View Single Post
  #5  
Old 10-Apr-2004, 01:15
Iconic944ss's Avatar
Iconic944ss Iconic944ss is offline
Registered Forum User
WSB Hero
Bikes: 1993 - 944SS & Aprilia Falco
 
Posts: 7,795
Join Date: Oct 2002
Fault finding

Well here goes.....some stuff copied from that book you bought and lost, right

Can do more but was getting shouted at - at this point !!!

Good Luck !!!!!!!!!!!!!

Fault Finding
1 Engine doesn't start or is difficult to start

Starter motor doesn't rotate ?


*Engine kill switch OFF.
*Fuse blown. Check main fuse and starter circuit fuse (Chapter 8).
*Battery voltage low. Check and recharge battery (Chapter 8).
Starter motor defective. Make sure the wiring to the starter is
secure. Make sure the starter relay clicks when the start button is
pushed. If the relay clicks, then the fault is in the wiring or motor.

*Starter relay faulty. Check it according to the procedure in Chapter 8.
Starter switch not contacting. The contacts could be wet,
corroded or dirty. Disassemble and clean the switch (Chapter 8).

*Wiring open or shorted. Check all wiring connections and
harnesses to make sure that they are dry, tight and not corroded.
Also check for broken or frayed wires that can cause a short to
earth (see wiring diagram, Chapter 8).

*Ignition (main) switch defective. Check the switch according to the
procedure in Chapter 8. Replace the switch with a new one if it is
defective.
*Engine kill switch defective. Check for wet, dirty or corroded
contacts. Clean or replace the switch as necessary (Chapter 8).

Starter motor rotates but engine does not turn over

*Starter motor clutch defective. Inspect and repair or replace (Chapter 2).
*Damaged idle or starter gears. Inspect and replace the damaged parts (Chapter 2).

Starter works but engine won't turn over (seized)
*Seized engine caused by one or more internally damaged components. Failure due to wear, abuse or lack of lubrication. Damage can include seized valves, camshafts, pistons, crankshaft, connecting rod bearings, or transmission gears or bearings. Refer to Chapter 2 for engine disassembly.

No fuel flow
*No fuel in tank.
*Fuel pump failure (see Chapter 3 for Monsters and Chapter 8 for
SS/SL models).
*Fuel filter blocked (see Chapter 1).
*Fuel tank breather hose (SS/SL models) or breather hole in filler
cap (Monster models) obstructed.
*Fuel line clogged. Pull the fuel line loose and carefully blow
through it.
*Float needle valve clogged. For the valve in both carburettors to
be clogged, either a very bad batch of fuel with an unusual
additive has been used, or some other foreign material has
entered the tank. Many times after a machine has been stored for
many months without running, the fuel turns to a varnish-like liquid
and forms deposits on the inlet needle valves and jets. The
carburettors should be removed and overhauled if draining the
float chambers doesn't solve the problem.

Engine flooded
*Float height too high - refer to the Note in Chapter 3.
*Float needle valve worn or stuck open. A piece of dirt, rust or other debris can cause the valve to seat improperly, causing excess fuel to be admitted to the float chamber. In this case, the float chamber should be cleaned and the needle valve and seat inspected. If the needle and seat are worn, then the leaking will persist and the parts should be replaced with new ones (Chapter 3).
*Starting technique incorrect. Under normal circumstances the machine should start with little or no throttle. When the engine is cold, the choke should be ON and the engine started without opening the throttle. When the engine is at operating temperature, only a very slight amount of throttle should be necessary.

No spark or weak spark
* Ignition switch OFF.
* Engine kill switch turned to the OFF position.
* Battery voltage low. Check and recharge the battery as necessary
(Chapter 8).
* Spark plugs dirty, defective or worn out. Locate reason for fouled
plugs using spark plug condition chart and follow the plug
maintenance procedures (Chapter 1).
* Spark plug caps or secondary (HT) wiring faulty. Check condition.
Replace either or both components if cracks or deterioration are
evident (Chapter 4).
* Spark plug caps not making good contact. Make sure that the
plug caps fit snugly over the plug ends.
* Ignition control unit defective. Check the unit, referring to Chapter 4
for details.
* Pick-up coil defective. Check the unit, referring to Chapter 4 for
details.
* Ignition HT coils defective. Check the coils, referring to Chapter 4.
* Ignition or kill switch shorted. This is usually caused by water,
corrosion, damage or excessive wear. The switches can be
disassembled and cleaned with electrical contact cleaner. If
cleaning does not help, replace the switches (Chapter 8).
* Wiring shorted or broken between:
a) Ignition (main) switch and general relay
b) General relay and engine kill switch (or blown fuse)
c) Engine kill switch and HT coils
d) Ignition HT coils and spark plugs
e) Ignition control units and pick-up coils
f) Ignition control units and HT coils
* Make sure that all wiring connections are clean, dry and tight. Look for chafed and broken wires (Chapters 4 and 8).

Compression low
* Spark plugs loose. Remove the plugs and inspect their threads. Reinstall and tighten to the specified torque (Chapter 1).
* Cylinder head not sufficiently tightened down. If the cylinder head is suspected of being loose, then there's a chance that the sealing surfaces are damaged or that a cylinder stud has broken. The head nuts should be tightened to the proper torque in the correct sequence (Chapter 2).

* Improper valve clearance. This means that the valve is not closing completely and compression pressure is leaking past the valve. Check and adjust the valve clearances (Chapter 1).
* Cylinder and/or piston worn. Excessive wear will cause compression pressure to leak past the rings. This is usually accompanied by worn rings as well. A top-end overhaul is necessary (Chapter 2).
* Piston rings worn, weak, broken, or sticking. Broken or sticking piston rings usually indicate a lubrication or carburation problem that causes excess carbon deposits or seizures to form on the pistons and rings. Top-end overhaul is necessary (Chapter 2).
* Piston ring-to-groove clearance excessive. This is caused by excessive wear of the piston ring lands. Piston replacement is necessary (Chapter 2).
* Cylinder head warped. This is caused by overheating or
improperly tightened head nuts. Machine shop resurfacing or head replacement is necessary (Chapter 2).
* Valve not seating properly. This is caused by a bent valve (from over-revving or improper valve adjustment), burned valve or seat (improper carburation) or an accumulation of carbon deposits on the seat (from carburation or lubrication problems). The valves must be cleaned and/or replaced and the seats serviced if possible (Chapter 2).

Stalls after starting
* Improper choke action. Check the choke operating cable and
choke linkage on the carburettors (Chapter 3).
* Ignition malfunction. See Chapter 4.
* Carburettor malfunction. See Chapter 3.
* Fuel contaminated. The fuel can be contaminated with either dirt
or water, or can change chemically if the machine is allowed to sit
for several months or more. Drain the tank and float chambers
(Chapter 3).
* Intake air leak. Check for a loose joint at the carburettor inlet
ducts, loose or missing vacuum gauge adapter screws or hoses
or loose carburettor tops (Chapter 3).
* Engine idle speed incorrect. Turn idle adjusting screw until the
engine idles at the specified rpm (Chapter 1).

Rough idle
* Ignition malfunction. See Chapter 4.
* Idle speed incorrect. See Chapter 1.
* Carburettors not synchronised. Adjust carburettors with vacuuaj
gauge or manometer set as described in Chapter 1.
* Carburettor malfunction. See Chapter 3.
* Fuel contaminated. The fuel can be contaminated with either dirt
or water, or can change chemically if the machine is allowed to sit
for several months or more. Drain the tank and float chambers.
(Chapter 3).
* Intake air leak. Check for a loose joint at the carburettor inlet
ducts, loose or missing vacuum gauge adapter screws or hoses
or loose carburettor tops (Chapter 3).
* Air filter clogged. Replace the air filter element (Chapter 1).

2 - Poor running at low speeds

Spark weak

* Battery voltage low. Check and recharge battery (Chapter 8).
* Spark plugs fouled, defective or worn out. Refer to Chapter 1 for
spark plug maintenance.
* Spark plug cap or HT wiring defective. Refer to Chapters 1 and 4
for details on the ignition system.
* Spark plug caps not making contact.
* Incorrect spark plugs. Wrong type, heat range or cap
configuration. Check and install correct plugs listed in Chapter 1.
* Ignition control unit defective. See Chapter 4.
* Pick-up coil defective. See Chapter 4.
* Ignition HT coils defective. See Chapter 4.

Fuel/air mixture incorrect

* Pilot screws out of adjustment (Chapter 3).
* Pilot jet or air passage clogged. Remove and overhaul the
carburettors (Chapter 3).
*Air bleed holes clogged. Remove carburettor and blow out all
passages (Chapter 3).
* Air filter clogged, poorly sealed or missing (Chapter 1).
* Air filter housing poorly sealed. Look for cracks, holes or loose
clamps and replace or repair defective parts.
* Fuel level too high or too low - refer to Note in Chapter 3
concerning float height.
* Fuel tank breather hose (SS/SL models) or breather hole in filler
cap (Monsters) obstructed.
* Carburettor inlet ducts loose or gasket leaking. Check the inlet
duct adapters for cracks, breaks, tears or loose clamps. Replace
the adapters if split or perished.

Compression low
* Spark plugs loose. Remove the plugs and inspect their thread; Reinstall and tighten to the specified torque (Chapter 1).
* Cylinder head not sufficiently tightened down. If the cylinder head is suspected of being loose, then there's a chance that the sealing surfaces are damaged or that a cylinder stud has broken. The head nuts should be tightened to the proper torque in the sequence (Chapter 2).
* Improper valve clearance. This means that the valve is not completely and compression pressure is leaking past the valve. Check and adjust the valve clearances (Chapter 1).
* Cylinder and/or piston worn. Excessive wear will cause compression pressure to leak past the rings. This is usually accompanied by worn rings as well. A top-end overhaul is necessary (Chapter 2).
* Piston rings worn, weak, broken, or sticking. Broken or sticking piston rings usually indicate a lubrication or carburation that causes excess carbon deposits or seizures to form on the pistons and rings. Top-end overhaul is necessary (Chapter 2).
* Piston ring-to-groove clearance excessive. This is caused by excessive wear of the piston ring lands. Piston replacement necessary (Chapter 2).
* Cylinder head warped. This is caused by overheating or
improperly tightened head nuts. Machine shop resurfacing & head replacement is necessary (Chapter 2).
* Valve not seating properly. This is caused by a bent valve (from over revving or improper valve adjustment), burned valve or seat (improper carburation) or an accumulation of carbon deposits on the seat (carburation, lubrication problems). The valves must be cleaned and/or replaced and the seats serviced if possible (Chapter 2).
Quote+Reply