Join Date: May 2004
Location: Toronto, Canada
+1 on the air pockets deal. When you refill the cooling system at the radiator cap, get as much air out as possible, then run the engine for a few seconds, then refill it again. If the level is up to the bottom of the little housing where the radiator cap sits after the engine has run and then cooled down, this is not the problem.
Before going after the really expensive stuff, make sure the coolant temperature sensor is within specifications. The engine could be fine, but displaying higher than the real temperature.
Next thing to check is the actual operating temperature of the thermostat to make sure *that* is within specifications. And make sure the little vent hole isn't blocked.
Make sure the radiator isn't half blocked with bug guts with the other half of the fins smashed in from rock hits.
Make sure the radiator cap is good. For the price of a new one (you can get the same one at Canadian Tire, many older Honda cars use the same cap) just replace it.
The secondary air injection system won't make a significant difference to how much heat goes into the cooling system.
If the above check out, then it's time to drain the system and inspect the impeller of the water pump, and while you are at it, inspect the insides of the hoses and pipes for debris or blockage.
If the cooling system checks out, then it's possible that you have a lean condition. If you haven't changed anything in the electronics then there could be something going wrong. Clogged fuel injector, low fuel pressure (bad pump? seen that happen - or bad fuel pressure regulator, which is inside the pump assembly), clogged pick-up screen (inside pump assembly), etc.
The possibility of a blown head gasket has to be considered. Usually, this will show up as the reservoir getting full but not sucking the coolant back into the engine when it cools down, and this will get progressively worse. In the early stages, you might not notice this. I've had a few blown head gaskets over the years on various bikes, but it hasn't been reported as a big problem on the ZX10R's.
Helibars, MRA screen, Ohlins damper, reversed shift pattern, sorted suspension, braided lines, Michelin Pilot Power, all else stock 'coz it's fast enough!