BMW isetta User manual

11

2

Index
Page
Index ……………………………………………… 3
Forward ………………………………………….. 3
Operations / Introduction ……………………….. 4 – 5
Technical Charts…………………………………. 6 – 8
What Is Where …………………………………… 9
Police and Service Station Information ……….. 10
Driving Controls and Run-in ……………………. 11 – 14
Care of Coachwork ……………………………… 15 – 16
Technical Maintenance …………………………. 17 – 24
Ignition Adjustments …………………………….. 25
Carburetor ………………………………………… 26
Clutch, Chain and Brakes ………………………. 27 – 28
Maintenance Schedule ………………………….. 29
Lubrication Chart ……………………………….. 30 – 32
Electrical Diagram ……………………………….. 33 – 34
US Export Lights …………………………………. 35
Forward
The contents of this document were taken from the original owners manual (Instruction
Manual) that my father was given when he purchased his Isetta in 1957. This book and
car has remained in our family since that time. It is somewhat “used” and is showing its
age.
In converting the original booklet to this document, I kept most of the German translation
the same. I find the terminology and use of the English language somewhat amusing.
Where words were misspelled, I made an attempt to correct these mistakes. I also found
several references to figures that were in error and these were also corrected.
In addition to the booklet, I found an insert which I believe was from another document
pertaining to the US Export lighting systems. This information is included at the end of this
document.
Bill Rogers
3

A word of advice
Please don't believe that we want you to
know the contents of this booklet by heart
and don't be afraid by finding a lot of
technical data already on the first pages.
These are mostly written for the technically-
minded Isetta owner, and also for the service
stations. The remaining text, however, should
be read once at least by every driver. In
compiling it we abstained from employing
technical terms and rather adopted an easily
understandable language in which you may
like to talk with your friends about your brand-
new BMW Isetta.
The Motocoupe BMW-lsetta is not an
automobile or a midget car or just a scooter
with weather protection. It is rather a new
solution of the motoring problem. It’s
maneuverability in city traffic, the absolute
weather protection yet permitting a draft-free
open-air drive through a folding roof and
transparent canopy arrangement, its
comfortable interior dimensions, quick
acceleration and considerable top speed by a
high-performance air-cooled engine unit, —
are all advantages which make the BMW-
lsetta a vehicle that we are sure will meet the
motoring trend of a wide public as a safe-to-
handle runabout suitable for city traffic and
country
driving, for field tracks and highways alike.
Excellent road holding and a brake system of
surprising efficiency ensure a maximum of
riding safety. BMW service stations are
organized in the form of a wide net of BMW
agencies and are always at your service. All
shops displaying the BMW sign, shown on
the door of your Isetta will gladly service and
repair your BMW vehicle. You will find
specially trained personnel at BMW Service
Stations, as well as proper tools and a
complete stock of genuine BMW spare parts.
4

Some more explications
The Isetta engine size has been conceived
for performances allowing the Isetta driver to
easily follow the traffic stream. This means,
however, that he must be given momentary
swift acceleration — to pass other vehicles
for instance — as a definite factor
contributing to the driving safety.
Consequently, the Isetta engine has been
designed to provide relatively high speeds
(up to 53 mph) for short instants, a feature
you will appreciate in many situations.
This quick acceleration, however, is not
intended to induce the Isetta owner to
continually run the engine at its possible
maximum speed. The Isetta motor is of the
high efficiency type. It therefore only depends
on you to run it as reasonably as to obtain a
long service life.
Test rides over many 100,000 miles and
numerous testimonials from lsetta drivers
have proved it an acknowledged fact that with
reasonable motoring the Isetta owner
possesses an engine of proverbial reliability.
Now, what's about reasonable motoring?
First the breaking-in or running-in as Britons
say. Make it a rule to strictly follow the
breaking-in instructions! The care devoted to
your engine will pay you unexpected
dividends during its service life. Thus the
breaking-in of high-performance engines is a
rather important matter.
A transfer picture on the windshield quite in
front of your eyes tells you at a glance how
fast you can run in each gear during the
breaking-in period. Bear this well in mind
when driving uphill and above all when
descending a gradient! And another point:
Don't forget to carry out the oil change in
time.
And now the driving after the breaking-in
period. Once done the running-in you may
thoroughly use the efficiency of your engine
unit. The "resistance point" en-countered by
the accelerator pedal, that is the resistance to
be felt at a certain point when depressing this
pedal indicates you to "what an extent you
can depress the accelerator without having to
glance at the speedometer dial. For a jump to
pass another vehicle you can use the full
acceleration capacity without hesitation, but
don't forget to let the gas pedal return to the
resistance point as soon as you have
achieved the passing Jump: That means the
speedometer pointer must soon leave the
red-colored segment that is entered at the 50
m.p.h.-mark.
You can also somewhat exceed the 50 m.p.h.
mark when driving downhill for short periods.
When ascending a gradient depress the gas
pedal to the resistance point only, -
temporarily you can depress it also to its full
extent for a passing jump for instance or on
hair-pin bends, but thereafter the pedal must
return to the resistance point!
When driving away and accelerating step on
the gas pedal slowly and only to the
resistance point. This may cost you some
tenths of a second, but the engine will reward
it on the long run and besides you'll spare
gasoline for the resistance point is also an
economizing position.
The decalcomania on the windshield, in the
direct line of your vision, shows you the
cruising speeds you should not exceed in the
individual gears. The resistance point gives
you a warning and moreover the speed limits
for the various gears are clearly marked on
the speedometer dial. Thus you cannot fail to
do things well.
5

Technical data:
BMW single-cylinder, four-stroke engine, blower cooled
Engine:
250 c.c. engine 300 c.c. engine
Bore 68 mm (2.67 in.) 72 mm (2.83 in.)
Stroke 68 mm (2.67 in.) 73 mm (2.87 in.)
Capacity 245 c.c. (14.83cu.) 298c.c. (18.61 cu. In.)
Compression 6.8 to 1 7 to 1
Power 12 bhp at 5,800 rpm 13 bhp at 5,200 rpm
overhead, in V-arrangement
Valve timing measured at .08 in. valve clearance:
Intake opens 6° after T.D.C.
Intake closes 34° after B.D.C.
Exhaust opens 34° before B.D.C.
Valves
Exhaust closes 6° before T.D.C.
Lubricating system force feed lubrication
Gulch Single plate dry clutch
Engine position Right hand side, transverse behind the seat
Starter 12 volt dynamo starter Noris, LA 12/130 R.
Electrical equipment 12 volt/130 watt generator with voltage regulation
Sparking plug Bosch W 240 T 1
Battery 12V 24 Ah
Carburetor:
Type Bing throttle slide carburetor with starter
1/22 250 c.c. 1/22 300 c.c.
Main jet 130 130
Needle jet 1310 / 6 1308
jet needle 2023 2023
Needle position 1 2
Idling jet 35 35
Pilot air screw opened 1 1/2 to 2 turns 1 1/2 to 2 turns
Starter jet 55 55
BMW four forward speed and reverse gearbox
Gear ratios: Overall gear ratios:
1st 10.05 23.21
2nd 5.17 12.14
3rd 3.54 8.17
4th 2.70 6.1
Transmission:
Reverse 12.15 30.0
Final drive Final drive 2.31 (13/30 teeth) through transverse re-silient
mounted drive shaft and totally enclosed, f ully
adjustable chain drive in oil bath.
Chassis frame: Rigid tubular chassis frame
Axle layout and suspension:
Front wheels Independent front wheel suspension, swinging arms.
coil springs and shock absorbers
Camber 1 1/2 deg.
King pin inclination 5 deg., castor 2.44 in., toe-in 4 to
5 mm = .16 to .20 in., measured on the front border,
and the rear border of the rim.
Rear wheels Narrow axle with suspension by quarter elliptic leaf
springs and telescopic shock absorbers
6

Wheels: Steel disc wheels with split rims 1o facilitate tire
mountin
g
. Rim size 3.00 D -10
Tires: Five tires, size 4.80 x 10"
Tire pressures 17 Ibs. /sq. in. (front), 14 Ibs./sq. in (rear)
Steering: Steering wheel, reduction steering gear, smallest turning circle
approx. 24 feet.
Brakes: Four wheels hydraulic brakes. Brake diameter 7 in.
Total brake lining area 49.9 sq. in.
Track (tread), front 47.2 in.
Track (tread), rear 20.4 in.
Wheelbase 58 in.
Overall length 89.9 in.
Overall width 54.3 in.
Dimensions:
Overall height (unladen) 52.6 in.
Kerb weight approx. 770 Ibs.
Weight:
Carrying capacity 507 Ibs.
Maximum speed: 53 mph.
Climbing ability: First gear 1 in 3
Average fuel consumption: 250 cc engine: 80 miles/lmp.gal. = 67 miles/U.S. gal.
300 cc engine: 76 miles/lmp.gal. = 63 miles/U.S. gal.
Oil consumption: approx. 1.2 litter per 1000 kilometers
Fill-up data:
Fuel tank 2.8 Imp. gal. = 3.4 U.S. gal. with reserve fuel supply
of .65 Imp. gal. (.8 U.S. gal.)
Oil capacity, engine 3.1 Imp. pints = 3.6 U.S. pints
Oil capacity, gearbox 1 Imp. pints = 1.2 U.S. pints
Oil capacity, chain drive .44 Imp. pints = .55 U.S. pints
Fuels and lubricants:
Fuel: Automotive Petrol (Gasoline)
Lubricant: See lubrication chart
Recommended speeds:
Max. permissible cruising
speeds (m. p. h.)
Miles recorded
1st 2nd 3rd 4th
0 to 600
miles 9.3 18.6 28 37.2
Running-in
breaking-in 600 to 2000
miles 11 21.7 34 43.4
After the
breaking-in period Over 2000
miles 12.4 24.8 37.2 46.6 *)
*) Isetta with 300 cc engine 50 mph
Max. speeds for short jumps, (for inst. To overtake another vehicle).
1st 14 mph 3rd 40 mph
2nd 28 mph 4th 53 mph
7

8

9

For police and customs authorities
Serial plate:
Inside at the right in front of the seat
(figure 2 No. 1)
Chassis number:
On front cross member of frame, below
the right-hand door corner figure 2, No. 2)
Engine number:
On engine housing, beside the ignition
coil (figure 3)
For filling stations and workshops
Fuel tank:
In the rear end of vehicle, access
from outside above the license light
nacelle. Capacity 2.8 Imp. gal. = 3.4 U.
S. gal. with reserve fuel supply of .65
Imp. gal. (figure 4)
Engine oil filler:
Oil filler and dipstick on right-hand bottom
side of engine. Maintain oil level always
up to the notch on dipstick. Oil capacity
3.1 Imp. pints = 3.6 U. S. pints. Trade-mark
engine oil SAE 40 in summer, SAE 20 in
winter (figure 5) .
10

11
Driving controls and running-in
You have already learnt at the driving school
how to handle a vehicle. Therefore we think it
unnecessary to repeat all of it. With your
BMW Isetta you have acquired a vehicle
which accommodates all these controls in a
convenient arrangement that makes their
handling a pleasure. The lever for the three-
way fuel line control tap, situated behind the
seat squab, is easily reached with your right
hand (figure 6). When starting from cold, pull
choke lever backwards (figure 7), while the
right hand, turning the ignition key, switches on
the ignition and pushing same in with a further
short clockwise rotation operates the starter
motor. As soon as the engine fires, reset the
choke lever into its foremost position.
Starting engine in cold weather:
a) Turn off fuel before stopping engine,
let engine run until carburetor is
empty.
b) Turn on fuel before starting.
c) Switch off headlamps.
d) Depress clutch pedal to the floor until
engine fires.
e) Do not step on accelerator to start the
engine. At very strong frosts and upon
extended parking in the open air
starting will be easier if battery was
stored in a warm place.
The gear change mechanism works
smoothly, specially if you adopt the habit
not to grasp the gear lever with the whole
hand, but to pull it with the fingers and to
push it with the palm of your hand (figure
8). If the first gear does not engage at
once, release the clutch a bit or clutch and
declutch again for an instant. The heating
for the interior is also controlled with the
left hand by moving for or aft the small
lever situated just beneath the choke lever.
The lighting switch, located below the
steering wheel, is at your easy reach, too,
(figure 9), and the switch for dipping and
raising the headlamp beams is shifted by
the middle finger of your left hand while
holding the steering wheel (figure 10). The
same happens with the directional signal
switch which you can operate with the
middle finger of your right hand without

leaving the steering wheel (figure 11). To
bring the wiper motor in motion, operate the
switch of this unit, fitted to the door beside the
instrument panel (figure 12), and finally let us
mention the seat adjustment procedure.
Having removed the covering board below
the seat, you may slacken the two hexagon
screws and adapt the seat to your
requirements (figure 13). For the other
controls and instruments see “Where Is
What” on page 9.
As to the running-in (breaking-in) of the new
vehicle we refer to the chapter "Some more
explications", page 5, and to the scheme
"Recommended speeds", page 7. These
indicate you the maximum cruising speeds for
the individual gears you should not exceed
during the first running-in period up to 1000
kilometers (600 miles), during the second
running-in period from 1000km to 3000km
(2000 miles) and after the first 3000
kilometers. The running-in speeds are also
shown on the transfer picture fixed to the
windshield of your Isetta. When observing
these speed limits you will in any case avoid
to over-reving your engine.
The red markings on the speedometer dial
show the cruising speeds for first, second and
third. In the fourth gear, the speed range
available within the red-colored section
should be used for short moments only, for
instant to pass other vehicles. A
supplementary spring of the accelerator pedal
facilitates this driving method: You will feel a
slight resistance as soon as the permissible
cruising speed is attained for the gear in
question.
The Motocoupe BMW-lsetta has a wealth of
other fine features. The ventilation of the
interior, for instance, is regulated by means of
the two sliding windows, which have stop-
spring catches to prevent opening from
outside while the vehicle is parked. To open a
window press the button of the locking device
and simultaneously push the window to the
desired position (figure 14). With fair
weather, and the folding roof being opened,
the all round glass paneling provides the
sensation of an open air drive. The folding
roof is opened by
12

operating the lever situated in the middle of
front rail. Please remember that after a rain
the roof must not be opened unless it is
completely dry. To close the canvas hood,
draw the front rail forward and lock with the
mentioned lever (figure 15). At the same time
one opens the front door, so that the
weather-strip will be covered again by the
top-edge of the door. The heating is brought
into operation by moving backwards the
longer lever above the left-hand front wheel
arch. The push-pull rod to direct the air flow
over the floor or to the defroster duct is
located beneath the seat. Knob in front
position = floor heating, knob in rear position
= defrosting (Figure 16). In case a wheel
must be changed removal of spare wheel is
made easier by loosening the seat and
drawing same forward on the side of the
spare wheel. Then lift the spare wheel slightly
from beneath and remove it (figure 17).
Wheel changing does not involve any
troubles. First of all secure in any case the
Isetta to prevent rolling-off and tilting from the
car jack. To change a front wheel, apply the
hand brake, and to remove one of the rear
wheels, secure both front wheels by wooden
blocks or stones. Next remove the spare
wheel and place it within easy reach at the
side of the wheel which it to be changed. Now
remove the wheel cover plate by means of
the screwdriver from the toolkit (figure 18)
and with the wheel nut spanner being also
provided in the toolkit, slacken the wheel nuts
(figure 19). Only then bring the car jack into
position, i.e. below the frame side-member
just before the upward bend (figure 20) for
removal of a front wheel, and under the
engine carrying cross member at the most
accessible inward spot (figure 21) in case
one of the rear wheels is to be changed.
Thereupon remove the damaged wheel
completely by undoing the wheel nuts and
exchange it immediately against the new one.
Tighten the nuts by hand, release the vehicle
from the car jack and solidly tighten again in a
crosswise order. Have a damaged tire
repaired as soon as possible. Tire repairing is
best done by a
13

skilled operator as the treatment of the split
rim requires some special knowledge.
It must be said that the driving manner
influences fuel consumption considerably.
The BMW engine is quite economical and
you will profit by this advantage provided that
you use accelerator and brake pedal in a
careful manner. Every vigorous movement of
your right foot, every full depression of the
accelerator pedal or brake pedal costs fuel.
Therefore, try to adopt the popular smart
driving method, in which the proper gear
changing plays an important part. If after
having attained 25 miles from a higher speed
in city traffic you want to accelerate, this is
best done by shifting from 4th into 3rd, and
engaging the top gear again as soon as your
BMW-Isetta will have regained the proper
speed. If the city speed is generally below 31
miles, stay in third gear at half throttle
opening. In this way you will spare your
engine and you will save fuel.
The BMW engine is designed for high
revolutions and it will not suffer if you raise
the rev. rate in the lower gears in city traffic in
order to get away quicker. With the
remarkable acceleration and the outstanding
maneuverability of your BMW-lsetta you can
easily wind through narrow spaces, so you
may always keep up with the city traffic and
not become one of those unfortunate traffic
obstacles which are a nuisance to all other
road users wherever they happen to appear.
14

Care of Coachwork
The true enthusiast mostly wants to take care
of his vehicle himself, however, the simplest
jobs require some knowledge in order to be
done correctly. The tool kit (Figure 22)
contains all items which you need for
maintenance and minor repairs. The Isetta
washing requires some care and should be
performed by observing the rules outlined as
follows. Chassis and lower part of body
should first be flushed with water from a low
pressure open end hose, to soak off the dirt,
and afterwards a brush should be used. Long
lasting dirt accumulations and dust, often
containing chemical ingredients, would injure
the lacquer. The washing of the varnished
areas should therefore be done when cold,
never wash or polish the Isetta in the direct
rays of sun or while the body is still hot from
having been exposed to sunshine. Apply an
even spray of clear water on the exterior
finish until dirt is soaked off. Do not allow a
strong jet of water hitting the varnished
surface.
Using plenty of water, dirt should be removed
with a clean sponge (fig. 23), the latter being
cleaned at short intervals. Next use the
wrung-out sponge to wipe off all drops of
water and then rub the lacquer dry with a
clean, soft chamois to avoid water spots
(figure 24). Only in case water alone should
not do the cleaning, the finish may be treated
at times with lukewarm water, soapy water (1
to 2 per cent) or shampoos, as the varnish
would become brittle by using them regularly.
After soapy water or shampoo treatment
wash the body thoroughly with clear water
and polish with "Special BMW Hard-gloss
Polish" (figure 25).
15

The finish is well treated when water being
poured upon it is repelled in beads. The
product "BMW Hard-gloss Polish" is applied
with a soft polishing cloth or polishing cotton,
in small quantities upon the completely dry
finish, doing only a small area at a time. Next
dry the body and then rub it down, using a
clean polishing cloth, until original brilliance is
restored.
Light metal parts, such as bumpers, window
Frames, etc. which have become opaque or
spotted should be coated with a chromium-
nickel polish and then be polished with a
clean, soft linen cloth or wad until the original
brilliance is restored (fig. 26).
The maintenance of the canvas hood is easy,
if carried out correctly. Dust is removed with a
soft brush and from time to time one cleans
the canvas hood with a washing brush, using
plenty of water (figure 27). Never try to
remove spots with gasoline or other chemical
products, but rather use good textile cleaner
for this purpose in the same manner as you
would use it for removing spots from clothes.
Care should be taken on the maintenance of
the window panels. All windows are of
toughened safety glass. The adherent dust is
removed with a duster, or best with plenty of
flowing water by means of hose and sponge.
Rub them dry with a chamois skin, but never
with a linen cloth.
To remove the seat from the vehicle in order
to carry out interior maintenance there is a
little trick. First remove the spare wheel in the
manner as already described. Then fold the
seat and turn it right into the gap which
contained the spare wheel. Now draw the
seat on its left corner forward, raise and
remove in upward direction (figure 29).
16

Technical maintenance
While you only need some enthusiasm and
the necessary time to keep your Isetta
looking smart and to clean it, the technical
maintenance requires some special know-
ledge. Therefore the following jobs should
only be carried out by yourself, if they can be
done well. It starts already with the oil change
in the engine which is to be carried out every
1000 miles (figure 30) while engine is hot.
Then proceed to unscrew the drain plug at
the bottom of crankcase (also figure30).
After the last traces of old oil have dropped
out, fill in the new up to the height of the level
mark on the dipstick (figure 5, page 10). (But
do not forget to replace and to tighten the
drain plug before refilling.) The oil capacity is
3.1 Imp. pints = 3.6 U.S. pints.
Draining should take place with the oil still
being warm. On no account use flushing oil to
flush the engine, but rather let engine some
minutes run with a pint of engine oil and then
flush through. Likewise, while the oil is still
warm, it should be drained from transmission
and chain drive. The transmission drain plug
is reached from the side opposite the engine,
at the bottom of gearbox case (figure 31
left). The transmission filler plug is located
somewhat hidden below the air filter in front
of the fender of the right-hand rear wheel
(figure 31 right). Upon having drained the
transmission oil and well tightened the drain
plug, fill in transmission oil through the filler
orifice until it can be seen in the filler hole.
The tapping-up should be done in the same
manner. Oil capacity approx. 1 Imp. pint. The
oil level of the chain case and rear axle
assembly is checked through the filler orifice
in the rear axle unit (figure 32). The oil
should reach the lower threads of the plug
hole. The drain plug is situated just beneath
the filler orifice and is marked by an arrow in
figure 32. The oil capacity of this unit is about
1/2 U.S. pint. The BMW-lsetta features
only 9 lubrication points requiring grease
supply by means of a simple grease gun.
17

Each of the new front suspension units
features three grease nipples and one
oil filler plug.
The grease nipples serve to lubricate top and
bottom bearings of each steering knuckle
king pin and the central bearing of the brake
plate (figure 33).
The grease gun should be applied to them
every 1000 miles at Service A (give the
central brake plate bearing only one or two
strokes of the gun).
Prior to lubrication remove the old grease on
the adjacent joints with a cloth and then inject
the new grease through the nipple until the
excess grease begins to emerge at the edges
of joints.
Don't remove the emerged grease collar as it
is the best protection against ingress of dirt
and water into the joints and bearings.
The oil filler plug gives access to a small oil
reservoir that lubricates the fulcrum bearings
of the swing arm and the newly introduced
torque arm (figure 35).
Use engine oil SAE 40 for this lubrication
point. Refill initially at 300 miles and
subsequently every 1000 miles at Ser-
vice A. Top up to about the middle of the
filler hole thread.
The mounting of the front springs on the
swing arms and that of the torque arms on
the brake plates is by rubber-bonded bushes
which should not be lubricated. The grease
nipple for the steering shaft is also reached
from underneath of the front (figure 34). The
further lubrication points are the universal
joint at the lower end of the steering
column, accessible by opening the door
(figure 36a), and the shaft for the foot
pedals (figure 36b). Contrary to the firstly
mentioned lubrication points the emerged
grease is properly removed on these two
latter points as they are located within the
body and do not get splashed by dirt and
moisture.
Moreover the joints lacking grease nipples,
such as the door hinge pins, the yoke pins on
the linkage mechanism of the pedal shaft,
and all other parts causing friction should be
given a few drops of oil from time to time (see
lubrication chart page 32) by means of an oil
gun (figure 37).
18

For the greasing best use a trade-mark
lubricating grease, which should always be
stored in its well-closed container in order to
prevent the ingress of dust and dirt.
After removal of the seat (see page 16 figure
29) the battery is accessible for checking and
maintenance. The battery cover is removed
by lifting the two cover holding springs, right
and left (figure 38). This gives access to 6
plugs, which are unscrewed to add distilled
water. This check should be performed every
1500 kilometers (about 1000 miles), i.e. every
4 to 6 weeks. The topping-up with distilled
water (never use battery electrolyte) is done
by means of a clean container with a rubber
filler plug, which can be obtained for a few
pennies in an accessory shop, bringing the
level in each cell to approximately 10mm (.4")
above the plates (figure 39). Coat the clean
posts and terminals with light grease or
Vaseline to prevent corrosion (figure 40).
The tire pressures should be checked at
shorter intervals, every 300 miles at least or
once every week. If this is performed with
your own tire gauge (figure 41) test from time
to time with a calibrated tire gauge at a filling
station in order to control the correct
functioning of your own gauge. The tire
pressures should be adjusted to 17lbs./sq. in.
(front) and 14lbs./sq. in. (rear). If one always
rides alone a front tire pressure of 15.6
Ibs./sq. in. will be sufficient. The pressure
difference between the two rear wheels or the
two front wheels
19

should not exceed a value of 1.4lbs./sq. in.
When changing wheels round they should no
be switched diagonally, but from front to rear
and vice-versa, simultaneously at left and
right (figure No. 42).
Among the periodical maintenance items
figures also the care of the air cleaner. This
filter is of the dry element pattern and should
be cleaned every 4000 miles. To do this
disengage the rubber hose clip on carburetor
by means of a screwdriver and push rubber
tube away from carburetor (figure 43, left).
Next loosen the toggle-action clips on filter.
For this purpose grip the air-cleaner body and
snap back the toggle-action clips. Then clean
the filter by dropping same several times on a
wooden block in order to expel the dust
(figure 43, right).
The filter element should be replaced every
7500 miles (see Service C). To carry out this
replacement slacken the fixing screw with a 9
mm spanner, remove cleaning element and fit
a new element (figure 44).
The transmission of movement from clutch
pedal to clutch unit, from accelerator pedal to
carburetor, and from air lever to carburetor
takes place by means of Bowden cables.
These Bowden cables should also be
checked from time to time and lubricated, if
necessary. These jobs, however, are best
done by a BMW Service Station. They should
be performed at intervals of about once a
year, i.e. every 7500 miles, as indicated in the
maintenance chart, and therefore belong to
the maintenance items of Service C (page 29
and appendix).
Finally there is a further maintenance job
which should be carried out every 7500 miles
(also see lubrication chart on last page). The
grease loads in the ball bearings diminish at a
very slow rate, so that the grease in the front
wheel bearings must be renewed from time to
time, only. For this purpose remove the wheel
cover plates and with a clean finger press
clean
20