PIAGGIO X8 125 Workshop Manual page 187

X8 125-200
Engine
loosened the CO value rises (rich mix). Tightening
the screw decreases the CO (lean mix).
- If the adjustment of the flow screw causes a rpm
increase readjust the revs again and if necessary,
the flow screw to reach stable values.
- When the oil temperature, the numbers of revs
and the percentage of carbon monoxide are re-
spected the idle carburetion is considered correct.
From the analyser we can draw further informa-
tion:
- carbon dioxide percentages (CO2), the percent-
age of carbon dioxide has an inverted course com-
pared to the percentage of(CO), values over
12.5% are considered correct. Non complying val-
ues indicate lack of tightness in the exhaust sys-
tem.
- Unburned hydrocarbons (HC) are measured in
parts per million (PPM). The HC value decreases
while the rpm increases; with the engine at idle it
is normal to detect 200 ÷ 400 PPM, these emission
values are deemed normal for an engine with a
diagram of distribution for motorcycles. Higher val-
ues can cause loss of engine blows as the mixture
is too lean (low CO), ignition failure or, incorrect
timing or a clogged or unsealed exhaust valve.
- If it were difficult to ???? adjustment CO check
accurately:
- That the carburettor is clean
- That the automatic starter is efficient
- Tapered pin housing efficiency
- Tank level adjustments
N.B.
THE EXTENSION TUBE IS INDISPENSABLE SO AS NOT
TO SEND POLLUTED EXHAUST FUMES TO THE AMBIENT
OXYGEN. IT IS INDISPENSABLE TO USE AN EXHAUST
FUMES ANALYSER PREVIOUSLY HEATED AND PRE-
PARED TO GUARANTEE THE RESET OF THE READING
OF GASES AND THE CORRECT GAS CAPACITY. FAILURE
TO RESPECT THESE REGULATIONS RESULTS IN INAC-
CURATE READINGS.
N.B.
THE WASTED SPARK IGNITION SYSTEM OFFERS RE-
MARKABLE POWER. READINGS MAY NOT BE ACCU-
RATE IF INADEQUATE RPM INDICATORS ARE USED.
ENG - 187