BMW R45. The smallest Boxer has passed its lowest point

After the presentation of the /6-series in 1973, BMW missed the middle class that were also interesting (and affordable) for younger motorcyclists. So the R45 and the R65 were invented. The youngsters found it too expensive. And too slow… But the market was there (theoretically…)

The BMW R45: an unsellable top model.

In Germany there was the popular 27 hp insurance class. Of course BMW could have used a down-tuned R60/7 there. But compared to the Japanese competition its looks were too old-fashioned to appeal to the intended young target group. And it would be too expensive for the target group. The motorcycle world was buzzing with rumours, but BMW was faced with a number of self-imposed restrictions. The decisive factor was probably that the Germans could not say goodbye to the cardan drive, which made a longitudinally mounted engine a 'must'. An air-cooled V-twin would look too much like a Moto Guzzi, a liquid-cooled V-twin would be disparagingly dismissed as a Honda CX 500 clone. In the end it was decided to simply make an air-cooled boxer block for the newcomers. And as a motorcycle for young people the machine had to be affordable, but radiate the same solidity that people were used to from the brand. Then 'der Vati' would also be at peace with it. The first did not work…

The engine

The new engine block was really new. All other BMWs at the time had the same crankshafts with a stroke of 70,6 mm, but the R45 got one with a stroke of 61,5 mm. The bore was 70 mm, which brought the cylinder capacity to a whopping 473 cc. Due to the smaller stroke, the newcomer was 56 mm narrower than the larger models. That would later make the block quite popular in the various road racing classes, where every centimeter of width gain was seen as a serious gain. The R45 came onto the market in 1978, together with its sister model R65, which came to 82 cc thanks to a bore of 649,6 mm. Quite a few R45 models were upgraded with R65 cylinders (and heads plus carburetors).

The design

The R45 and R65 were designed by Hans Albrecht Muth, who started designing at BMW because he thought the /5 series was ugly and because no one else at BMW was concerned with styling. Incidentally, Muth has little good to say about the current model line. The new machines looked more modern than the /7 series due to their subtly sharper stylized lines. The first press photos showed the R45 with spoked wheels and two disc brakes on the front wheel; the production version got the new cast wheels with only one disc, which were also used in the heavier models. Other changes compared to the existing models were the placement of the brake fluid reservoir for the front brake on the handlebars (this had previously been cable-operated and highly impractical under the tank) and different, more modern counters on the handlebars. The drive train (clutch, gearbox and cardan shaft) was identical to that of the heavier models…

The modifications

In 1981, some modifications were made. The cylinders were given a Nikasil cylinder wall and became lighter, the contact points were replaced by a transistor ignition, the clutch operation became lighter, the oil pan became larger, the lubrication of the crankshaft was improved and the choke lever moved to the handlebars. The air filter was given the new, plastic air filter housing that would also be used on the heavier models.

Lost on price and dynamics

The R45s were ultimately more expensive and heavier than the Japanese competition, but they were better quality with an excellent set of tools and a first aid kit. A plus was that the BMWs were originally equipped with good tires and had good lighting.

The Japanese were not that far yet. On the other hand, there was the choppy gearshift mechanism of the BMWs. Smoothly operating that gearbox was a trick that quite a few (beginner) motorcyclists could not master. The limited engine power had a hard time with the 205 kg heavy machine plus rider. The short wheelbase and the low center of gravity ensured pleasantly lively steering behavior, but 'nice erasing' was not possible with 35 hp. However, the 27 hp insurance class ensured that in Germany a large percentage of the competing Japanese and Italian models were also reduced to 27 hp, so that this lack of power did not really occur in practice.

The R45 was therefore available on the German market in a “normal” (35 hp) and a 27 hp version. The 27 hp version was sold the most, and some of them also ended up in our country. In the 27 hp class, the Yamaha SR500 was BMW’s biggest competitor. But the Yamaha and the BMW had the same problem: they could not drive at high speed for long periods of time. The Yamaha had camshaft problems due to insufficient lubrication and sometimes a seizure; the BMW had to rev too high, causing the valves to float and sometimes even hit the piston.

The result was that the reputation of the R45 did not improve. And that was quite something for a BMW. Incidentally, that quality problem trend is current again with the more recent models, thanks to the duo M&M. Not the sweets, but the managers and marketers.

The machines that weren't ridden because they were treated nicely were usually owned by – yet again – older BMW riders who couldn't afford a big boxer, but did respect the brand. But even when those cherished R45s changed owners, they went for spare change. The BMW R45 was for a long time the cheapest way to ride a used BMW, simply because no one was interested in them. We saw an almost spotless example with cases and a full touring fairing change owners for just €1.200. But in the meantime, the slow, high-revving 450cc boxers have been sort of discovered. And let's face it: there have always been enthusiasts.

The boundary conditions

• The parts supply: Is fine
• The prices of parts: Civilized
• The reliability: Is fine
• Key friendliness: Is fine
• Driving pleasure: Great for a nice tour

The specialists: the Hobbyist, the Knalpot and a whole bunch of other BMW enthusiasts who lost their dealerships years ago after dealer reorganizations at BMW.

Performances

In Germany there were two versions of the R45: the R45N, with 27 hp, and the R45S, with 35 hp. The “N” was not officially delivered outside Germany. Because the R45 was not so dynamic, it was also delivered as a 'Behӧrdemaschine', service bike for government servants. With the full fairing, the TIC (Touring Integrated Cockpit) version, it was even delivered as a police motorcycle.