Irregular feed of petrol to the carburettor.
Main jet partly clogged.
Carburettor butterfly valve does not open
The float needle does not close properly.
Petrol of bad quality.
The spark plug is not of the right type.
The plug is loose.
The sparking plug cable sparks externally.
The spark gap between the electrodes of
the sparking plug is too wide.
The sparking plug electrodes are dirty.
The contact breaker opening is excessive.
The secondary winding of the coil is
short-circuited or broken (750) -
The silencer is
Clean the carburettor filter, the petrol
cock filter and the petrol pipe.
Clean the main jet by means of an air
Readjust the valve travel by means of
the adjustment screw of the carburettor
Clean out the carburettor and especially
the needle seat.
Empty the petrol tank and refil at a
If the sparking plug overheats, you will
have preignition, knocking, and missing,
especially at high revs. If the sparking
plug remains too cold, you wil have no
ignition, because the electrodes wil
short-circuit. Use the right type of
sparking plug; we advise the use of a
plug having a thermal figure of 260 of
the Bosch international scale.
Tighten the plug down welL. A washer
should always be placed between the
sparking plug and its seating in the
Change the cable or repair the insulation
Adjust the gap to the proper width of
Clean the electrodes with a wire brush.
Readjust the exact opening of the
contact which is 0.3-0.4 mm ~ 0.0118"
Change the coil (at a Oucati Servicing
Clean the silencer, to ensure free dis-
charge of the spent gases.