hydroforming an expansion chamber? tzr 125

[Walloper]

[Timmeh]

Also the reason why 2T cans are made the way they are. The length and diameter of the 'stinger' is just as important as the rest of the zorst.

Try running a full-power stroker with an open can and you''ll notice a loss in power.

Engines with loop scavenging are more sensitive to changes in resonance, which explains why it affects some more than others.

Some early engines that have only basic ports use zorst systems that don't have an expansion chamber at all, and adding one results in little or no appreciable difference.

Now compare that will highly-strung engines like the 90's race reps where almost as much consideration went into the design of the exhaust system as did the entire engine.
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GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you

[jordey]

[jordey]

[Walloper]

[bladerunner]

Walloper. You have obviously never hydro formed a pipe! A hand pump and water will not and trust me on this is not dangerous. A tire holds air...a gas....an exploding drum is gas...a hand pump that does a few cc at a time does not have enough volume to be a problem. I've had plenty of welds spring a leak or the metal crease and fail....opening a bottle of coke is far more dramatic than this surprisingly. I work with 1800 ton hydraulic presses and 150 bhp industrial compressors and you won't find me messing about with them. jeez I even wear eye protection when using an air line....it comes down to as soon as you Lose pressure it just becomes a pipe full of water.and being a liquid it does not compress so it does not keep bursting out UNTILL it's reached ambient pressure. When was the last time you heard of a brake line on a car or bike exploding? And they run 4 or 5 times as much pressure as you need to hydro form a pipe.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[_Iain_]

Am interested to see a thread in show/tell when this actually gets going.

The software you were reffering to is a bit pricey however - i'd be settling for a plain copy of the OEM pipe. Then once that's made you've perfected the process & can make a few prototype test pipes based on the software calculations.
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Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[Walloper]

[bladerunner]

Walloper once again you miss the point!


You purge the air first...as stated above.... Which you seemed to know already!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Pete.]

IF you purge the air first then you will have very little stored-up energy, and with no air inside a teaspoon of water/oil will release all the pressure.

If you don't, you could be in for a lot of pain/surgery. It's very possible to hydraulically inject yourself with the tiniest amount of oil but not very likely. Much more likely if you've got a gas compressed in there.

I use a machine that runs at 1750bar hydraulic pressure and has to be man-handled constantly in rough conditions (demolition). It's so dangerous in terms of oil injection that the pressure pipe - even though it's only a finger thick and the flow is tiny - has a second, loose sheath over it to contain any released oil to stop injection injuries so yeah - it's definately a consideration if you don't fancy being an amputee.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Walloper]

[Walloper]

[jordey]

[Pete.]

It's not as dangerous as riding the damn thing.....
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[bladerunner]

Yeah I think we better just let Walloper rant to himself a bit longer...I love how some people who have never actually done it have such strong opinions on how they "think" it will be
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Walloper]

[stevo as b4]

Yes but there's a lot of people also on here who seem to be quoting certain aspects of how to design a 2stroke expansion chamber who have never designed or built one.

In this thread I'm more interested in the mechanical aspects of how to use fluid pressure to shape a metal envelope into some kind of cylindrical vessel.

I'm with Walloper etc, with the people that are saying hydraulic pressure can be dangerous. Anyone who has worked with diesel engine fuel systems would know about that.

[jordey]

okay so this is going fairly off topic and tbh i cant be arsed to reply to most of it.

back to the point, what would be the best way to go about this?

it would be fairly easy to get the dimensions off of the original exhaust for the cutout, but this kindof defeats the purpose. i was thinking of buying the program on the first page (its not very expensive at $17), use it to produce a paper mock up of the exhaust, then use this mockup to make a flat template, leaving extra either end for the valve/ so the welded end can be cut off. does this sound like a good/ bad idea?

[bladerunner]

If its a bit of learning and skill development ..and it's only my opinion..would start off by mocking up the pipe and rolling cones if you have access to or make your own sheet roller....that way you can get a working pipe and get the routing right etc..it also allows you to alter the pipe more easily as you can cut and shut the belly section a lot easier then. Once you've got a pipe your happy with then have a go at hydro forming the final design. Hydro forming from the start is giving you a huge learning curve due to the extra variation of parts stretching and creasing that you only really learn by doing. It will still sound like a single cylinder 2 stroke though whatever you do....and a fair bit more tinny due to the single skin construction. It is an interesting project if your into your own engine development and like I said the TZ designs work well on the tzr with a little modification.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Frost]

I'm sure software like solidworks does sheet metal modeling so that might be a place to start.
Otherwise i'd just prototype it using progressively better designs and thicker metal. Something coke can thick could be formed using a foot pump and i'm willing to bet the bike would run with it on if you wanted to test it on a dyno.

[cb1rocket]

You will need to dyno test it now and then to see where the power is going is being created etc and adjust your design accordingly
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Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852