Don't Fear Changing the ST1100 Thermostat!

[RobbieAG]

What is the reasoning that higher radiator coolant temps equal better fuel mileage? There is a manual choke on the 1100 and I turn mine completely off as soon as the bike will run without it. Maybe 1 to 2 tenths of a mile. I'd rather run cooler temps under the plastic to make rubber hoses and such last longer. Heat is the enemy. If you leave the choke on too long, sure you'll waste fuel, but don't expect you need that choke to warm the coolant faster. A leaner mixture will warm an engine quicker than a rich one. As soon as the engine responds to the throttle without stumbling or quitting at idle, no more choke is needed.

Internal combustion engines run most efficiently when at full operating temerature. The thermostat allows it to reach operating temerature as quickly as possible. Without the thermostat, it will take longer and may never reach it.

 

[Oldbikefixr]

Internal combustion engines run most efficiently when at full operating temerature. The thermostat allows it to reach operating temerature as quickly as possible. Without the thermostat, it will take longer and may never reach it.

+1. An air cooled engine may never reach optimum temperature during cold weather. Fuel efficiency, power, emissions are optimal at that operating temperature. That's why it is easier to get a water cooled engine to keep the EPA happy. A well maintained water cooler is more consistent over a large range of operating conditions than the air cooled variety.

 

[Jim Van]

The temperature of your oil will be far higher than the temperature of your coolant, so there is NO problem with "lubricity". A higher than engineered temp spec for the coolant though may lead to a higher than desired oil temperature. This is one for the "if it ain't broke, don't fix it" book.

Darn !! Now I will need to install an oil temp gauge to find out exactly what oil temp I will have after I install the 190 degree thermostat. I bet the oil temp will be closer to 230 degrees than it was before I install the 190 degree thermostat.

 

[craigstys]

Seven years later I get to bump this thread I originally posted to. Sold my 1991 2 years ago and wanted to replace my regretful sale. Just got a nice 1999 ST 1100 last weekend. And sure enough, it's cold blooded. My guess is this is the original t-stat. Advance Auto Parts still has them at 7 bucks. Here we go again!

Edit: It goes way smoother the second time around and with a cold engine. Done already!