud, I had a bet with my friend who had a 250f that my bike could be louder, and it was. But, I'm thinking your talking your talking about the expansion chamber part of the pipe. All I know about those is that the shape they are made in is so that unburned fuel can be sucked back into the engine through the exhaust port, the way the pipe is shaped makes the energy expand in the middle and then some of it bounces back, so to speak, at the end where it tapers off. Each bike pipe may be built a specific way for the engine, so I can't help you there.

This is basically what I said, but in a video kind of thing: http://en.wikipedia.org/wiki/Expansion_chamber
Why would you want your bike to be loud, louder than a four stroke of all things. loud bikes are ruining our sport.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline VintageBlueSmoke

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Tell me about 2 stroke pipes
« Reply #8 on: July 31, 2012, 01:04:08 PM »
2-stroke pipes are a black-art form. Basically because not two pipes are equal. It is an exercise in compromise. One will work good in one area while fail horribly in another. "Back in the day", Honda would show up with a trailer full of pipes...Even today, the pipe from FMF or PC can be improved upon for you current riding needs, track condition, altitude, and barometric pressure.

However, there are pipes available for Can-Am's. Any that are made for the MX, work equally well on the TNT. The only real difference is the Rotery Valve.

« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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08 Speed Bird Quad 110, 08 KTM 144, 04 Suzuki LT-Z400, 03 Gas Gas EC, 300,97 Honda CR144, 96 Husky Boy 50, 88 Husky 400WR, 86 Honda CR125R, 80 Can-Am MX6 400, 75 Husky 360CR, 75 Husky 175CC, 73 Penton Jackpiner 175, 72 Husky 250CR, 72 Husky 125, 72 Rickman-Zundapp 125, (2) 71 Bultaco Pursang Mk

Offline SachsGS

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Tell me about 2 stroke pipes
« Reply #9 on: July 31, 2012, 04:00:29 PM »
Don't forget the ATK/Rotax pipes.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline VintageBlueSmoke

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Tell me about 2 stroke pipes
« Reply #10 on: July 31, 2012, 04:07:44 PM »
OK, I was wrong (yet again). The TNT and MX are different. The exhaust port size is different. Jemco and Circle F both have pipes. Don't just go with what is on their web site. They don't list everything.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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08 Speed Bird Quad 110, 08 KTM 144, 04 Suzuki LT-Z400, 03 Gas Gas EC, 300,97 Honda CR144, 96 Husky Boy 50, 88 Husky 400WR, 86 Honda CR125R, 80 Can-Am MX6 400, 75 Husky 360CR, 75 Husky 175CC, 73 Penton Jackpiner 175, 72 Husky 250CR, 72 Husky 125, 72 Rickman-Zundapp 125, (2) 71 Bultaco Pursang Mk

Offline 2T Institute

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Tell me about 2 stroke pipes
« Reply #11 on: July 31, 2012, 10:29:03 PM »
Quote from: VintageBlueSmoke on July 31, 2012, 08:04:08 PM
2-stroke pipes are a black-art form. Basically because not two pipes are equal. It is an exercise in compromise. One will work good in one area while fail horribly in another. "Back in the day", Honda would show up with a trailer full of pipes...Even today, the pipe from FMF or PC can be improved upon for you current riding needs, track condition, altitude, and barometric pressure.

However, there are pipes available for Can-Am's. Any that are made for the MX, work equally well on the TNT. The only real difference is the Rotery Valve.

It is far from a black art. What is not understood is that everything must work together.
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Offline SachsGS

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Tell me about 2 stroke pipes
« Reply #12 on: August 01, 2012, 12:24:55 AM »
Don't forget that the stroke changed over the years, MX2 57mm to MX4 61mm (I think).
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Tell me about 2 stroke pipes
« Reply #13 on: August 01, 2012, 12:36:07 AM »
Quote
Why would you want your bike to be loud, louder than a four stroke of all things. loud bikes are ruining our sport.
  It was a one time run with it in the woods (way out in the middle of no where where I live). It was just good fun and I wanted to see if I could make my bike louder, obviously I did, but I ran it once in the woods and hung it back up in the garage after I proved my point to my friend  ;D Trust me, I didn't like not hearing out of my right ear, but the only people I bothered were woodland hermits  :P
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Offline riffraff

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Tell me about 2 stroke pipes
« Reply #14 on: August 01, 2012, 06:12:42 AM »
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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aaahhhhh yes, I remember the good old days
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