Why buy a newer Boxer?

Some people would say 8-10 year old bikes don't qualify for the title "newer"... it depends if you're comparing them to a 20 year old bike .

From there to here

After getting the hang of the R100RS the riding bug quickly sunk it's teeth in and as my motor cycling clock got in sync with the 21st century I realized there was a whole new world of bikes out there -and it would only be a matter of time before the wallet would fall open again to buy something newer.

I managed to hold back for quite a long while, concentrating on restoring and improving the R100RS, while reading up and saving the pennies (and occasionally drooling). I was pushed over the edge in the first couple of months of 2003. I'd spent the winter months putting lots of time and effort into the R100RS and then, once it was all clean and shiny it became really hard to take it out and get it dirty -it's a dreadful affliction and I hope you never suffer from it. The only way out was to buy something that I wouldn't mind riding in the wet.

For a long while I'd been set on changing to a K series bike but I liked the big twin and moving on from an airhead to an oilhead was a fairly logical step, as was the idea of moving from the older to the newer generation "sport-tourer". My mind was made up and I've had no regrets about finally opening that wallet for an R1100RS.

The RS was of '94 vintage with 21000 miles on the odometer. It had had a string of owners but still looked in fine shape -not a mark on the bodywork and the only blemish was on the front of engine where the powder coat was lifting. Riding it home I was surprised to discover the clutch could be made to slip by grabbing a handful of throttle in top gear. Replacing it took a couple of weekends but it wasn't hard to do and only cost around Ł140. From that point on the bike went like a dream and needed little further work apart from the usual servicing.

The RS got plenty of use through 2003 -trips out most weekends, Cardiff to Bristol commutes a couple of times a week as an antidote to sitting in the car in the traffic queues, and of course my first trip abroad on two wheels. Things were going well until my wrists began to get very sore from the forward riding position, a problem that seems relatively common amongst RS owners. The problem gradually worsened to the point of being unbearable. One option would have been to fit bar-backs but the fact that I was also gradually being lured by the thought of an RT pushed me to sell the bike early in 2004.

The replacement was a silver '98 1100RT with ABS, radio, electric windows, heated grips. The bike had covered about 18000 miles and was in lovely condition. The mileage was “about 18000” because it had been first registered in Germany and imported to the UK by SPC Motorcycles. The original Km odometer had been replaced with one measuring miles but all the paperwork was complete, including the original German registration documents.

At first I wasn't at all sure about the riding position -high up, much more upright than the RS, with a hard seat that seemed to slope forward jamming my nuts against the tank. On the other hand the fairing was just what I'd hoped for, proving it's effectiveness immediately on the cold, clear January day that I collected the bike and rode it from Reading back to Cardiff.

How do the older and newer generations compare?

As soon as I started to find out about the 1100s it was clear they are very different bikes from the previous generation -yes, they have a flat twin engine, yes they have a single plate dry clutch, constant mesh gearbox and a shaft drive but they also have fuel injection, 4 valve heads, telelever front suspension, ABS, decent electrics... the list goes on. So after the R100RS the R1100RS was a great new experience -but it also revealed some of the huge changes that had taken place in motorcycle technology between the '60s and the 90's. The biggest difference was getting used to the fact that several of the main systems have microprocessor control and you have to acquire a whole new set of knowledge to do things like adjust throttle position sensors, and from time to time read stored fault codes and clear them from memories. Despite the differences from the older generation it did seem remarkably familiar e.g. the engine had more poke but the torque / power delivery characteristics were similar; it had fuel injection but you still needed to get involved with balancing the engine.

Riding the bike

The R1100xxs are decent mile-eaters but they are fairly "long legged" -great to ride on motorways, better on A and B roads and perfect for touring in all weathers (not as warm around the ankles as the old 100RS). In my opinion they are less good for round town, stop/start use, partly because of gearing, tendency to surge at lower revs and the fact that they're fairly fat, which prevents filtering in really tight spaces. That all said I regularly commute between Cardiff and Bristol on my 1100, a round trip of about 85 miles, almost all on the M4 and it's well suited to the task. Like much of the UK road network there are often holdups and despite being a pretty fat bike I have no difficulty filtering between the lanes of stationery cars (I usually use a rucksack rather than panniers when commuting, so as long as the mirrors fit through the gap then the rest of the bike will).

What gives them "character"?

Oh, all sorts of things. The engines have a tendency to surge, the RS made my wrists ache (badly), the RT has a very uncomfortable seat (at least for my backside), the headlights are weak. These bikes also make a lot of mechanical noise from the engine and gearbox -rattles, clunks and whines, each of which can cause worry and distress until you work out "they all do that". Apart from the legendary noisy gearchange the 'box on the '94 RS whined so loudly in 2nd and 3rd that it was just about all you could hear when sitting on the bike. The later RT benefits from some upgraded gearbox bearings but is still wickedly noisy.

The engines are likely to have a number of distinct rattles...

Starting up: The camchain clatters for about two seconds until the oil pressure builds up sufficiently to tension the tensioner.

When it's been running for a minute but not yet warm: A quite distinct rattle can be heard with the throttle just off idle. It's hard to work out what it is but... After tinkering with valve clearances, end float and cam chain tensioners it finally dawned on me that the noise was coming from the RHS throttle body. This was confirmed using a "screwdriver stethoscope" and I put it down to a noisy injector. One day while doing a throttle sync I happened to just touch the RHS throttle and lo and behold there was the noise -and even better I could make it come and go at will with gentle prodding. It was the butterfly chattering in tune with the intake pulses, which I guess indicates some wear in that department (35000mls)...and to support the "they all do that" theory... a long while back one of the guys at Motorworks had mentioned that RHS butterflies had a tendency to wear and rattle but I'd never connected it to this particular noise up to this point ... and my 1100RS did the same thing too.

When you sit idling in neutral after riding for a while (nice warm transmission): The gearbox rattles. I understand it's interference between the cogs -they're clicking against one another. Common advice is to fill the box with the heaviest mineral oil you can -our cousins in the US seem to swear by Redline Shockproof. I use Castrol Syntrax (synthetic), which is a bit on the thin side and tends to make the rattles louder but makes the gearchanges smoother.

Are they reliable? can you maintain them?

At the time of writing I had covered about 11k miles on the RS and 23k miles on the RT. No problems yet on the open road. The only major problem on the RS was a worn out clutch and so far on the RT I've only had to fix a leaky front master cylinder seal and replace worn rear pivot bearings. All these jobs were easy enough to carry out myself (with some help from the BMW SportTouring website and the BMW repair manual).

Standard maintenance tasks are all straightforward enough e.g. oil, brake pads, brake fluid, throttle sync etc.

Clutch

The 1100RS needed a new clutch when I first got it. The bike wasn't unrideable -I rode it back from Luton to Cardiff, but you could easily get it to slip by giving it a handful of throttle in top gear. After the older bike I didn't have too many qualms about changing the clutch myself so I merrily dug in. I'd been used to the idea of removing the gearbox in a couple of hours and was more than a little surprised to find it took a whole day (!) to get the seat and rear subframe off. Despite the initial surprise I found that removal of the driveshaft, gearbox and clutch was indeed very similar to the older bikes. I've since discovered -in fact the BMW maintenance manual recommends, that you leave the rear subframe attached to the bike and just tilt it up when removing the gearbox / clutch. I'm sure this would have saved a half day's work and that's what I'll do next time. The clutch was well worn at 21K miles. Given the bike's age (9 years) and relatively low mileage I can only assume it had seen a lot of round town riding. Additionally the clutch lever free-play adjustment was insufficient; these two factors together probably accounted for the relatively early (in mileage terms) demise.

The dreaded surging and zero = zero

IMHO surging can be minimized by ensuring correct TPS setting, correct throttle body balance, single electrode sparkplugs, and (if the bike has a catalytic converter) ditching the cat code plug.

TPS setting appears to be critical and Rob Lentini's zero=zero article has been widely quoted, and successfully used by many oilhead owners to reduce surging problems. I have no argument with the theory but having followed the procedure on both the RS and RT have found a shortcoming in the practice. The zero=zero article and its author are well respected and I'm happy to have my opinions ignored or flamed but my experience might just help someone else who discovers the same shortcoming on their bike.

So what am I going on about? The goal of zero=zero is to correctly align the TPS with the throttle butterfly, thus aligning the fuel injection map and the throttle position. The critical first step is to determine exactly where the zero position is, and the simple answer is to say that zero is at the point where the LHS butterfly is completely closed.

Unfortunately on the two bikes I've worked with it's been impossible to get the butterfly to consistently come to rest at the exact same spot when closed, or in other words it has been impossible to determine exactly where zero is. This could be observed through the DVM measurement of the TPS output voltage, where the voltage with the butterfly fully closed would vary by around .008V, depending on whether the butterfly was a allowed to close gently or snapped shut. The variance appears to be caused by interference between the butterfly and the surrounding walls of the throttle body as it approaches fully closed i.e. it fills the bore in the throttle body tightly; factors such as wear, grime and machining tolerances therefore influence exactly where the fully closed position is. In reality the variance in the fully closed position may only be a fraction of a degree but given the precision the procedure calls for it is significant.

The first couple of times I tried the procedure I used the position where the butterfly stops when the throttle is closed gently as zero, locked the TPS and moved on to idle adjustment. With the LHS throttle stop screw set so the TPS was at .037V. the idle speed was too high and couldn't be brought down to 1100 rpm with the air screws. The zero=zero instructions mention this can happen and advise correcting it by backing off the throttle stop screws until the correct idle speed is achieved. If the 1100 rpm = .037V relationship is true then zero must have been incorrectly set.

The bottom line here is that on the two bikes I've worked on there was no single point that could be accurately identified as "zero" and therefore the rest of the procedure could not be relied upon.

Whilst it was not possible to accurately determine the zero position or get the throttle butterfly to reliably close to the same point I found that the idle screw setting was reliable i.e. the throttle could be snapped shut or closed gently and the TPS output voltage would always be the same in the closed (idle) position. So what if the setup procedure was based around the idle setting rather than the zero setting? i.e. 1100 rpm and .037V on the TPS. This is entirely possible but has to be tackled as an iterative process. The steps are:

1. Prepare:

slacken off the throttle cables
loosen and back off the throttle stop screws
open brass air screws to 1.5 turns
warm the engine
get a big fan blowing to prevent overheating
attach the vacuum balancer to the throttle bodies

2. Adjust: loop around the next 5 steps to iteratively set the idle and TPS voltage

set the TPS so it's output voltage is .037V
adjust the throttle stop screws until the engine speed is 1100 rpm and balanced
check and readjust the TPS for .037V
readjust the throttle stop screws, engine speed and balance
keep going round the loop until all three conditions are true: .037V, 1100rpm, balanced

I have no idea if this results in correct, "to the book" TPS alignment but I can say that I've managed to use the approach successfully and have achieved better results than by following the original zero=zero procedure. Try it if you're having problems figuring out exactly where "zero" is -you may be pleasantly surprised.

What was that about headlights?

The 1100s don't have very good headlights -they're standard H4s but the beam is not well focused and doesn't give the impression of being very bright. For some reason the RS seemed slightly better than the RT but that's probably just my imagination because they both have the same reflector and lens. Another potential problem is created by under-specified headlamp wiring that can reduce the voltage actually delivered to the bulb, and which of course reduces the light output. There's a full write up of this potential problem and a way to fix it at www.ebbo.org. I installed the wiring upgrade and got about a 0.8V improvement in voltage at the bulb, though I can't say it made a huge difference using a standard halogen bulb. A Philips VisionPlus did however make a noticeable improvement over the standard H4, especially on main beam.

A 80/100W standard halogen gave better results still; the beam was still widely scattered but the total light output was considerably increased. I used this bulb without problems for about 6 months but on my trip to Nordkapp it blew and at the same time the headlamp lens developed a crack right across it's width -my guess is the blown bulb and crack were caused by the extra heat from the bulb. To correct the headlamp dip for driving on the right. I'd stuck some black insulating tape on the lens. I suspect this caused the glass to heat up or cool unevenly (think sudden showers) resulting in the break -take a look at the line of the crack. What happened to the bulb? I'm guessing some rain managed to get through the crack in the lens and onto the bulb. On reflection I still think the 80/100W bulb is the brightest so far but it runs very hot and can cause unwanted damage in the wrong hands! The new headlamp lens cost Ł108 so I won't be risking it again and have gone back to the VisionPlus.

Of course lots of people add driving lights and that's yet another possibility for the future... next winter maybe.

Rear pivot bearings

Just before it's 2004 MOT I found some axial play in the back wheel on the RT, which turned out to be the pivot bearings. Popular wisdom says that if you can feel the play when you rock the wheel with your hands at 10 to and 20 past then it's probably the bearings. My first go at fixing it was to adjust the bearings. I backed out the adjustable pivot pin on the inner side of the swing arm, cleaned the loctite off the threads and tightened it to the specified setting. Despite several attempts I couldn't get rid of the play and ended up removing the whole final drive. With full access to the bearings I found the one on the adjustable pivot side was shot -the outer race was scored and wasn't providing a good seat for the inner. I replaced the pair; they were easy enough to ease out with a length of threaded rod and a couple of sockets as a home-made puller and some gentle heating. I left the new ones in the freezer for an hour before installing and they more or less dropped in with just a little help from a rubber hammer. Getting the correct torque on the adjustable pivot took some effort -I tried tightening without loctite on the thread a couple of times to be sure I knew where to stop before going for the final with-loctite setting.

BTW the bike had about 28k miles on it at the time. I was fairly surprised to have the problem with relatively few miles on the bike but a well respected independent BMW specialist in the UK (Jim Cray) told me that it wasn't uncommon to see pivot bearings fail at this sort of mileage.