YZ4A Thermo-Bob Kit


Fits the Yamaha 2010-2013 YZ450F.


Add Spare Thermostat * 

The Thermostat is the only consumable in the system, some people get one now for the future.


The YZ450F has no  factory thermostatic control, so coolant temps can vary widely. As a result, the EFI system overfuels, because it thinks the bike is constantly in ‘warm-up’ mode.  The Thermo-Bob 3 is a machined aluminum housing with a 180°F (82°C) thermostat inside, and modifies your cooling system to operate like automotive systems have for decades… keeping coolant flowing all the time through the engine, but not through the radiators until it is up to a selected temperature.

There is also a threaded port in the Thermo-Bob 3 that will accept aftermarket temperature gauges such as the KOSO or TRAIL TECH 1/8-28 BSPP temperature sending units.
The Installation Manual can be found here.

A full technical write-up when used on a Kawasaki KLR650 can be found here.


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