Motorcycle Repair: Engine running hot, kawasaki 454 ltd, combustion chamber engine

Question
I have a 1989 kawasaki 454 ltd with 9000 miles. This is a water cooled bike. After the bike warms up a bit, when Im sitting still or running slow, the gauge indicates it running hot or towards the hot side of the gauge, but when Im traveling at speed around 55 or 4000 rpms, the temp shows more to the center or normal. Ive checked the water level and it looks like its at the right level, however I do check when the engine is cold. Any ideals? Thanks, Mike  

Answer
Hi Mike,

Cooling systems are designed to be air-free. When we change the coolant or perform other related repairs, air enters the cooling system. Air in the system lowers the boiling point of coolant. If air settles at the water pump, coolant will not flow and serious engine damage may occur.

Example: instead of boiling at 245 degrees, coolant boils at 220 degrees F. Similar to the effect salt has when added to water; lowers boiling point and raises freezing point.

The remedy is to purge the cooling system of air. This requires a limited use tool. I use MityVac's AirEvac purging tool. See the tool here:

www.jcwhitney.com/autoparts/ProductDisplay/s-10101/p-6317/c-10101

The AirEvac tool can be found on-line at $89. You have to perform a search to find the lower prices. Other brands are available.

You can try and burp the system by idling the engine to operating temps with the radiator cap off. This may not work well.

See troubleshooting information below.

Respectfully,
Mark Shively


Overheating:

Primary cause:
Air in cooling system

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug incorrect
IC ignitor trouble

Fuel/air mixture incorrect:
Main jet clogged or wrong size
Fuel level in carburetor float chamber too low
Carburetor holder loose
Air cleaner clogged, poorly sealed, or missing
Surge tank duct poorly sealed

Compression high:
Carbon built up in combustion chamber

Engine load faulty:
Clutch slipping
Engine oil level too high
Engine oil viscosity too high
Drive train trouble
Final gear case oil viscosity too high
Brake dragging

Lubrication inadequate:
Engine oil level too low
Engine oil poor quality or incorrect

Gauge incorrect:
Water temperature gauge broken
Water temperature sensor broken

Coolant incorrect:
Coolant level too low
Coolant deteriorated

Cooling system component incorrect:
Radiator clogged
Thermostat trouble
Radiator cap trouble
Thermostatic fan switch trouble
Fan relay trouble
Fan motor broken
Fan blade damage
Water pump not turning
Water pump impeller damaged