Thermo-Bob 1™ Installation Manual: 1986

Thermo-Bob 1™ Installation Manual: 1986-2006 Kawasaki Concours
This is a basic guide for installing the Thermo-Bob 1™ on a Kawasaki ZG-1000 Concours. The bike used in the
following photos was a 1995 year model (US Version).
Proper installation is critical: if you are not familiar with or feel uncomfortable with heated, pressurized liquid cooling
systems, you should have a professional install the kit. Improper installation can cause engine overheating and
possible engine damage.
Read through these instructions completely to familiarize yourself with the hardware names and installation
procedure. This will also allow the bike to cool off if ridden recently.
Figure 1 below explains the basic location of the two key pieces of the Thermo-Bob 1™ radiator bypass system. This
modification changes your cooling system to be like every automobile engine has been for the last 70 years: rather
than have the coolant entering your engine being cold from a trip through the radiator whether it needed to go there
or not, the Thermo-Bob 1 allows coolant to bypass the radiator, maintaining a constant 185° F inlet temperature and a 195° F outlet temperature. With the stock Kawasaki setup, coolant entering the engine varies from 40°F to
185°F, and large temperature gradients across the engine are not desired to maintain internal tolerances.
Figure 2 shows a modified parts diagram of the stock cooling system with colored lines representing coolant flow. In
Figure 2, red is hot water exiting the engine and travelling to the factory radiator, blue is the cooled water coming
from the radiator to the coolant pump inlet, and green is the same cooled water slightly pressurized by the pump,
flowing from the coolant pump exit into the engine block.
Figure 1. General view of cooling system and location of Thermo-Bob 1™ and TEE fitting.
Figure 2: Factory Cooling system components and coolant flow paths. The Thermo-Bob 1 will be installed up at the
top of the diagram in hose 39062D, and the bypass TEE will fit on the cold side of the radiator between hose 39062E
and tube 32102. Even with the thermostat in the Thermo-Bob 1 closed, coolant can continue flowing through the
engine and directly back into the coolant pump for quicker warm-up and minimized temperature gradients across the
engine... just like every car for the last 70 years.
STEP 1 - AREA PREPARATION
It is not necessary to remove the upper fairing for this installation, although it is easier with the right inner piece of
the fairing (dash-pocket) removed. It will be easier to begin with the fuel tank almost empty to make it lighter and
easier to handle.
Both left and right side fairing lowers should be removed and set aside, as well as the inner plastic pieces on the left
side of the bike (the radiator duct shown in Figure 4 and the heat guard plate). To help visualize the final product,
Figures 3 and 4 show a completed installation of the Thermo-Bob 1.
Figure 3. Final Installation Location of Thermo-Bob 1™ in upper hose (colored red), headed to radiator. Bypass
shown is highlighted in gold.
Figure 4: Left radiator shroud near left front of engine that needs to be removed for kit installation. This photo is
actually of a completed installation: note the Thermo-Bob 1’s bypass hose is highlighted in gold for reference.
Figure 5: The Thermo-Bob 1 bypass tee fitting will be installed at the lower end of this 90 degree bent hose which
has been highlighted in blue: this is the radiator exit and coolant heads down through the metal coolant transfer line
to the inlet of the coolant pump. Note that in Figures 5 and 6, the factory coolant hoses run in close proximity to the
exhaust headers. Pay careful attention, as you install the new bypass tee fitting and by pass line for the Thermo-Bob
1, you must be sure of adequate clearance of all components.
Figure 6: Other end of metal coolant transfer line has a rubber hose section that connects it to the coolant pump
inlet. The coolant pump is just visible on the right.
Your engine should be cool to proceed.
STEP 2 - DRAIN THE COOLANT
You will need a catch pan for coolant to drain into. Underneath the engine, you will see a second metal coolant
transfer line which is on the outlet of the coolant pump. In that line you’ll find a drain bolt and sealing washer shown
in Figure 7. You can also find them in Figure 2 as part numbers 92151 and 92202A. Remove this bolt, then remove
the radiator cap – which is easily accessible just behind the steering head area on the right side. Removing the cap
allows air into the system and the coolant will drain rapidly. Allow the coolant to drain.
Figure 7: The coolant drain bolt is on the bottom of the metal line shown. This photo was shot on the floor of the
garage, looking up on the bottom of the engine.
STEP 3 - BYPASS TEE INSTALLATION
After the coolant has drained, clean and reinstall the drain bolt, reusing the factory sealing washer. Torque to
Kawasaki specification (55 INCH-pounds which is less than 6 foot-pounds!). Remove the lower radiator (elbow)
outlet hose shown in blue in Figure 5, and the metal coolant transfer tube, part # 32102 in Figure 2. As stated before,
this line connects the radiator exit to the coolant pump inlet with a short rubber line on each end (see Figures 5 and
6). Again, note the close proximity to the exhaust system in this area, and how the lines are routed as original from
Kawasaki. (Note the factory supplied zip-tie, part # 92072A in Figure 2.) You need to make room for installing the
Thermo-Bob 1’s aluminum TEE and brass fitting for bypass line as shown in Figure 8. To make some room in the line,
shorten the metal coolant transfer tube. Originally, this metal line has two hose barbs on each end. Use a hacksaw to
shorten the line, only leaving one barb on each end. After making both cuts, carefully remove all burrs from the ends
with a round file or rotary stone. Carefully wash out the line, removing all traces of metal chips from o.d and i.d.
Next, remove approx. 1/4” from the bottom end of the blue hose in Figure 5. Install the aluminum TEE fitting from
your Thermo-Bob 1 kit with brass 90 Deg. fitting pointing up as pictured in Figure 8. Install the supplied short length
of 1” i.d. coolant hose between the bypass tee fitting, and the shortened metal coolant transfer tube, (part # 32102
in Figure 2) as shown in Figure 8. It is important to make sure nothing is in contact with the exhaust headers.
Figure 8: Completed bypass tee installation. Factory radiator exit hose is shown as blue, short extention hose is
shown as green, supplied bypass hose is shown as gold.
STEP 4 - REMOVAL OF FACTORY THERMOSTAT
With the fuel tank removed, the original equipment thermostat housing is easily accessible, see Figure 9. Remove
the 3 bolts holding the thermostat housing top, and remove the original thermostat. Remove any debris, sediment
etc. from the housing; check the condition of the o-ring held in the cap. If you need a new o-ring from Kawasaki, this
is the time to replace it. Most likely it is fine if it wasn’t leaking, so you can reinstall the o-ring, cap and retighten the
bolts to the housing to Kawasaki specification (55 INCH-pounds).
Figure 9. Location of original thermostat housing.
STEP 5 - THERMO-BOB 1 INSTALLATION
The upper radiator hose is easily accessed while the fuel tank is removed. Hold the new Thermo-Bob 1 housing in
position, see Figure 10. You want to cut out enough hose to allow installation of the Thermo-Bob 1 housing:
removing about 2 1/8” (2.125 inch) works well. Cut carefully, this is easily accomplished without removing the hose
from the metal filler-neck or the upper radiator outlet. Install the Thermo-Bob 1 with its brass 90 deg fitting pointing
back toward the engine as shown. Leave the clamps loose for now. Also, imperative that the Thermo-Bob 1 is
oriented correctly, meaning the bolts in the housing must point toward the engine as shown. (If the Thermo-Bob 1 is
installed backwards, the engine will overheat, with possible engine damage.) The Thermo-Bob 1 will need to be
rotated downward, in effect allowing some extra clearance for the brass fitting/and bypass line to avoid contacting
the leading/lower edge of the fuel tank. You may want to set the tank back into its position to check for clearance.
Make sure the large rubber grommets are in place for the fuel tank to sit in its proper position, see Figure 10.
Figure 10. Thermo-Bob 1™ location when installed.
After this trial clearance check, remove the fuel tank and tighten the two large hose clamps on the Thermo-Bob 1.
STEP 6 - BYPASS HOSE INSTALLATION
Now you can install the bypass hose between the brass 90 degree fittings (one is in the Thermo-Bob 1, the other is in
the TEE fitting that you installed in Step 3. On the installation shown, this required 28.5 inches of 3/8” hose – your kit
includes a 31 inch section. There are a few different paths that can be used: the one shown in this manual followed
the routing that appeared to give the least possible damage to the bypass hose. Reference Figures 3, 4 and 8
through 13. The bypass line runs just below the metal filler neck, thru the upper frame member, proceeding across
and above the front of the valve cover. Use zip ties to support the hose, careful to avoid pinching or allowing the
hose to rub on any sharp edges etc. The hose is not resting on the valve cover, but suspended beneath the frame
tubes.
Figure 11. Screwdriver and red arrows point at bypass hose routing. The Thermo-Bob 1™ is just out of sight on the
right side of the photo.
Figure 12. Bypass hose routing on left side of bike. Note ‘mousebite’ that has been trimmed out of the left radiator
duct (you’ll do this in Step 7).
Figure 13. Overview of bypass line routing.
STEP 7 - INSPECT FIT AND CLEARANCES
It will be necessary to slightly trim left radiator shroud to clear the bypass line. See Figures 12 and 14.
Check bypass hose routing, making sure plenty of clearance exists, especially in exhaust header area. Verify that all
clamps are tight: you have added 6 clamps to the system (two large and one small on the Thermo-Bob 1, and two
large and one small on the TEE fitting. Don’t forget to check the factory clamps that you removed on the bottom of
the coolant transfer pipe (part 32102 in Figure 2: it was modified in Step 3). As a clearance check, reinstall the left
radiator shroud shown in Figure 14, making sure the notch you made clears the bypass line. The shroud should install
just as easily as it did before you installed the Thermo-Bob 1. Now that you know it fits back as good as original, set it
aside for now.
Figure 14. Mouse bite trimmed out of left radiator shroud.
Double-check all your hose connections, the orientation of the Thermo-Bob 1, and verify there are no interference or
fuel tank issues.
Figure 15. Time to refill the cooling system.
STEP 8 - REFILL THE COOLING SYSTEM
As shown in Figure 15, fill the radiator slowly as to minimize coolant spillage, and use a fresh mix of 50/50 Ethlyene
Glycol and distilled water. At the top of the coolant pump is a vent bolt (see Figure 16) - you could then loosen it
until you see coolant seep out around the threads, as air will purge from the system when you loosen the bolt when
the system has coolant in it. Re-tighten the vent bolt to 55 in-lb (less than 6 ft-lb).
Figure 16. Vent bolt at top of water pump.
Top off the radiator with coolant, then reinstall the radiator cap. Make sure the original wire to the temperature
sending unit is connected; the sending unit is screwed into the rear of the original thermostat housing. This must
remain for your original temp gauge to function as normal, even though the housing no longer holds a thermostat.
See Figure 9.
STEP 9 - CHECK FOR LEAKS
Reinstall the fuel tank and connect the fuel line and the vacuum line to the petcock. Start the engine and let it idle
for 2 minutes, then shut off the engine. Remove the fuel tank and inspect the cooling system hoses near the
Thermo-Bob 1 and bypass TEE for any leaks.
Check the left side carefully in the header area close to the new TEE fitting etc. You should have at least as much
clearance between all components and the exhaust headers as the original plumbing did. It is now time to reinstall
the left radiator shroud (Figure 4).
Let the engine cool down, remove the radiator cap carefully, add coolant if necessary.
STEP 10 - FINAL COMMENTS
It is incumbent upon the installer of the Thermo-Bob 1 kit to verify proper orientation of the new thermostat
housing, and correct coolant line connections etc. Although this installation is not extremely difficult, good
workmanship on the part of the installer is important to prevent possible engine damage or personal injury.
It is recommend that after a short test ride, take the time to go back and inspect your work, remove the fuel tank and
left radiator shroud to make sure of no leaks, no hoses touching the exhaust headers, no interference between the
Thermo-Bob 1 housing and the tank etc.
Figure 17. Completed installation: note Thermo-Bob 1 in place with fuel tank installed.
Now your Concours should enjoy a much more stabilized cooling system. You will notice the temp needle remains
much more stable at cruising speeds, and will not drop back to the cold mark when riding on cool days. The needle
will fluctuate very slightly as the fan cycles on and off.
REPLACEMENT PARTS
(Recommended replacement frequency: every 5 years or 40,000 miles, whichever comes first)
You can purchase replacement thermostats and o-rings at www.watt-man.com.
If you have a local NAPA auto parts, the 195°F thermostat is sold as NAPA part number 266. They also sell a 180°F
thermostat as NAPA part number 166.
If you have a local STANT dealer such as Pep Boys, they typically sell the 195°F thermostat as part number 29829
(they sometimes call this 13829), and the 180°F version as part number 29828 (sometimes called 13828).
There are also "Heavy Duty" thermostats which for this forward-flowing design are unrequired. Nonetheless, the
"29" first two digits would change to "59" and the "13" first two digits would change to "45" as shown on the next
page.
Unless special ordered, your
Thermo-Bob 1 was shipped with a
STANT 29829 which is a 195°F
thermostat. Do not try to crossreference the part number to a
different brand, they typically will
not fit properly.
Again, if you are unable to find
parts locally, replacement
thermostats (as well as the skinny
o-ring in the Thermo-Bob 1
housing) are available at
www.watt-man.com.
IM TB1C V1
www.watt-man.com
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