Something about the work I did and things I learned

Over the months I got my hands dirty many times doing various servicing and renovation jobs and though I won't claim to be an expert on any of it I now have an opinion about what much of it involves and what can go wrong!

As I got to grips with the bike I picked up lots of info (actually the vast majority of it) from various Internet sources. The best of these are the Airheads Beemer Club technical articles and the Boxerworks and Motobins forums. One thing I learned is that there is a lot of folklore and opinion around older boxers, the net result being that you need to read up, try things out and draw your own conclusions. A bit like child rearing really.

I also tried a few different mods / upgrades to the bike with mixed success. There are things about the R100RS that are less than perfect but there is also something about it that makes it a single whole that is difficult (reluctant?) to improve on. Nonetheless I made small changes and gradually the bike developed a persona that reflected what I wanted out of it.

Handlebars

When I first got the bike I was really keen to change the handlebars and screen to give a more upright position and greater wind / weather protection. Early on I found that riding for any length of time with the standard handlebars caused severe pain in the back of my hands, wrists and shoulders -which seems to be a fairly common complaint among RS owners.

I found a couple of examples of owners who had successfully fitted RT bars. Using the expensive method I found out that it isn't possible to do this on later models of RS that have the front brake master cylinder on the bars -the fluid reservoir fouls the fairing. The best I could come up with was K100 bars. These are about the same width as the RS bars but have a rise of about 5cm and with some fiddling can be made to fit. They didn't make much difference to the riding position -and if anything the pain in my hands and wrists got worse, so I went back to the standard bars.

So, guess what -over several thousand miles after reverting to the standard bars the pain gradually ceased. (I have to admit that with the rubber buffer removed I turned the bars up a bit as can be seen in the pic below.) I was regularly riding the bike on trips of 200-300 miles and most of the time I'd find it comfortable. Over time I adapted to the bike, developing muscles and riding techniques to compensate.

Bottom line -I persevered and after a while the bike broke me in.

Wider mirrors

This is a simple story of relative success. The standard boxer mirrors are nice and neat to look at but unfortunately are small, vibrate a lot and are so close together that unless you're the width of a pencil then all you can see in them is your arms. The obvious solution was to fit a set of replacements on longer stalks. Inspired by the success of others I investigated various spares catalogues and dealers. In the end I found a nice set of cheapo ZX pattern mirrors at Thunder Road motorcycles. The fixing holes were wider than the originals so an extra set of holes had to be drilled in the fairing to take the forward bolts. The rear fixings went through the same mounting as the originals, which attaches to the metal fairing mounts. I used a strip of aluminium as a very large washer behind the forward bolts, which are only seated in the fibreglass of the fairing.

The materials used in the mirrors weren't BMW quality and they still vibrated but they gave a much better impression of what was going on behind. For around £25 I'd recommend this as a worthwhile addition to any R100RS.

Indicator repeaters

This was a straightforward addition to counter the effects of ageing on my short term memory. I found I was forgetting to cancel the turn indicators after going round corners. The standard indicator light between the speedo and tach wasn't bright enough to grab my attention in daylight so I had to do something to uprate it and avoid looking stupid and upsetting other drivers / riders.

I've been a fan of LEDs for some time and this was a chance to install a couple (the world needs more LEDs). I used two ultrabright panel mount green LEDs with internal resistors from RS Components. These were easily mounted by drilling a hole on the dash either side of the voltmeter and clock (for left and right). I wired them straight into the front indicators using piggyback spade connectors.

The LEDs were really bright. They were clearly visible in bright sunlight and because of their positioning they reflected off the inside of the screen -it was hard to ignore them. At night everything within a several metre radius was intermittently bathed in a green glow.

Handling

Having been away from riding a bike for many years I'd really lost a lot of feel for what constitutes good or bad handling. From what I'd read I expected the R100RS to have some handling idiosyncrasies -heavy steering due to the narrow bars, tendency to waver at speed, tendency to stand up or lie down in bends due to torque reactions, and so on *. For the first few weeks I found it a real handful to ride. The handling was soggy and bouncy -tired springs and not a lot of damping. The main source of problems was the front end but the rear shocks were also well past their sell by date. It also soon dawned on me that the steering head bearings were past their best and had a nice notch in the straight ahead position. The bike also tramlined badly, and an alarming front wheel wobble could be caused by going "hands-off" while slowing on a slight curve at about 35mph. Possibly down to tyre choice but no doubt aided by the list of other problems.

The first step was a fork strip-down and rebuild. Like most other work on the bike this turned out to be a relatively easy job and, while it took me a couple of weeks to complete, with proper preparation it could easily be done in a day. The best guide to rebuilding forks of this era is by Randy Glass -certainly a great deal more information here than is provided by Haynes.

The rebuild involved replacement of the fork oil seals, damper pistons, springs, oil and fork gaiters. Standard springs were replaced with progressively wound alternatives from Progressive Suspension; standard 5W fork oil was replaced with 10W.

Removal of the steering head bearings has been discussed at length on the Motobins forum and there's a good technical article on the Airheads site. The top bearing and race were easy to remove but the bottom set is much harder -the bearing cage is a tight fit on the lower fork yoke and the race is tucked away in the frame with nothing to hook a puller onto nor easy access for a drift. In my case it took an afternoon of careful work with a Dremel to cut and grind away at both parts. The most efficient way to remove the bottom race appears to be to weld a couple of blobs of metal on to give purchase for a drift to be used. Installing the new bearings is easy but care needs to be taken not to mark the faces of the races as you knock them in.

I was also unimpressed by the standard fork brace and top yoke, both of which are fairly lightweight pieces of pressed steel. The top yoke seemed particularly poor, having no way to clamp to the fork stanchions but relying instead on extremely tight stanchion cap nuts nuts to clamp the plate on top. I managed to source a second hand San Jose brace and billet aluminium top yoke (with proper clamps) from Motorworks. The brace was fairly rusty so I had it powder coated in black; the fork lower legs were done in silver at the same time.

When I put everything back together there was an all-round improvement in the feel of the front end. Much less dive when braking and generally more positive, especially in the twisties.

* By the way I didn't find the steering heavy once moving faster than walking pace, the bike didn't wobble at speeds up to 100mph (I didn't bother trying to go faster) and as far as I'm concerned the oft-mentioned torque reaction is barely perceptible.

Synchronising carbs

The quality of the carb setup has a marked effect on how smoothly 1000cc BMW engines run; careful balancing of the throttle openings (using the cables) and mixture (pilot screw and float level) makes a huge difference to the smoothness and feel of the bike. Actually it's been great to find out that the bike will run with the carbs way out of line but unless you like it shaking like a wet dog at low revs then you really need to get intimate with them.

When I first tried to synchronise the 40mm Bing CV carbs I couldn't get hold of any vacuum gauges. Instead I decided to try out Robert Fleischer (Snowbum)'s "low cost" carb balancing method -it's a great article and I must say I was pretty impressed with the results. This method can certainly get the bike running very smoothly at tickover, pulling away very smoothly and feeling at ease at higher revs. I did learn a few things to watch out for when using the "low cost" method...

• Spend time making good plug shorting devices -they need to be fairly robust.
• Allow time and don't rush when doing the balancing. First time took me a good two hours end to end -much less since.
• This is an iterative process. Expect to go round the loop a number of times.
• Make sure you only run the bike for a few minutes at a time. If you don't have a big fan to cool the engine then get a stop watch -it's really easy to get absorbed and lose track of the time passing! I set the timer on my wristwatch to beep every 6 minutes and switched off for 3 or 4 mins. The switch-off time gave me a chance to think about what I was doing and allowed me to complete the work without even blueing the pipes.
• If you've been doing other work that that involved setting the timing then be prepared to recheck and reset. I had initially set it using the strobe with the engine running pretty roughly -as the running settled down I was able to improve the accuracy significantly.
• If you're using a screwdriver to do the shorting then wrap some insulating tape around the top few inches of the blade... it's remarkably easy to let a stray finger come in contact with live metal -big ouch.

Though I felt good about the results achieved using this approach I still wanted to try out vacuum gauges. This would allow me to see how close I actually got to getting the carbs in balance, to see if I could make it run better and because popular opinion seemed to say that vacuum gauges are best.

Still reluctant to spend any money I made up one of the low-cost plastic tube gauges. I think it has great potential to give accurate results because of the length of the column of fluid you can use. I found two main problems i) The fluid bouncing up and down in the columns with the alternating vacuum can make it hard to get a good reading. I damped the movement by fitting a couple of restrictors (smaller tube) in the pipe. ii) if the balance is significantly off then the fluid can get sucked right out on one side, requiring a quick disconnect from the carb followed by a wait while the fluid drains back into the "U". Again restrictors reduced this effect but didn't completely overcome it.

In the end I dug in my pocket and went for a Carbtune 2. I've used it on both the R100 and the R1100 and achieved good results. Though I actually get a smoother tickover on both bikes finishing off by ear. One thing I really like about the Carbtune is the fact fact that I can ride the bike with it taped up to the back of the tank to check how the balance looks when on the move i.e. in real conditions rather than sat on the driveway.

Boyer Bransden ignition

Tyres

Continentals are ok but do tend to tramline. Avon Roadrunners are much better!

The big stripdown

In Nov 2002 with 63500-odd miles recorded it was time to open up the engine. I originally planned to do a top end only overhaul -the bike was giving out some blue smoke and I wanted to have it converted to unleaded anyway. Well one thing led to another and as well as doing the valves and valve guides I also renewed the big end shells, small end bushes, pistons and rings, pushrod tubes and seals. Whilst many of the reciprocating parts were showing signs of wear the nicasil coated barrels were perfect -original honing marks still visible. As the bike was apart I also decided to go the whole hog and get the gearbox overhauled and the frame powder coated.

The engine and gearbox work was done by Cray Engineering in Sittingbourne. Probably not the cheapest option but the service was great. Jim Cray knows a thing or two about Boxers, takes pride in his work and is very helpful -5 star rating. The powder coating was done by Griffs Motorcycle Services in Bristol -Griff's a lovely bloke, the results are always excellent and the price is good but be prepared to chase him to get the work completed.

The main thing I learned through the whole process is that you really can take an older boxer completely to bits and rebuild it with basic tools and a Haynes manual.

The bike was back on the road mid-February, with no blue smoke and quieter -well, OK it still rattled like buggery but at least they were orderly rattles and I could explain all of them. Jim Cray's advice on running in was to take it easy for a couple of hundred miles then gradually open it up for short periods. I followed the advice and everything worked fine. One of the most noticeable differences was a drop in oil consumption -down from about a litre per 1000 miles to almost nothing.

The bike ran beautifully (-and I mean not a not a hiccup or hesitation) over the following 3000 miles until I sold it.