This is a discussion on Budget Parts-Bin Bultaco within the Project Builds forums, part of the Caferacer.net Forums category; Could you just cut the pieces off from the main frame and weld just a pair of new sections of tube in? You could lay ...
Could you just cut the pieces off from the main frame and weld just a pair of new sections of tube in? You could lay a nice fillet in around there and add a small Triangular web in if your unsure about it. Shame after making those insert pieces though, as they're neat.
Glad your plugging away at it
I finally found the set of non-leading-axle forks I was looking for. I was able to score a set of '82 GS750EZ forks off Ebay for $100 shipped. Comparing them to the GS650L forks, they have the same length from the tube caps to the front axle, and slip right into my triple clamps (important, because the steering stem has been machined to mate with the Bultaco frame). I think I should get a much more comfortable trail figure now. I will need to pick up a couple of axle spacers to match, but the 750 and 650 take the same axle, so I will be able to source them from Suzuki's parts bin; nothing custom should be needed. I should also be able to make use of the GS750's integral fork brace.
Last edited by Tanshanomi; 08-09-2016 at 10:17 PM.
I posted this picture on a thread about the $120 tubing bender I bought, but I figured I should update this thread, too, since it is being used to fabricate the frame tubes for Bultakenstein. After testing out the bender with some hardware store conduit, I bought a couple of 4-foot lengths of 3/4" dia. .065 wall 1026 mild steel DOM tubing through Ebay. The bender did a fantastic job. I got a perfect, kink-free 180-degree bend with minimal time and effort.
However, if you look closely at how it sits on the diagonal frame extensions I machined previously, the loop is about half an inch too narrow. I might fudge it by spreading the loop a bit, or I might do something more precise to make them line up. I still have to bend the front of the loop in 30 degrees on each side and marry them to the existing seat tubes with an internal plug, similar to the way I mated the rear supports to the frame below. I am thinking it will be easier to bend the front tubes separately and then weld them to the loop, rather than bet that i can make three bends all perfectly in plane, then assemble with internal plugs there as well.
No time to make a nice, neat diagram, but this is quickly scratch-pad thumbnail sketch shows what the idea is.
...unless anybody else can suggest a better approach.
I also haven't come up with a way to positively attach the diagonal supports to the loop beyond just gobbing them together with a weld. I have been striving to always build in a more secure, mechanical secondary means of attachment.
When I started this whole deal, my stated purpose was not to come up with a fantastic motorcycle, but to gain knowledge of the whole customization process. And at this point, one conclusion has become vividly apparent: motorcycle customization, at it's simplest and most effective, is framebuilding. Think about it; ou can spend years learning how to hand-form a fuel tank with a shot bag and hammer, buy a Bridgeport and mill your own triple clamps, fabricate an airbox out of carbon fiber, all to fit the original chassis. But there are countless component parts already out there. The perfect wheels, seat, engine, etc., are probably already available; they just need the proper framework to fit together. If you can bend tubing accurately, cut and drill plate, and weld it all together properly, you can make just about any configuration of parts work together. And so much of the bodgery I see is from people trying to re-form and re-constitute a motorcycle, while under it all reamins a frame that's ill-suited to what they're trying to accomplish.
Okay, before I get flamed—yes, that's a gross oversimplification. It only applies kind of very conventional (some might even say outdated) designs my tastes run toward. The state of the art today is pressure-cast aluminum alloy spar frames, not steel tubing. It takes a whole factory building full of expensive machinery to create the super light, super rigid track bikes used in modern competition, from trials to MX to road racing. And even if you're creating a more modest street bike with a tubular frame, not every component is going to work together without modification. For example, many fuel-injected bikes have specialized fuel pumps built into the tank; trying to use another made and model tank is going to be problematic, even if the frame accommodates them both.
But I think my point still stands: even if you have a lifetime to become a master in every aspect of fabrication, the one skill that an individual can acquire that makes the widest array of custom fabrication options practical is being able to conceive, lay out, and build a good frame from scratch.
Last edited by Tanshanomi; 11-16-2016 at 08:44 AM.
Oh thats like a low hanging apple there. Somebody take a bite....
Project looks really cool, i better read it tonight before i weigh in.
I carry a gun because I'm too young to die, too old to take an ass whooping, and a cop is too heavy.