KTM 250 EXC RACING - Manual (Page 42)

ENGLISH
41
Cooling system
Coolant is circulated by a water pump 1 located in the engine. When the
engine is cold the coolant only circulates through the cylinder and the cylin-
der head. After the engine has reached its operating temperature (about
70°C, 158°F), the thermostat
2 opens and the coolant is also pumped
through both aluminum radiators.
Air blowing in through the radiators cools the coolant. The slower the speed
of the motorcycle, the less the coolant is cooled down. Dirty
radiators also reduce the cooling efficiency.
Pressure induced by heating of the coolant in the system is controlled by a
valve in the radiator cap
3 ; a water temperature rising up to 120° C
(248° F) is admissible, without fear of problems.
ƽ WARNING ƽ
– I F POSSIBLE , ALWAYS CHECK LEVEL OF COOLING LIQUID WHEN THE ENGINE IS COLD .
I F YOU HAVE TO OPEN THE RADIATOR CAP
3
WHEN THE ENGINE IS HOT , USE A RAG
TO COVER THE CAP AND OPEN SLOWLY TO RELEASE PRESSURE . C AUTION - SCALDING
HAZARD .
– D O NOT DETACH ANY RADIATOR HOSES WHILE THE ENGINE IS HOT . T HE ESCAPING
HOT COOLANT AND THE STEAM MAY CAUSE SERIOUS BURNS .
– I N CASE YOU GET BURNT , HOLD THE AFFECTED PART OF YOUR BODY UNDER RUNNING
COLD WATER RIGHT AWAY .
– C OOLANT IS TOXIC . K EEP THE COOLANT OUT OF THE REACH OF CHILDREN .
– I N CASE COOLANT IS INGESTED , CONSULT A DOCTOR IMMEDIATELY .
– I F COOLANT GETS INTO YOUR EYES , RINSE THEM OUT WITH WATER IMMEDIATELY
AND CONSULT DOCTOR .
A mixture of 40% antifreeze liquid and 60% water is used as coolant.
However, the antifreeze protection must be at least -25° C (-13° F). This
mixture offers antifreeze protection but also good corrosion protection and
should therefore not be replaced by pure water.
! CAUTION !
– I F THE COOLANT HAS BEEN DRAINED , IT WILL BE ABSOLUTELY NECESSARY TO BLEED
THE COOLING SYSTEM DURING FILLING ( SEE BELOW ).
– F OR THE COOLING SYSTEM , USE ONLY HIGH - GRADE ANTIFREEZE ( E . G . S HELL
A DVANCE C OOLANT ). U SING LOWER - GRADE ANTIFREEZE AGENTS CAN CAUSE
CORROSION AND COOLANT FOAMING .
– E XTREME CLIMATE CONDITIONS OR STOP AND GO T RAFFIC MAY CAUSE OVERHEATING
PROBLEMS . T O AVOID THIS , AN ELECTRIC BLOWER
4
IS OFFERED FOR MODELS WITH
ELECTRIC STARTERS ( ASK YOUR KTM D EALER )
Checking the coolant level
The coolant should be 10 mm (0.4 in) above the radiator fins when the
engine is cold (see diagram). In the event of the coolant being drained,
always fill and bleed the system.
! CAUTION !
I F THE COOLANT HAS BEEN DRAINED , IT WILL BE ABSOLUTELY NECESSARY TO BLEED THE
COOLING SYSTEM DURING FILLING ( SEE BELOW ).
Bleeding the cooling system
By removing the screw 5 at the front end of the cylinder you can drain the
coolant.
To bleed the cooling system, fill in approx. 0.8 liters (0.2 US gallons) of
coolant and remove the bleeder screw
6 . Do not reinstall the bleeder screw
until coolant escapes at the bore without any bubbles.
Then, fill in the coolant until it reaches a level about 10mm above the
radiator fins.
After a short ride, check the coolant level once more.
5
when engine is cold
10 mm
3
6
4
1
2