BMW Bitsa build

TwinPlug

Cambridge, UK
Having read Buckeyebike's excellent thread, I thought I'd post my own BMW build up.

I originally started out the project going for a Cafe racer style build, but part way in to the build I noticed that I was going to be replacing a lot of parts I already had, I also stumbled on some pictures of an BMW R69 which changed things slightly.

I worked out what the differences would be and found that it mainly came down to just the seat and guards, along with some detailing, so I'm not building it up to resemble a slightly modded R69, if I decide I don't like it, I can change the guards and seat to go back with the Cafe style.



I bought some parts from a guy I know which was a BMW R100 but with no frame, fairing/plastics/lights/calipers and some poorly forks.

I then found an Ex-police R80 frame with V5 for £70, which went straight off to be 2 pack painted in gloss black.

I tried the engine and found it had a knocking big end, so hit eBay and got a known good bottom end, minus barrels/pistons/heads, again for £75

The wheels to the bike were cast alloy ones and I wanted normal spoked wheels as the cast wheels just don't look right on a Cafe Racer in my opinion, so started looking and found a complete front end with good forks, saveable callipers and spoked a spoked wheel with discs along with the matching rear wheel, so snapped them up - they're far from perfect, but I will be getting the wheels rebuilt with Morad Valanced rims and stainless spokes etc, so it's not really an issue.

I've basically been going through all the parts I'll be using and giving them a thorough cleanup and replacing seals and bearings where needed, I started with the bevel drive unit and despite all the BMW dudes saying "Buy a refurbed one, don't take it apart" I took it apart (making special tools where needed) and the bearings were fine thankfully, but replaced the seals and gave it a good clean & semi polish.

Next up was the front end, I stripped the forks down and gave them a good going over, powder coating the legs in gloss black and replacing the seals and giving them a general once over.

On a stock BMW the top yoke is a very functional, but awful looking sheet steel jobby that requires special attention when assembling, I thought 'Sod this' and set about converting the spare alloy bottom yoke into a top, which involved a large amount of filing, sanding and polishing with a dremel and a DA sander with fine pads, once I got it looking how I wanted it, I needed to remove the steering stem bolt and machine a recess in the yoke to accept the shiny new stainless centre nut

I've got a small lathe and a good selection of tools, but there was no way I could do what I wanted, I nearly gave in and took it to an engineering firm to have the work done when it dawned on me that my dad has a massive pillar drill, so I headed over to the parents house armed with some cutting tools and mounted the yoke in on the pillar drill, fitted a 13mm cutting tool and setup the job, to my amazement it did the job very well indeed and I managed to machine out a stepped recess that the new top nut sits in perfectly.

Thing were looking promising so I started thinking about the fork top nuts themselves, again, they are very functional, but look crap, BMW's answer is to pop plastic covers on, slightly less crap looking, but it's still plastic.
After some googling and consulting the Clymer manual, it seemed I may be in luck and able to use top nuts from a much earlier bike, so I asked on the airheads forum and found the /5 nuts fit straight into the later forks, so I ordered some second hand ones from a BMW specialist, along with the chromed screw on covers - they really look the part.

I took the Brembo callipers apart and ordered 2 seal kits, gave the calliper bodies a go in my bead blaster and then powder coated them gloss black, they really look the part now, one of them had a knackered thread where the bleed nipple goes, so I bought an M10 x 1 helicoil kit and repaired it in about 5 minutes, it seems to hold all the pressure I can give it with compressed air, so should be good.

Again, thinking about the controls and layout I started looking for alternative speedo setups, me being me, I really didn't want to go the 'off the shelf' look, so had a good rummage on eBay for some clocks.
I found some place selling off a brand new set of clocks for a BMW R1200 Custom style bike - a particular model we don't get in the UK, so researched the wiring and satisfied myself I could get most of it working on a normal bike and hit the buy it now button - £99 + post.

The clocks arrived and are gorgeous, they are housed in an alloy casing, painted silver, so I'll be stripping that crap off and will get them bare alloy with satin finish.

I worked out all the wiring on the bench with the exception of the speedo drive, I'd made a bit of a balls up - the R1200C is a modern bike and has ABS, the speedo is driven from the ABS ecu, my 30+ year old machine isn't going to have ABS.
Again, after nearly sending it off to have it altered to run from a cable, which would have cost a good few hundred quid, plus both the funky speedo and the old cable driven one I gave it one more last thought and remembered I've got some engine ECU trigger wheels and crank pickup sensors, so shot out to the shed armed with a trigger wheel/sensor/funky speedo and a 12 battery, chucked the trigger wheel in the lathe, clamped the Mondeo crank sensor in the cross slide, wired it up and got it to read.

With refreshed enthusiasm I went googling for info on ABS equipped BMW's, within 20 minutes I'd found that all I need is an ABS sensor ring with 100 teeth (most modern BMW's have these) and an ABS sensor and the speedo will work and be accurate - relieved isn't the word :)

The rest of the work so far has been stripping/cleaning/painting/reassembly - I've found it therapeutic and a great way to destress after working for a bunch of morons all week.

The rear shocks were a little rusty, mainly on the springs, they are Hagons and they aren't leaking and have good damping, so I clamped one in the vice and used a ratchet strap to compress the spring while I took the clip out of the top, they came apart very easily and set about cleaning them up, gave the bodies 3 coats of Simoniz Wheel silver (it makes a great etch primer) and then 3 coats of gloss black, followed by 3 coats of clear coat - they looked great until I tried to refit the adjust rings, which scratched the new paint - arrggggg - with the paint sorted I needed to open the adjuster rings up so they'd clear the extra paint, so chucked them in the lathe and got a little carried away, put it this way, they now shine beautifully and fit well.
The spring had a slight amount of rust all over them, it would come off with a sanding pad, so I started working on this and then discovered if I forced the whole pad into the spring I could pierce it with a screwdriver and wind it around the spring, the first spring took me a good 90 minutes to get good, the second one with the new technique took about 10 minutes.

I'm hunting down some stainless shrouds for the shocks to complete the 'jam pot' look.

Anyway, I've waffled enough, here's some pics - click on the pic itself to open a larger version, feel free to comment either way, but keep it civil if you can :)

first image is the inspiriation:

AEG.R69.jpg
























 
Cheers Buckeye,

After spotting another Airhead on here I've decided to pinch some ideas, namely the striping & silencers.

Buckeyebike's lovely build is here - http://www.dotheton.com/forum/index.php?topic=37222.0
 
Cheers chaps

Not much to report this week, I'd started fabbing a number plate/rear light/reflector mount up from some 4mm aluminium sheet and needed to radius some curves for the lamp and reflector mounts with my lathe.

I've not used the lathe for some time and it's chattering it's head off, so stripped the bed completely down and gave it a once over, got it all nice and it still chatters - I've since found the spindle bearings have got damp and corrosion set in of the races, so they need changing (and looking after better!!!) so had to rough it out and do the rest by hand.

All the lathe tinkering pretty much used up my weeks workshop time, so didn't make much progress at all....

The roughed out article:

 
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