Engine Problems, Causes and Corrections

1. Engine does not start or starts poorly
Cause Remedy
Fuel tank empty Fill tank
Fuel petcock closed Open petcock
Throttle grip turned on too far when engine is cold Close throttle grip
Air filter clogged Clean air filter cartridge or replace it
Leaking or clogged fuel line Stop leak in line or blow it out
Defective float needle Replace needle valve
Clogged idling jet Clean jet
Contaminated breaker points Clean points
Loose or defective ignition cable Check cable; replace af necessary
Wet spark plugs due to condensation or too much fuel Clean spark plugs
Breaker contact gap or spark plug electrode incorrect Correct gap
Sticky valve Remove possible should be performed
carbon deposits by an autorized
from valve BMW dealer
Dead battery Have battery charged in service station.
Caution! Charge battery only with + and - cables removed.
2. Engine starts, but idles irregularly
Carburetor set too rich or too lean Readjust carburetor
Valve clearance insufficient Readjust valve clearance
Leaky valve Have valves ground
Leak between cylinder and head gasket or carburetor Check cylinder and should be performed
carburetor connections by an authorized
for leaks BMW dealer
Low compression Have valves ground
Check piston rings
or rebove cylinders
3. Hot engine idles irregularly Exhaust smokes
Float needle valve leaks, idle mixture set too rich Repair valve; readjust idle mixture
4. Engine runs irregularly, stalls Occasionally
Spark plug electrode gap too wide Readjust electrode gap
Oily or sooty spark plug Clean or replace spark plugs
Cause Remedy
Ignition cable wet or defective Dry or replace cable
Spark plug cap shorted Dry or replace plug cap
(recognizable by sooty burned spots)
Defective ignition system Replace defective parts
Clogged carburetor jets Clean jets
Clogged fuel line Clean the fuel line
Condensed water in float bowl Clean float bowl
5. Engine runs excessively hot, keeps running after ignition
is turned off
Fuel mixture too lean Check and readjust carburetor, check jet selection
Timing off Check and readjust ignition
Breaker contact gap off Check and readjust points
Dirty engine cooling fins Clean cooling fins
Spark plug heat value too low Use specified spark plugs
6. Engine pinks under load
Fuel octane rating too low Use name-brand fuel
Heavy oil carbon residues in combustion chamber Clean pistons, for which cylinder head must be removed,
see your BMW dealer
Timing too far advanced Correct timing
7. Starter does not work
Isolation of the gliding ring Press down kick-starter
caused by cold wheather

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