imago

This is a key, and really important point for me. No one knows everything, no one has the theory on everything, but the information is available and all you have to do is take a few minutes to find it, read it, and then apply it to whatever you're doing.

Quite honestly there's no way I could justify, let alone afford building the engine that's in this now. I totted up a rough cost and to get an engine to this state would be eye watering. Fortunately as I had most of it here gathered over the years I could put it all into one without costing anywhere near that, and have a good use for it. The engine is :- Spot on cases with all threads in tact, stripped, vapour blasted and Cerakoated. Crank stripped, built, and welded by Roger Upperton from a total of four cranks to cherry pick the best bits. Barrels bored out to take pistons. Pistons from a one off batch made specifically for endurance race engines (light, raised comp, minimal skirts etc) New Ape cam chain. Head stripped, flowed, ported and larger (EF) valves fitted again by Roger Upperton. Stage 2 cams. etc, etc, the list goes on. If you wanted to start from nothing and buy all the parts along with the labour you'd be well North of £6k. A well built turbo charged oil cooled engine with a turbo kicking out 250 - 300 hp would cost about half that. That said, the end product will be a completely fresh build of a rare bike, and it's very unlikely anyone would be daft enough to chuck that sort of money into building one like it.

I reckon it'll be nearer 200 personally as there's quite a few bits to go on yet, but it'll be interesting to see. One other interesting thing of note were the rims when they had tyres on. The sidewall structure and air pressure within make them way more rigid than without. It's removed all the flex from them. Presumably it's the same sort of effect as a bonded windscreen in a modern car/van in that the tyre itself has become a stress member for the wheel. I went with Bridgestone S23 in the end BTW.

That and the tube wall thickness are the key issues. The shock mount becomes a lever and the tube the pivot. As I mentioned before, think of stilsons on the tube, or a spanner on a bolt and it's easy to see how much force is being applied. That force is in a direction that nothing involved is designed or spec'd for, and also bear in mind that the tube which was under spec when new is now over 40 years old. It's a shit idea, based on piss all in the way of engineering knowledge or even basic physics. However, as always people are free to do as they chose and ignore what they don't like. It always makes me chuckle when you get the "I've done this that or the other for years and it was fine." comments. You get it on every subject from wiring, through engineering to structural design. There's no point in arguing with it as if they didn't get it the first time round they won't any subsequent times either. The information is widely available, and these days you can even get engineering calcs done by simply inputting numbers. Still, the ubiquitous 'Bloke on the internet' will have his say and it's much quicker than actually finding the relevant information.

I remember you saying that, and also the similar weight for scratcher. Once I'd got my head round what sort of bike/project it was then the aim was to build something similarly light and nimble. Then I decided to start using the goodies store and get as much out of a normally aspirated air cooled engine as I could to replicate a race bike's weight and performance from back in the day. The K1 GSXR makes an excellent template at 200 Kgs and 160 hp give or take a touch. Hopefully with either injection or smooth bores (TBD), a big valve ported head, taking the displacement out to 1168, lightweight pistons taking the compression up a touch, stage 2 cams and a free flowing Cowley exhaust it should achieve that but not be right on the edge so be reliable. The overall package being a creation from a long gone era that will keep up with, if not actually embarrass, much more modern machinery, that looks the nuts. Going the stage further and fitting a turbo'd oil boiler would take it away from the '80s race bike thing.

OK, I've got it down to two possible colour schemes for the Dresda. Either a variation on Martini racing, white with a single orange stripe bordered by blue off centre on the top surface of the tank and tail. Or, the VW Harlequin multi-colour as squares on the tank and seat/tail. Thoughts?

Back into some of the little jobs, first up the sprocket carrier. Original bearing size was 17 x 47 x 12. Changing the spindle from 17 to 20 meant a new bearing was required, but 20 x 47 x 12 isn't available as a sealed bearing. The easiest option then was to open up the bearing housing by 5 mm and use a 20 x 52 x 12. When the bearing arrives I can then build it up, make the wheel spacers and get the rear wheel set. Once that's done I can check the chain run and see if I need an offset sprocket, then get the chain and sprockets ordered.

How it started, how it's going. It's exactly three months since I picked up the Dresda frame. Making real progress now. Well on target for the weight too, it's a shave under 125 Kgs as it sits.

I can't remember who made them, It was either someone on OSS, or someone on FaceBook. That's not much help I know. I'm sure @davecaraor @clivegtowill know.

It's a combination of what they're in, and the angle the shocks are meeting it at. If you imagine putting a pair of stilsons on the frame tube at that point and giving them a good heave that's the pressure and direction of torque each time the suspension is compressed. Barley sugar anyone? The original position had a gusset fitted to take up the additional pressure and the force isn't at 90 degrees to the tube.

For starters I wouldn't fancy it straight through the frame tubes like that, too much leverage on the stubs. You can get inserts to replace the originals, and in the original position they're as good as you'll get. Basically they're just a stepped solid bar for each side which you weld in. The shock eye slips over the smaller dia on the stub and there's a threaded hole which you put a bolt into.

Bloody certain, I don't want even more expense!

I'm going to stick all of the electrical stuff under the seat/tail unit on a tray. There's not going to be loads as I want to keep it pretty basic, switchable fuse panel, ECU for the injection, starter relay (may go by the engine TBD) reg/rec and the battery. That'll leave things clear up front for a small GPS speedo a rev counter and minimal idiot lights. I think it'll look better with as much free space as possible up front. At the moment (again TBD) I'm thinking a single large round headlamp. Tthat may change as I have a couple of other possibilities in mind, but it won't be having twins on it.

I'm sure I'll regret it when the aches and pains set in, but those adjustable clip ons are staying. They're a really nice bit of kit and suit the bike.

Time to have a look at the electrical tray and battery mounting. Tucked into the seat unit seems the logical spot.

I just measured width, depth and height, never gave a thought to the frame taper and the width at the carb tops. That'll teach me, but it's all part of the experience. I'm warming to the injection idea now, and I have most of the stuff I need anyway so it'll be a shit load cheaper to convert it to injection than to buy another set of carbs, jets and dyno time.

Yeah, straight into the boots with no wrestling or twisting.

Part of the reason I chose that colour for the frame was the ceramic coating on the exhaust and the Cerakote on the engine cases.

It's just the right build to use up a bunch of stuff that I've had for ages waiting for the right project to put it on. Then you realise unless you get your finger out and actually use it someone will chuck it all in a skip before your ashes have cooled.

As a moral boost and to make sure I don't run into alignment issues there trial fit of the Cowley exhaust.

Yeah it was at GT750 triple originally, and whatever happens I won't be putting one of those awful creations back into it.

Following the long standing OSS tradition of 'in for a penny' there's a fuel injected air cooled engine coming to a Dresda frame near you.

CV's are worse (I have a few sets here) as they're wider at the diaphragm housing. I suspect the GS1000 had smooth bores which are much narrower at the top. The original triple would have been fine. Throttle bodies will fit, but I didn't want to go the injection route with this one. Injection, find smaller carbs, manifolds with twin carbs, or change the engine for something else seem to be the only options. None are particularly attractive at the moment, but a bit of thinking space will put things into perspective.

"My path is strewn with cow pats from the devil's own satanic herd." Bollocks. There may be a solution, but still, bollocks. I really don't need or want the complication of an injection conversion.

It'll be fine as it's snug between the sides rather than at the front. Glad I didn't put the head on first though as there'd have been some bad swears when it became apparent that it wouldn't fit between the rails and had to come off again.