BMW R 45

The R45 and R65 series, which replaced the larger and older 500 and 6oocc models. Much neater and smaller than its predecessors, the R45 nevertheless still weighs a hefty 4251b, the same as its larger stablemate. Two stages of tune are offered on the R45's oversquare engine, 26bhp for the German market, where it gets into a lower insurance bracket, and 35bhp for the rest of the world.

On the export version, peak power is reached at 725orpm, while maximum torque is 27.51b ft attained at 55oorpm. As is now legendary with these Berlin-built bikes, the engine is of fiat-twin configuration with valves operated by pushrods and rockers. It may not be the most modern layout available on a motor qycle but, over many years, it has been improved and developed so that it is reliable, efficient and very smooth. Performance is not a strong point of the R45 but it will reach a top speed of just on 95mph. Fuel consumption on the other hand is excellent, with an average figure of 55 to 6ompg being possible. The bike has a 4.8 gallon fuel tank, so it is obvious that it was made with touring in mind.

Transmission is by five-speed gearbox and shaft drive, while braking is by a single cross-drilled disc at the front and a powerful drum at the rear. Standard fittings on the bike include cast-alloy wheels, audible warnings for the indicators, twin mirrors, electric starter and a plug for fitting an intercom device. The standard of finish is about as good as can be found on a motor cycle, but there is a price to pay for that: the price itself, for the smallest BMW produced was more expensive than many 750s

Motorcycle Mechanics review 1980

APPARENTLY BMW had a customer who bought one of the new R45 BMWs and after a short time claimed it was faulty but happily compromised by paying the difference to change up to a 650cc R65.
BMW staff could find nothing wrong with the R45. They concluded that the buyer was obviously disappointed with it and accommodated the fresh deal to keep him happy.
A little over 12000 miles with an R45 left me sympathising with the customer. "Remember that it's only a 450," pointed out a BMW executive after I had outlined my findings with this model.

Actually 473cc, its biggest problem is that it just does not want to get off the line. It has to be revved like a petulant two-stroke to get it rolling.
When I first collected it I stalled it three times in quick succession because I did not have enough revs up when slipping out the clutch lever.
At first I couldn't make it out. I thought the engine was not warm enough, or it needed more choke or vice versa. As I got used to it I discovered that with the engine fully warm the problem was less severe, but still remained.
Before becoming too ensconced on this detail it must be said that you can still tour on the R45, two-up with plenty of luggage and maintain a good average speed.
Apart from collecting the bike the first part of the test involved exactly that: a two-up ride to the L?!"1 Histrict as part of a holiday.
On the motorway the BMW was quite at home, if a little short of stride. Induction noise muffled the already passive exhaust note as the fairly accurate speedometer would sway from 70-95mph depending on gradients and winds with the throttle flat against the stop.
The tall, forward leaning riding position, while a little strained in towns, provided the right degree of body cant into the airstream for fast roadwork.
Allowing itself to compress to about half its normal depth the seat became firm but never uncomfortable and there was never any fatigue from vibration. The engine though a high rewer for a pushrod twin was always remarkably smooth.

Fitted with £148 BMW panniers which can be crammed full to make a mockery of the quite rightfully included warning notices about maximum loads, the BMW emerged in the marque's tradditional mould when top gear was in the running.
In town it was decidedly unlike a BMW. It would fire readily enough, though a new start motor had to be fitted while on test,  but needed full choke for an uncommonly long period. This resulted in a stall due to too much choke if the engine was allowed to idle at a road junction, or with the choke off the engine just would not pick up.
Even when warm the engine had to draw a second breath to pass through a "barrier" at 3000rpm. If you allowed yourself to be caught with less than 3000rpm on the rev counter, opening the throttle produced little result until the engine had struggled to get clear of the 3000rpm line.

Since BMW have invariably produced twins which pull from no revs this rev conscious newcomer is a complete surprise, and sometimes a complete embarrassment. The model also desperately needs a quick action throttle. Because of its lack of grunt it has to be revved briskly in the gears to get it to accelerate. When changing up it is difficult without an exaggerated arm movement to throttle off completely from fully open. This results in a jerky upchange if the throttle is not fully closed.

One of the R45 problem's is that it concedes power without an appropriate loss of weight when compared to its bigger brothers. According to the specification it weighs the same as the R65 which in turn is heavier than the R100S, R100T and R80/7!

When the new R45 and 65 models were i first introduced in 1978 BMW stressed that the external dimensions of the R45 and 65 were smaller and that the seat height was "very low". The idea was to capture a wider market for BMW while still retaining the BMW look and tradition.

The result is a handsome machine with a particularly good-looking fuel tank. But overall the bike is only marginally smaller than the bigger displacement models. The German idea of a "very low" seat height is considerably higher than a 750 Triumph Bonneville for example.

There was also the claim that the R45 was a "super-fuel version". The test bike varied from 48.5 to 54.8mpg. During the Land's End to John O'Groats run (featured in MCM in July '79) the BMW R100RS varied from 42.4-55.7mpg and averaged 48.7mpg to the R45's average 52mpg.

The net result is that it is only slightly more economical than BMW's biggest gun.
While the 650 model emerged as a worthwhile addition to the BMW range (tested June '79) the R45's lack of power brings all the above mentioned points to a head. It shares the same 61.5mm stroke as the R65 which might lead one to guess that the 650 was given all the development, the sleeved down 473cc version being an off-shoot to take advantage of favourable European insurance ratings for low horsepower two-wheelers.

Strangely the fuel tank has a tap on one side only. This results in two reserves: the ordinary type and the type where you get off the bike and lean it over to get fuel into the tap half of the tank.

Biggest problem of all for the R45 is that it is a BMW. Because it bears that name a lot is expected of it. In terms of chassis, lighting and so on it is equivalent to the 650. It's the engine's lack of power and flexibility which drags it down.

You have to be very careful about puffing your chest out with pride when someone remarks on your BMW. Not too many people will realise that it is only a 450. You could find yourself swallowing your pride in a series of gulps as the engine repeatedly revs and dies in an awkward attempt to get under way. The R45 fails to live up to BMW's refined image.