Putting things in places they ought not to be (250R Hybrid Motor build)

[El Camexican]

Just bought one of these since they were on sale; http://www.harborfreight.com/12-inch...l#.Ux5FxIWQr08


Got a good excuse to start on the pipe now

The few times I’ve contemplated what would be involved in transplanting a two stroke engine into a frame it wasn’t meant for I’ve always assumed that the easiest way to fit a pipe would be to cut one meant for the cylinder into small sections with a band saw and weld it back into a configuration that fits the frame.

So rather than build a pipe from scratch would it not be easiest for you to get a stock pipe from that sled, cut it into short sections and then tack it back into something that suits your frame before welding it all up?

[Billy Golightly]

In theory, yes. In practice out of trying it in the past, not really. The hydroformed pipes are never actually round, they are more oval shaped, so when you section one and try and turn the piece 180 degrees to get your change in angle, you have these big gaps in your weld joint. Particularly in sheet metal, this is a pain in the ass. You can work and work to try and get it to match back up but it just turns into a cluster real fast basically. Slight changes are doable (I've put a bunch of Cr500 pipes on 250R frames with some adaptation), but big substantial cuts and changes...just not happening in my experience.

[Billy Golightly]

Been working on trying to get a pipe, and not really having too much success doing it from scratch so far, but not giving up. Here is my forming die I've been using to help even things back out after sectioning (It hasn't helped too much )



No pics of the pipe itself yet...its kinda gnarly looking at this point.

[trike savior]

first comment but been watching the build closely and loving all of it. what is that you are using for a tool there. Old missile, bomb nose? lol

[Billy Golightly]

Yup...found it in a ditch about 6 or 7 years ago and its been kicking around the shop since then, I figured this would be a good thing to use it for actually!

[Thorpe]

Billy-- what about creating a few forms (typically out of mdf, then being able to grind and shape accordingly) and creating the pipe half at a time and welding two seams...? I spent years beating metal in a hot rod shop, and made many complex curved panels this way... Just my $.02

Or there are some really cool, simple ways guys are hydro forming their pipes on YouTube... (Stupid episode of mythbusters made me look into it more)

[Billy Golightly]

What seems to be my biggest challenge is when I cut the sections out, and then rotate them, the seams do not line up because the blade flexes and doesn't make a perfectly straight cut. That, and a combination of the sectioned piece not being exactly round, so that when you rotate it, it is ovaled and oblonged from positions where it'll match up. I know I'm missing some major part of the process here and I just cannot seem to put my finger on it...

[Thorpe]

Are you cutting with a bandsaw, or abrasive wheel? Have you ever looked into body s and dolly's? A few different shaped dolly's and well placed taps with a body would help your transitions, and even help you tighten up some of the gaps in your metal fit... (Guessing your plan is to tig weld your pipe...) I wish you and I were closer so I could give you a hand with that pipe build... Loving your motor build!

[Dirtcrasher]

^ I think Billy needs a big 12-16" stationary disc sander wheel with a 32 grit wheel after a rough cut with a band saw or sawzall. For such thin material, 36 grit is probably too much, but 60 or 80 grit may work perfect. I love my 12" stick ons from McMaster/Carr.

I made my own 12" on a base with an adjustable plate on the Mill, I'll take a pic. I made the shaft fit a metric grizzly disc with a sharp hand file and a micrometer. The motor and aluminum was free and the cast then machined backing plate was 17$.

Lay a 1/8th wide SHARPIE black cut line and use the sander to grind down to the edge of the line, and I'm sure Billy measures very well.

I have a 12" disc sander and that was my Mill and Lathe for years until I got divorced and seem to have more money now being single

Regardless, that stationary sander works perfect if you have a line you traced or scribed to follow as you sand the material and either to the line or lose the line sanded off. A band saw cut has to be a horror show for thin sheet metal. No luck tig or mig welding big open gaps in thin material, and you can each define your "gap" differently then Billy, I or you perceive it to be......

[Billy Golightly]

Definitely cutting with band saw, very very fine tooth blade thats only like 1/4inch wide on my big 30in throat vertical I have in the back of the shop. I tried cutting a pipe with an abrasive wheel years ago and that was a nightmare. I've never used any body s or dollies...I'll look into it but I really wouldn't have a clue what I would be doing with any of it. I've been trying to use that rocket cone some but it just didn't seem to do what I needed it to do. This whole sheet metal thing is very much out of my element, I can weld it no problem but working and manipulating it is way outside my area of expertise.

I half wondered the other night if I needed to use a big disc or belt sander to sort of even them back out, but the problem is the tapers on some of these pieces are so aggressive, I mean, if you take .080 off the width on something, its gonna drop down inside the mating piece, its kinda crazy.


Not gonna give up on it though!

[Thorpe]

Billy-- here is a link to some basic techniques that will give you an idea of what I was talking about... Starting about page 6 or so... I think it would help you in you pipe building. I am willing to bet you already have a decent selection of s, and Often times the dolly is nothing more then a pipe, or odd piece of metal that fits the contour, no need to go out and spend a fortune on some sweet Martin body tools...

http://www.tachrev.com/JeffLilly/.pdf

[mart]

Great work billy
Easiest way I find to do pipes is download self a little program called cone layout.puch in the exact size if what ever size cone peice you want then prints out the layout for you. Cut the peices out of paper (number them as you go an actually build the pipe out of paper once happy undo all the paper templates then trace each one onto sheet metal cut them out. Get your self a vice mount set of hand rollers and roll each section up an then weld her up. Heaps of work yes but it's an easy way of doing it.

[atc300r]

Here a vid from youtube hope it helps.

[Billy Golightly]

Great work billy
Easiest way I find to do pipes is download self a little program called cone layout.puch in the exact size if what ever size cone peice you want then prints out the layout for you. Cut the peices out of paper (number them as you go an actually build the pipe out of paper once happy undo all the paper templates then trace each one onto sheet metal cut them out. Get your self a vice mount set of hand rollers and roll each section up an then weld her up. Heaps of work yes but it's an easy way of doing it.

Thanks Mart...thats pretty much what I was going to try and do next, I had been wondering how the heck people figured out the exhaust layouts for each individual section and the only way I could see doing it, was to build the pipe out of a cardboard/paper template and then break it all back down and cut each individual section to lay flat, so I was on the right track. I have the cardboard template rolled, so perhaps I'll take the time to do that this weekend as I really want to try and this part of the puzzle wrapped up. I appreciate you chiming in with that as it gives me some re-assurance I wasn't totally crazy

[WIkid500]

I agree with making the pipe in a straight section then cutting it to fit the frame. The best way to figure the cones is google up a cone layout excel file. They make it simple to make your end cone pieces. From there you use a slip roller and get busy making things round. Make sure to measure the saw kerf and guesstimate how many cuts you plan on making to section the pipe, add that to your overall length of the body. A band saw is the best to get a straight cut.

Awesome project, can't wait to see it fire.