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1990 BMW R100GS Dakar

Filtering by Category: garage update

A Shocking Transformation

Classic Velocity

After suffering for a long time with bad rear suspension, i decided to send the rear Fox Twin Clicker off to rebuilder Jamie Daugherty. Several weeks later it returned. It did not look any different, but boy did it work different ! The wallowing in the corners was instantly gone. The excessive dive under braking was significantly reduced. The rebound was...well....rebounding. It is amazing how much of the front end handling is dependent on the rear end. I took a trip over to Van Zant airport to log a few miles on a beautiful day. I played with the settings a bit and they actually adjusted the handling versus doing nothing previously. I had a nice chat with a few folks who were at the airport, and watched a few biplanes take off and land before getting back on the road. The damaged roads were the perfect test, and the bike was running perfectly. 



New Shoes

Classic Velocity

This must be the year of the tire. I have purchased more tires this year than in the previous 3 years. However, they were all purchased for good reason. The Avon Distanzia tires on the GS were well beyond their "use by" date, and since I was contemplating taking the bike to the national meet in Sedalia, I could not risk them at sustained highway speeds. I needed some dual sport tires that could travel 1000 miles, participate in offroad events, and then make it 1000 miles home. After looking around and reading a bunch of reviews, I settled on Shinko 705s. Many reviewers had changed to them after Distanzias and were reporting great wear, great traction, and great value. 

They arrived a few days later and on they went. After taking it easy for about 20 miles, I began to lean a little further. They held their line quite well, and were a marked improvement over the Distanzias. More compliant and a little less noisy on pavement. I did a little bit of gravel just to get them scuffed up a bit. So far, so good. 

The Pelican Transfer Pt2

Classic Velocity

As previously chronicled, the Pelican case has moved between a few bikes now, and when I put it on the Dakar, I used existing holes to mount it behind the solo seat. Since it is bolted on, I avoided making any new holes in the case, but it pretty much eliminates any pillion possibilities. I needed to take it off for some rack and wiring work, so I decided to investigate moving it back so that a pillion was possible. It turns out that this is non-trivial due to the "lip" on the rear of the Dakar rack. My first thought was just to cut off the lip and weld it back on horizontal to creat a flat surface. It is a structural piece of the rear and would make the bike non-stock, so I decided against it. 

There are many solutions out there in cyberspace and in mailorder space as well. They range from a host of home-brew solutions to commercial solutions from Boxerworks and Hepco Becker. After choking on the commercial prices for solving a pretty basic problem, I decided to visit the hardware store. The other motivation was that in my case, the Fox shock control lives beneath the rear rack, so I could not just clamp things on in one of the most logical locations.

The home-brew solutions all involved creating a platform to make the case level with the rear "lip". I found my solution in some 1.5" boxed channel. It is already full of holes. I then selected a couple of different U-clamps and headed home. $11.67 all told. Once back in the garage, I cut the channel to the needed width, drilled a couple more holes in the bottom of the Pelican, and test fit the assembly. With everything worked out, I took things apart and rattle-canned everything black. Looked ok, and is very sturdy. At some point I will affix a thin sheet of aluminum to the bottom to cover the couple of exposed holes in the case that now exist. 

Braking Bad

Classic Velocity

The stopping power of the R100GS single disc is legendary in how poorly it works. Even in 1990, the single pot Brembo, single disc, and forearm building lever feel, combine to make for less than desirable stopping power up front. The remedies range from easy/marginal improvement to extensive/dramatic improvement. Offroad, I found the brakes ok, but not great. Onroad, they were downright lousy and performed more like the drums on my /2.

I spent some time researching the various options for making things better. The cheapest and easiest is to get better pads. Descriptions of results mostly indicated a little improvement. Other improvements involved the always popular stainless steel brake line, replacing the master cylinder with a 13mm version, changing the rotor, and then complete caliper conversions and replacements. The most popular of this latter solution was the conversion to dual pot brembos from a later K-bike.

After lots of reading and thought, I decided to replace the rotor and pads. The reports are significant improvement, and the change is very easy. I did not like the idea of sourcing/rebuilding another caliper, using adapter brakets, and/or shaving caliper mounting bosses.

I went with the EBC rotor and pads. They are a bit lighter and semi-floating. After the 15 minute change, I took the bike for a ride to bed the pads in and assess the results. I can report that the difference is significant. The stopping power is increased such that front end dive is more of a problem. It is also much smoother, but that is probalbly down to new rotors. What is not improved, is the feel of the brakes. It still takes physical hand power to get the bike stopped. I suspect that only different calipers will change this. Meanwhile, I am pleased with the results and feel much better about stopping the bike on the road.

MOA Wrenching and Riding

Classic Velocity

I had set a goal of using the Dakar to attend the 2011 BMWMOA Rally. A number of things had to come together prior to that. Dave Cushing and Brian Curry sorted out the one pulled head stud that was discovered when the perfect valve clearances still resulted in a loud valve train. And then there was the clutch problem. On a shakedown ride, the bike suddenly had no clutch after stopping at an intersection. The lever and cable were fine, but there was no clutch resistance and I suspected the rod, or something worse. I towed it home, and upon unloading the bike, the clutch was back to normal ! It turns out that it was the actuator at the back of the transmission. It is a known problem that with age, the original piston expands when it heats up and gets stuck. The solution was a replacement with a smaller diameter and the problem was solved.  
Then there was the headlight. One of the plastic retainer clips had broken, and the headlight was rattling around. I stuffed some foam in there initially just to prevent more damage, and then attacked the lighting issue one weekend. Lots of folks upgrade the alternator on the bike, and then add a mega lighting package of some kind. I wanted to add some LED lighting to avoid the whole upgrade process. After looking at some effective but expensive solutions from Clearwater and Twisted Throttle, I decided to invoke my frugal BMW clan member side, and picked up some LED auxillary lights from an automotive store. They installed easily once I got a pait of clamps for the frame, and I am pleasantly surprised at the results. They are very effective, and draw no current. The combination with the headlight has dramatically improved night vision, and the cost was a fraction of the other solutions. However, I am under no illusions about durability on these lights, as one good rock would likely mean game over.
The stock side cases were in good shape, but lost their retainer straps, so I transferred a pair from my other system cases. The Pelican case sat on the tail rack, and the tank compartment had a new lock, so all was right with the luggage world. I purchased one of those LED bulb replacements for the tail light. I don't notice very much difference in brightness during the day, but I am sure it is more effective at night. Lastly, an oil change, and new plugs. You would think that I was going cross country, but this was all planned anyway and just got concentrated into the pre-rally burst of activity.
I took a circuitous route to the rally making it 360 miles to get there. I did about 60 miles offroad, and the rest on tarmac. The bike performed flawlessly despite blistering temperatures in the 90s the whole way. I can say that the heat off the cylinders does not help ! With the softly sprung front end, it does tend to wallow in the corners a bit. I camped at the rally, and saw several other nice examples of Dakars among many other things mentioned in the main blog and elsewhere. I did some day rides including more dirt where the front suspension was much better suited. Some great riding. I took a different route home and added about 200 miles. All in all, I can now declare the bike ready for major duty. I have my eye on a few trips this fall.....

The Pelican Transfer

Classic Velocity

My trusty Pelican case has been on 3 bikes, and I was hoping that somehow the holes already present line up for the Dakar as well. But of course, that was not to be. One more hole was needed, and I reluctantly got out the drill and did the deed. Once on the bike, it did look like it always belonged there, so I was pleased with the results. This makes the bike ready for solo trips, but the mounting interferes with the passenger seat, so no two-up with the case on board. I will look at a more rearward mounting platform later tis summer..... 

U-Break U-Joint U-Fix

Classic Velocity

Note: A longer version of this post can be found in the main blog as Getting the Shaft and other Blessings

The shaft drive of the BMW is a brilliant evolution of a 1920s design. It is sturdy, reliable, and has great benefits over a chain drive. However, the R100GS has gathered a reputation for being hard on u-joints. Some say it is the more acute angles of the shaft required for the GS, some say aftermarket shocks, some say sun spots. Regardless, they have a high failure rate on these bikes, and examination of the shaft every rear tire change is recommended. The front driveshaft u-joint on my bike looked fine only days before, so either I missed seeing a crack, or it went from good to no good during the ride.

With the driveshaft out of the swingarm, the level of his good fortune was obvious. This was the original shaft, and while the rear u-joint was fine, the front had two damaged pivots. The housing was broken, and needle bearings had escaped in every direction like some disturbed ants nest. The amount of play in the joint was excessive. I realized that he could not have been more than a few miles (or a few ft/lbs of torque) away from complete disintegration, or lockup, or some other less than desirable outcome. This was close. Really close. Inside the swingarm were the pieces of the housing and needle bearings. Without cleaning it out thoroughly, I would have been putting a new shaft in with lovely new grease and lots of little pieces of metal ! I grabbed a beverage, sat down, considered the bits of motorcycle all around me, and gave thanks.





A week later, I had a new shaft with circlip equipped u-joints so they are now replaceable. It also has grease nipples, so it is serviceable. Thanks to Bruno's in Canada for the new shaft. The installation was almost a breeze, just pay attention to a few caveats, and reverse the process. Torquing the front driveshaft bolts is a pain without the proper tool. Taking inspiration from online forums, I used a ring spanner with a socket stuffed in the other end and a torque wrench. A bit imprecise, and sure the BMW tool is perfect for the job, but I was determined not to buy another costly use-it-once-every-five-years BMW tool.

While the bike was laid up, I dropped the pan, and removed both petcocks to find both of the reserve tubes clogged ! That would have been a surprise discovered at the worst possible time and place. Igave thanks for that as well. In fact, this whole philosophy of being thankful for the discovery of problems and narrowly avoided disasters, seems well-suited to classic vehicles......