With the introduction of the / 6 Series in 1973, BMW missed the mid-range that were also interesting (and affordable) for younger motorcyclists. So the BMW R45 and the R65 were conceived.
The motorcycle world was buzzing with rumors
But BMW had a number of self-imposed restrictions. The decisive factor was that the Germans could not say goodbye to the cardan drive, so that a motor placed lengthwise was a 'must'. An air-cooled V-twin would look too much like a Moto Guzzi, while a liquid-cooled V-twin would be scornfully dismissed as a Honda CX 500 clone. It was finally decided to simply make an air-cooled boxer block for the newcomers. And as a motorcycle for the youth, the machine had to be affordable, but with the same solidity that the brand was used to. Then so 'der Vati' also have peace with it. The first did not work ...
The new engine was really new. All other BMWs at the time had the same crankshafts with a stroke of 70,6 mm, but the R 45 got one with a stroke of 61,5 mm. The bore amounted to 70 mm, so that the cylinder capacity reached thick 473 cc. The smaller stroke made the newcomer 56 mm narrower than the larger models. The R 45 came on the market in 1978, together with its sister model R 65, which came to 82 cc thanks to a bore of 649,6 mm.
Lost on price and dynamics
The R45s were ultimately more expensive and heavier than the Japanese competition, but they were of better quality and more complete. Opposite was the hacky shift mechanism of the BMWs. The smooth operation of that box was a trick that quite a few (starting) motorcyclists but did not get the hang of it. The limited engine power had a hard time with the 205 kg heavy machine plus driver. The short wheelbase and the low center of gravity provided pleasant, lively steering behavior, but 'nice erasers' were not possible with 35 hp. However, the 27 horsepower insurance class ensured that in Germany a large percentage of competing Japanese and Italian models had also been reduced to 27 horsepower, as a result of which this power shortage did not really play a role.
The R45 was thus in a "normal" (35 hp) and a 27 hp version on the German market. Most of the 27 hp version were sold. And part of that also ended up in our country. In the 27 hp class, the Yamaha SR 500 was BMW's biggest competitor. But the Yamaha and the BMW had the same problem: they couldn't run at high speed for long periods of time. The Yamaha had camshaft problems due to too little lubrication and sometimes a jam, the BMW had to make too much revs, causing the valves to float and sometimes even hit the piston.
The machines that are not driven because they were treated properly were usually from - yet again - older BMW drivers who did not have the money for a big boxer, but did have respect for the brand. The BMW R45 has long been the cheapest way to drive a used BMW. Simply because nobody was interested in it. But in the meantime, the slow, high-revving 450 cc boxers are sort of discovered.
Currently, the price indication for a spotless R45 is around 3.500 euros. And for 2500 euros, firm demands can already be made.
There were two versions of the R 45; the R 45 N, with 27 pk, and the R 45 S, with 35 pk. The "N" was not officially delivered outside of Germany. He was also supplied the R45 as a service bicycle for public servants. With the full cockpit, the TIC (touring integrated cockpit) version, it is even supplied as a police engine.