Two Stroke Expansion Chambers

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Hi, this is my first post here and I wanted to share some pipes I welded for my 1972 Kawasaki H1 project. Material is 20 gauge mild steel, I did not have the resources to back purge unfortunately. Each pipe is made up of about fifteen pieces and it took days of welding.   After welding all the seams I tacked each pipe together for fit up.  This took a great deal of patience haha. The way they tuck should increase corner clearance greatly, and the tapered headpipe should add some serious performance. What do you guys think?
Reply:Nothing makes you understand why custom hand built expansion chambers are expensive like building them yourself. Huge amounts of time needed... (My own oxyacetylene welded 0,7mm mild steel attempt hasn't gotten further than in this pic, it is still uncertain what frame the engine will be mounted on so I'm stuck unable to test fit anything. http://image76.webshots.com/176/1/81...1vkGEsG_fs.jpg)What calculations or program have you used to design the pipes? Would be interesting to see some numbers about the cylinder ports and what rpm the exhausts are tuned at.
Reply:WTF pipes were designed by two guys in canada and sold as an unwelded rolled cone set. One guy is a welder tuner, the other has a background in solidworks both avid kawasaki enthusiast.  Two stroke expansion chamber design is better left to the experts.. I just weld. But yes I too would be curious to see some dyno results.
Reply:Somewhere I have pictures I found of someone who made some megaphones the way they supposedly used to make the ones on the MV Agusta GP bikes back in the day.  They cut out two identical pieces of flat sheet to shape and welded it together at the seems and included a bung on the end where a Schrader valve could screw.  After that a bike pump was filled with water and they pumped it up, then filed the seems smooth.  It looked great though I don't know how one would easily put compound bends in one without some kind of additional tooling, cerrobend, sand, etc...Those old big two strokes sound incredible, I remember being at a rally where there were a bunch of the Kawasaki triples.  Looking forward to seeing the finished product.
Reply:here's what a quick google search came up with:http://www.two-stroke-addicts.freese.../hydropipe.htmThe one I recall looked like it was being done in someones backyard.  Which always looks more dramatic!
Reply:Got the flanges licked.   Then more welding and bracket fabrication. They have to be rubber mounted or they will just break so I found some sweet bushings at the junkyard that worked perfect.   Outer pipes will get mounted next..
Reply:I should know how this is done... or maybe i shouldnt... But how the hell do you get in between the runners (where the duct tape is) to weld it?! Im a couple of beers in for the night, so that may be why its not coming to me, but how!? please! Nice work too
Reply:It is not a single manifold, there are three separate pipes. One by one they will be easy (oh well) to weld.
Reply:Now for the right pipe mount, I wanted it to look similar to the center pipe so.. here it is    Might as well build the left too    So the mounts are tacked and will get fully welded when it all comes apart again  cheers
Reply:2 Stroke Tuners Handbook by Gordon Jennings is an excelent book I believe all you guys would love. It has all the info you need for manufacturing expansion chambers for 2 stroke motors, along with motor building.The book is a bit dated but the material is still current for 2 stroke motor building. Jennings book uses motorcycles as it's subject but I have used it's info for 2 stroke snowmobile motors myself.You can also buy software for building your own expansion chambers that will do all the math (trig) for you.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Nice work !! I'm impressed with the determination it took to do this.... I love the old triples !!
Reply:Okay so I have been too busy to post updates, but the pipes are done. And loud as all hell! Im planning to leave them raw and coat the liberally with mop n glow. I now have a new understanding as to what it takes to produce theses things. But hey saved around $600 by building pipes myself. Silencers will come next, just gonna kinda test the water with Boise police first, Cheers Skeet     Last pic is of a current set of pipes a friend and I are building for his RD400 project. This town will be crawling with vintage superbikes haha
Reply:Looks good but you forgot the turbo Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by GambleLooks good but you forgot the turbo
Reply:Mick, by hinge I assume you mean the whole frame haha. I actually did quite a bit of frame bracing, but the spindly swingarm will however flex. I rebuilt the front wheel with an 18" rim and put 15" rear shocks so it will hopefully give it the handling characteristics and the 400. Plus the suspension will be top notch. I picked up a kh500 that I will most likely monoshock so that will be cool. Headtube Gusset
Reply:You don't see very many of those old two strokers anymore. They were prone to seize or they ended up with scored cylinders. When I was a kid, one of my dads friends had a Suzuki 250 twin.The oil line for the oil injection got a piece of dirt in it and the engine blew a cylinder on a long trip. The bike had to be trailered back home. After that he went out and bought a Honda 750 four stroke. I think your pipes look great, I wish I could hear it run.
Reply:you should try to  make it as a flat piece have only 1 or 2 seems and cap the end and on the other end have a flange plate with a hydraulic fitting and blow it up like a balloon also hydro forming if i remember correctlyLincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:Those babies are sexy! Excellent workmanship!
Reply:Originally Posted by Mick120Reminds me of when I raced sidecars in NZ back in the 70's.A mate of mine and I built the outfit, powered by a worked Suzuki 750 triple. (Water bottle).