Background:
A somewhat common issue with the ST1300 is a stuck thermostat.
Symptoms:
The temperature gauge on the ST1300 should warm up to 3 bars and stay
there under most circumstances.
The thermostat always sticks in the open state which is good because it
should never cause an overheating situation.
The symptoms of a stuck thermostat are most noticeable when the
ambient temperature is at or below 50 degrees. When the thermostat is
stuck open, the bike may still warm up to 3 bars while not moving however,
as soon as the combination of the ambient temperature and forward motion
continues to cool the bike, the gauge will drop to below 3 bars. It's not
uncommon for no bars to show on the gauge.
Many also report a dramatic decrease in gas mileage during this period.
Causes:
There have been 3 possible causes stated on this site but nothing official
has ever been proven.
us or post in the suggestions thread.)
A somewhat common issue with the ST1300 is a stuck thermostat.
Symptoms:
The temperature gauge on the ST1300 should warm up to 3 bars and stay
there under most circumstances.
The thermostat always sticks in the open state which is good because it
should never cause an overheating situation.
The symptoms of a stuck thermostat are most noticeable when the
ambient temperature is at or below 50 degrees. When the thermostat is
stuck open, the bike may still warm up to 3 bars while not moving however,
as soon as the combination of the ambient temperature and forward motion
continues to cool the bike, the gauge will drop to below 3 bars. It's not
uncommon for no bars to show on the gauge.
Many also report a dramatic decrease in gas mileage during this period.
Causes:
There have been 3 possible causes stated on this site but nothing official
has ever been proven.
- Coolant Quality - Some have noted the coolant used in the bike
during setup may not be high enough quality. - OEM Thermostat Quality - Some have stated the OEM thermostat
did not appear to be a high quality product.
Here is a pic of an OEM thermostat in the stuck open state:
- Manufacturing Process - Many have noticed paint over spray in
areas where coolant exposure and heat cycles would break down the
over spray and allow them to circulate throughout the system -
collecting on the thermostat itself - many have noted corrosion and
buildup on the thermostat which supports this theory.
Here is a pic of some paint over spray from the manufacturing
process as well as a pic of some of that over spray that has
collected in the coolant bottle:
- Over spray removal - checking metallic-to-rubber radiator hose
connections for any paint and over spray and removing it is the first
part to this solution. The use of Scotchbrite for over spray removal
and cleaning the overflow bottle are keys to this step. - Complete flush - Flushing the system thoroughly with water should
help remove any contaminants which did not come out during the
draining of the coolant. - Thermostat and Coolant replacement - Some have used the OEM
thermostat and some an aftermarket one, some have used the Honda
50/50 coolant mix and some have used other brands. Both of these
approaches appear to work. - O-Ring Replacement - When replacing a thermostat, be sure to
replace the o-ring along with it. Some aftermarket thermostats come
with a new o-ring, but the diamater may be smaller than OEM. Given
how inexpensive an OEM o-ring is, replacing with a new one is cheap
insurance.
us or post in the suggestions thread.)
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