Sunday, 27 June 2010

I did say I'd try and get something finished didn't I? Well there you have it, one finished set of headlight mountings, and bolt on ones to boot. Though, I did bolt them on, decide that the headlight stuck out too far and that the actual bit the headlight bolted to had all the elegance of a duck in a ballgown, and set out to make some more.

So, despite getting something done, I still didn't manage to make it much of a "bolt-on" operation. To be honest, while I'm claiming that its done, I may visit the new brackets with a selection of drill bits and add a few lightening holes, because the new brackets, while made out of aluminium, are a little on the portly side at a quarter of an inch thick.

The quarter inch ally was the thinnest suitably sized piece I had floating around the place and I'd already been assaulting it with my trusty Bosch jig saw to make the rear sets to the motorcycle.

I machined the footpegs from some 1 3/8" aluminium bar off cuts that I have (courtesy of my younger brother), and I hole sawed out an inner "washer" out of some 3/8" thick aluminium that came out of the scrap bin at Wasp Motorcycles ten or twelve years ago. The footpeg and the washer sandwich a piece of 20mm steel bar which has a 10mm hole drilled through it, and forms the pivot. I made the levers from the afore mentioned quarter inch ally plate, jigsawing them out roughly to shape and then finishing them with a selection of files. The levers are composed of two parts, the obviously lever shaped bit, and a teardrop shaped piece that lives behind it and will connect to the operating rod eventually. The lever has a selection of holes drilled in it and the "teardrop" has two threaded holes in it, which makes the whole set up widely adjustable.

I used the original gear lever to get the dimensions for the ones I made, which ought to mean the gear change feels very much like the standard one to use, as the lever ratios will be identical. The brake pedal is a bit more of a problem as my new lever has a 3:1 ratio and the factory brake pedal has something more like 6:1. That means that if I just hooked the new lever to the back brake, it would take twice the pedal effort to achieve the same amount of braking as the standard set up. It would also mean that the swing arm pivot and the brake rod pivot were nowhere near each other and introduce some interesting conflicting arcs.

To get round that, I'll make an "idler" lever that mounts in the same place as the factory brake lever, and has a 2:1 ratio, which will reduce the pedal effort and put the rod that actually operates the brake back in its original position, reducing the conflicting arc troubles to a minimum. I need, or at least want, to get some stainless Rose joints (Heim joints in the USA) to make the linkages. My dilemma there is whether to spend some extra money and buy a left hand tap and/or die so I can adjust the linkages without removing them.

The Tap and Die Co. in London has left hand 6mm x 1.0mm taps for £10 each, and the dies for £20 each, which is tempting, and once I'd bought them, I'll doubtless use them again.

Making the rear sets did consume most of the week, but in fairness to me, everyone who's looked at the polished items in the flesh has assumed that I bought them.

The other thing I made a start on was a front mudguard. In a spirit of scientific enquiry, I cut out a flat blank and fold the edge over while it was flat to see if I could make a mudguard by just stretching the middle without shrinking the edges.

"Yes I can" was the result of the experiment, but getting it to fit the BMW's 18" front wheel wasn't happening, although it was an admirable fit on my 21" Harley Davidson wheel.

Having found that particular orphan child a home, I went back to making one the usual way and shrinking the edges as well as stretching the middle. You can see the edge of the blank starting to ruffle up as I make the second pass along it with the arbor press. I made the nylon tooling and I have four different ones with varying amounts of "crown" on them, and I use them in the press to either force the metal into a hole in a piece of MDF to make a dent and stretch the material, or I use them on a flat piece of 1/4" steel plate to shrink the ruffles around the edge, or planish out the dents.

What I'm trying to end up with is a mudguard that has a cross section to match the "hoops" of the fork brace and a radius that closely matches that of the tyre once it's been fitted to the fork brace.

I find myself unexpectedly busy next week, so I may not have time to make a lot of progress. Though, the carburettors still need some cleaning, and soda blasting is something that needs looking into I think...

Sunday, 20 June 2010

I mentioned something about making a more elaborate bracket for the fork brace I'd made in the previous post. In theory, I should have been a bit too busy to manage that, but I managed to combine what I was busy with and making the brackets for the fork brace under the same umbrella.

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.

By now, my original idea of unbolting some stuff, bolting some other stuff on, and having a Café Racer, has mutated somewhat. While the fork brace does indeed bolt on, the original idea would perhaps have been more accurately expressed as "buying some other stuff and bolting it on". In a completely predictable turn of events, that has become "making some other stuff and bolting it on".

I always planned to make the exhaust myself, and while the "nest of snakes" idea wasn't viable with the radius of bends that I can make in 1 1/2" tube, I wasn't so wedded to the idea that I was prepared to sit down and make one by welding mandrel bends together. By the time I'd repositioned the engine (...bolt some stuff on. Ha!) and broken off the threaded exhaust collar on one of the heads, there wasn't a lot of option other than to make one anyway.

Now that I've made a tail pipe and a silencer for the system, I'm reasonably happy with the way it looks, so it's staying for now. I made the silencer from some 3" tube and some hand rolled cones. It has a perforated tube running thought it and that in turn has a washer welded in it's bore which causes some of the gas to be diverted through the perforated tube into the body of the silencer and then back into the tube after the washer. I've made some similar ones in the past and they seem to offer a reasonable compromise between offensively loud, and stupidly quiet, and given that you don't need to burn that much fuel (and hence make that much exhaust gas) to produce the heady 40 whatever HP the R65 manages, I imagine it will work satisfactorily.

I got some exhaust springs from Meredith Motocross so I just need to weld some small wire hoops to the front pipes and drill the fins for those. I'm thinking about seeing if I can get the exhaust aluminium metal sprayed before I paint it black, since it seems to me that heat proof paint sticks better to aluminium than it does to steel.

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.

Strangely, I began this post with the feeling that I'd made quite a lot of progress, it certainly felt like quite a lot of work, but weighing it up now, it doesn't look like very much headway. I think that's because I can't point at anything on the motorcycle (with the exception of the engine mounts) and say "That's finished". The exhaust needs the spring loops fitting, I've got one, potential, footrest for the rear sets, the tank needs mounts making for it, the fork brace need brackets for the, as yet non existant, front mudguard and the subframe (which has been granted a reprieve) still needs some work. I'll make an effort to get something finished and see how I feel about the amount of progress then.

Monday, 14 June 2010

Despite having assorted other things to attend to, I did actually manage to make a degree of progress with the BMW this week. As well as sorting out something on the GS 550 and more things of a one step forwards, two steps back nature on the Alfa trike.

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 did get a small amount done this week, but one of the things that slipped through the net was buying some more batteries for my camera, so, no piccies I'm afraid.

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...