Tuesday, 30 July 2013

cagiva mito 125 problems / troubleshooting / fault finding ideas

cagiva mito 125 troubleshooting / fault finding .

not in any order , and only some basic ideas not comprehensive list
ill update as i find more out and also try to tidy article up one day .

just ideas not comprehensive and not necessary
in order of a sensible test procedure .
will update with new knowledge as i go !!

Engine won’t turn over:
Piston seizure
Con rod small end seizure
Con rod big end seizure
gear seize
main bearing failure

No fuel:
pipes on carb correct
empty tank  ??
Fuel tank lock vent blocked
Fuel tap off
Fuel tap blocked
Fuel line blocked , corroded
Float valve siezed
fuel filter blockage
fuel filter at carb blocked

see our post on fuel problems here 

Engine flooding
Fuel level too high
Float valve worn or stuck open
Starting technique
allow to stand for while before retrying to start
do not keep starter motor engaged for long give it
a rest between trys .

No spark; weak spark:
Spark plug fouled, faulty , or wrong gap
Spark plug cap or high tension wiring faulty
Spark plug cap not in good contact with spark plug
CDI unit faulty
Ignition coil faulty
generator faulty or damaged
Loose wires bad connector blocks
Engine cut out swtich faulty
earth wirse loose/missing/high impedence

see our no spark post here 

Air/fuel mixture incorrect:
Idle air screw maladjusted
air passage restricted
Air filter dirty , leaking  missing or sports
jets blocked or restricted
Incorrect fuel level
Incorrect jet sizes
sports airfilter or exhaust fitted to standard carb
set up
air leaks
reed valve damage
engine not reving properly / spluttering

Fuel level incorrect
Main jet clogged, restricted or wrong size
Throttle valve does not fully open
Air filter dirty /blocked
exhaust tract restricted with deposits
Water or foreign matter in fuel
Ignition timing not set properly
Transmission oil level too high
Transmission oil
viscosity too high
Crankshaft bearing worn or damaged
air leaks inlet


Brakes dragging
Clutch slipping
Transmission oil level too high
Transmission oil viscosity too high
Drive chain misadjusted
Tyre air pressure too 
low Transmission oil level too low
Transmission oil poor quality or incorrect type
Coolant level too low
Coolant old
Coolant not mixed properly
Radiator clogged
Radiator fins damaged
Radiator cap faulty
Water pump not working
Coolant passageways restricted
thermostat failure

see also our post called  Cagiva Mito 125 how to test a thermostat and coolant cooling system / overheating problems

clutch problems

Excessive clutch lever free play
Clutch cable misadjusted or not working smoothly
Clutch steel plates warped
clutch cable / adjusters incorrectly set / need replacing
Clutch spring worn / tension uneven
Transmission oil deteriorated
Transmission oil viscosity too high
Transmission oil level too high
Clutch housing bearing seized

gearbox common problems

incorrectly fitted
missing spacers in gearbox
worn faulty gear bearings
selector arm spring damaged incorrect fitting
bent selector forks levers etc
worn casing bearings
missing circlips

common noises and causes
CDI unit faulty
Carbon built up in combustion chamber or on piston crown
Poor quality fuel or incorrect pre-mix
Spark plug incorrect
Ignition timing not set properly

Overheating Piston slap
Piston to cylinder clearance excessive
Cylinder or piston worn
Connecting rod bent
Piston pin or piston pin holes wornConnecting rod small end clearance excessive
Connecting rod big end clearance excessive
Piston ring worn, broken or stuck
Piston seizure or other damage
Cylinder head gasket leaking
Exhaust pipe leaking at cylinder head connection
Crankshaft runout excessive
Engine mounts loose
Crankshaft bearings worn
Primary gear worn or chipped

Some pages from cagivas Mito workshop manual

see also my cagiva mito will not start

find your workshop manual here

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