Sunday, 27 June 2010
Sunday, 20 June 2010
Aside from the lack of paint, I think it bears more than a passing resemblance to a real one. That's not really a surprise as making motorcycle accessories of this type was my day job for a while, and I've had a bit of practice at it.
I've also made a start on the rear sets, and once again I'm making them rather than buying them. Not because any that I bought wouldn't fit my preconceptions, and not because something else I've done would stop off the shelf ones from fitting either. No, this time the reason is simply that I quite like buggering about on the lathe. The adjacent photograph is the sort of thing I've got in mind for the footrests, though I didn't want them to look quite that chunky, on the other hand, I don't want them collapsing in use. I also want to use something other than a bend at the end of the linkages to locate them, not only for the look of the thing, but to provide a little adjustment too.
Monday, 14 June 2010
Nothing overly dramatic I'm afraid, although, the tank did arrive. It turns out that an R80 has somewhat different fuel tank mounts than an R65, despite the frames appearing to be identical.
"Appearing to be identical" is deceptive though as the R80 front tank mount appears identical to the R65 one at first glance, but place the tank on the frame, and something is clearly amiss. The front mount consists of a "C" section channel bridging the tunnel of the tank, and a horizontal piece of tube welded to the frame down-tubes behind the headstock, with a rubber moulding that sits on the tube. The tube on the R65 frame is not only slightly longer, it's located lower too, and sitting your long awaited R80 tank onto the mounts reveals that there is no clearance between the starter motor and the fuel tank. Luckily I realised that the mounts were different before despondency set in.
I've got as far as making a new mount for the front of the tank, and I'm thinking of ordering the rubber cotton reels for the rear of it and making some suitable brackets to weld to the frame.
After a ridiculous amount of farting around, the motorcycle now has the makings of an exhaust. I say "an exhaust" as it may not be "the exhaust" since I'm not too sure about the way the pipes run under the engine. I feel they could do with following the line of the sump rather than floating around in mid air like that, which would pull them in a little closer at the front as well. Because the left side cylinder is further forward, the pipes converge to the right of the bikes centre line, making them near as damn it equal length and overall the effect isn't entirely unpleasant, and it seems that I'm the only person who isn't enamoured of it. I think I'm going to take one more stab at it as I have the tube to do that anyway, and the collector I made is a slip on one so that at least could be re-used.
I've also sawn the threaded stub off of the left hand cylinder head, which has left no means of securing the front pipes to the heads. I'm planning on removing the heads and drilling its fins to accept some springs which will hook onto the exhaust pipes, rather like you might see on a moto-cross machine. The pipes I've made are 1 1/2" OD, 1/16" wall, so and I've put short stubs of the 1 3/8" pipes that came on the motorcycle into the ends of those to locate in the exhaust ports.
The final thing I did was to make all the parts for a fork brace. I'd resolved to spend money more freely on this project as opposed to my usual "I can make that..." approach, and I knew you could buy fork braces not unlike this. However, I had been looking at what I had in the way of 7/8" tube formers, and looking at the one on a conduit bender I own, it looked to be about the right size to make the inverted "U" pieces. A test bend revealed that it was, in fact, exactly the right size when used with the tube I had lying around. Making the mounting brackets from some 1" x 1/4" steel strap was going to be easy enough so I made one and tacked it up. I don't really like the strap brackets, and am toying with the idea of jig sawing some from 1/4" plate, which would look better, and make the brace stiffer. It would also give me somewhere to drill some lightening holes, and I find the idea of adding some extra metal so I can drill lightening holes in it vaguely amusing.
The rear sub frame is causing me to lose some sleep. It's ugly, flimsy, and ridiculously heavy for the amount of stiffness it possesses. It wouldn't be beyond the wit of mortal man to make something stiffer and lighter from larger diameter tube and weld it in place, contributing to the overall stiffness of the frame, which is a department where it is sadly lacking. The other side of that coin is that part of what makes a BMW café racer a BMW café racer to me, is that skinny subframe stripped of the side panels and battery mount.
Different is not a synonym for "better", but that doesn't exclude the possibility.
Monday, 7 June 2010
I made a start on a fork brace by drilling a couple of plates to attach to the fork's mudguard mounts, and then bending some 7/8" OD 12 gauge tube into a "U" shape to join the two plates together. Which of course sounds very easy until you consider that the bent "U" shapes have to have the same inside dimensions (or at least very close to) as the outside measurement of the two plates they connect.
Since the 7/8" former on my "proper" tube bender has a hopelessly large radius for this job, I ended up using a Record conduit bender as I not only have one, but I have a 22mm former for it too. The former was slightly undersized, which normally entails "over bending" the tube and then pulling on the legs of the "U" to get them parallel again, but as luck would have it, the spring back in the tube itself took care of it for me. That's all on the bike and tacked up, but I'll need to drop the front wheel to fully weld it and take it off the bike for a final trim.
Then I'll make a front mudguard for it that will mount directly to the fork brace.
On the exhaust front, I was face with an either/or choice. Either I made the exhaust out of bent tube as I wanted to, or I had a Snake's Nest exhaust, as I wanted to. While i can make bends up to 180 degrees in the tube, the radius is just a little too large to allow me to bend up a Snake's Nest without cutting and welding the tubes I bend or buying in some mandrel bends.
So, I think for now, I'm going to make a relatively simple 2-1 for it as I don't relish the idea of sitting down for hours at a time welding bends together.
There's a rumour that the fuel tank might turn up tomorrow...