BMW R75/5 "On The Lift" Classic Motorcycle Road Test
http://www.clymer.com
Welcome to On the Lift episode two, sponsored by Clymer Manuals. I'm James Grooms, Managing Editor.
We're at the Tech Center today and on the lift we have a 1970 BMW R75/5. The /5 ( slash five ) series, introduced for the 70 model year, was a real watershed bike for BMW motorcycle production. The previous generation of machines [ post war wwII R50 R50/2 /2 R60 R60US R69 R69S ] were known for their reliability, comfort and quiet operation. Once exclusive attributes to BMW, however, many of the new models from Japan [ Honda in particular with the CB350, CB450 and revolutionary CB750 ] now achieved this at a lower price along with impressive performance.
The /5 was available in 500, 600 and 750 cc capacities... this being a 750, thus the R75 designation [ R50/5 R60/5 ]. While relying on BMWs trademark air cooled boxer twin, the model is a radical departure in many ways from the previous models. A telescopic fork replaced the Earles leading link fork. 12 volt electrics replaced a 6 volt system. And to the horror of many a BMW loyalist the bike was available in a color combination other than schwartz mit weiss.
The horizontally opposed twin [ boxer, flat twin or airhead ] with overhead valves was all-new. Outwardly, the first noticeable change from the previous models was the placement of the pushrod tubes under the alloy barrels and cylinder heads revealing that the camshaft is under the crankshaft. [ Yes pushrods! While the world was going with SOHC and in some case DOHC, BMW stuck with camshaft in the crankcase. ] The one-piece alloy crankcase features split type bearings in place of the previous ball bearing setup.
With aluminum covers over the air filter, starter and alternator, the engine appears to be immense. However, everything is alloy and once removed you can see how compact the engine really is. And the heavy forged crank and cam placed low make for a low center of gravity. You can really feel this during low speed maneuverability.
The four-speed gear box is splined to a dry single plate clutch [ /6 on models had a five-speed trans ]. The kickstarter carried over from the older models and as you can see swings out away from the bike. Power is transferred through a swing arm mounted drive shaft to the differential.
The hemispherical heads [ hemi ] are fed on this model with CV or constant velocity carbs [ carburetor ]. R50 and R60 s used Bing slide valve carbs. With the carbs, spark plugs, valves, breaker points, air cleaner and battery easily accessed, and shaft drive, airheads are one of the sweetest bikes when it comes to working on them [ repair manual shop manual maintenance how to DIY camera mount ]
The front brake is an 8-inch twin leading shoe setup. By the early 70's most machines in this class had a disc up front. The rear is a single leading unit.
Looking back the /5 has developed a cult appeal, but at the time it was not universal loved by the purists. Sidecar use wasn't recommended, fiberglass fenders...oh no! And of course the introduction of the chrome tank panels in 72 along with a smaller fuel capacity met with strong disapproval. Now those toaster tank models command higher prices. The result of low production and changing tastes I guess.
Early production 5s could experience a speed wobble and a torque reaction when chopping the speed in a corner. So in 73 they added 2 inches to the swing arm and lengthened the frame. So now you have the short wheel base and the long wheel base bikes and the "which one is better" debate continues to this day. Honestly the SWB bikes just look better and that toaster tank...come on...and I love 60's era vintage Japanese bikes [ like the CB77 Superhawk, CB450 K0 K1 blackbomber Suzuki X6 Yamaha YR1 ]!
Either way they were and still are great machines. The flat twin was considered a dinosaur by many in 1970. Instead of abandoning their heritage [ Germany Germans at their best, Deutschland uber alles !?], BMW took what they knew and created a technical masterpiece that has stood the test of time. This basic layout would be the foundation for 20 plus years and launch the R90S, the R100RS, the R100RT and the R80GS [Manual for /6 R60/6 R75/6 R90/6 /7 R60/7 R75/7 R80/7 R100/7 R90S R100S R100T R100 R100CS R45 R65 R65LS R80ST R80RT R80 R100GS R65GS R100R R80R R1100RS R1100GS R1100R Manual for 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 Clymer manual BMW R50/5 through R100 GS PD M502-3 ISBN 0-89287-854-1] Music by Kevin MacLeod BMWON BMWMOA 5UNITED AHRMA CLYMER CLYMER.COM maintenance troubleshooting repair diy
Autor:ClymerManuals
Tagi:bike R75 cafe vintage R75/5 crash repair classic manual test road BMW motorcycle racer
