Thermostat Replacement

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Thermostat Replacement

Postby Gman » Sat Mar 07, 2009 3:09 am

Depending on model of bike.

Make an auxiliary fuel supply.I use an old RedX bottle as it has a nipple on it that takes a small piece of fuel pipe nicely,


WD40/Rust penetrant
Household Scotchbrite/none ferrous abrasive pad or similar.
Carb/Brake cleaner or similar degreaser
Washing bowl to collect coolant.
Funnel or pouring jug.
Silicone gasket sealer(Blue Hylomar or similar from Auto discount store) or Clear silicone Bath/Window sealer.
Bog roll/Toilet roll.
Large flat-blade screwdriver for Jubilee clips or Mole-grips/Vise Grips.
14mm socket or spanner(US ratchet) for Rad coolant Nylon bolt(Note Hardware superstores have longer nylon bolts like
this in the Bathroom/Plumbing section which can be hacksawed down to fit and you can make the rubber washer out of some old inner tube and a punch/drill and a pair of scissors).

10mm socket with extension for for long neck Thermostat bracket/Heat deflector bolts(4 of into the Cylinder head).
8mm spanner or socket for Thermostat housing bolts etc.

1:Remove tank
2Place bowl under Rad.
3:Remove Rad cap
4:Remove 14mm Rad bottom plug bolt.
5::Allow coolant to drain.
6:Pull Temp sender wire and Oil Temp wire(Remember colour codes and which goes where,not hard) from Harness
at Thermostat housing area(If first time wrap a bit of masking tape as a tag around each wire and write Thermo/Oil on the respective bits of tape).
7:Remove four 10mm long neck bolts to allow the Main top bracket to be free.
8:Remove the two 8mm M6 bolts from the top metal coolant pipe knuckles for each side.Do NOT try and pull the knuckles and pipes off straight away.
Better to tap them both whilst spraying the WD40 type stuff on and around them and tap lightly with a small ball pane hammer at the sides or the heavy
end of a Socket wrench or adjustable Spanner.You want to break the,"Seal-of-Age" and not damage the old O-rings any more than age has if possible.
The coolant pipes and the knuckles will need servicing/cleaning hence the Carb Brake cleaner and the tissue/toilet paper and the o-rings will have been flattened by age and if lucky not broken.
If the O-rings are intact but flat you can rejuvenate them by placing them in a pan of water and bringing to boil and then let them cool naturally.They will regain/remember some of their elasticity enough to be re-used along with the,"Silicone Gasket Sealer".

If unserviceable see this

and you can source them from any good plumber's suppliers(Yellow pages).

Once you have the pipes and knuckles off you can dismantle the thermostat housing.There is a large O-ring in there
as well so hope that's ok and if not again local plumbers may be able to help and or the Plumbing section of a local DIY superstore.
If you do have recourse to do this please post part numbers found for other users.

Clean all parts and degrease.Put new thermostat in and reseal using Gasket sealer etc on all parts that you know
require it including when you push the small cooling pipes in and the knuckles and reverse the removal procedure and re-fill with coolant.

Once all done and with the Radiator cap off start bike using Aux fuel supply and run the bike up to operating temperature so that
the thermostat opens and you can see the coolant flow over the fins a few times.When all air is out of the system replace RAD cap but be careful
of heat and burning hands.

Check for leaks once the Radiator cap has been replaced and the system builds some pressure.When happy go for a ride around the block to put some load on the engine and check again.These small checks will pay dividends as these jobs don't have done often so do them right now and you won't have to keep going back to them and the next time you will sail through them :)
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