Thermo-Bob 3 for WR450F: 03-15, YZ450F 03-09
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This kit fits the Yamaha WR450F from 2003 to 2015, and also fits the Yamaha YZ450F from 2003 to 2009.  Please see other products for the version that fits other motorcycles.

The WR and YZ450F are popular choices as snow bikes, and in those applications, the lack of factory cooling system control leads to cold coolant temps.  The carbureted bikes then have inconsistent jetting, and the EFI bikes end out overfueling, thinking 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.

  • Item #: TB3-WR4

Thermo-Bob 3 for WR450F: 03-15, YZ450F 03-09

Price: $129.00
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