you can't always go by that. that's why these test kits were invented. I had to often use these at the dealership I worked at. because the leak could be very small. and the factories required us to show them the proof before warranty claims were accepted.
Agree , but it's a good place to start, and is free. If he's got bubbles straight away, that's a really good indicator . Just went through all this 2 race weekends ago with a fresh motor that had no issues for years prior to the rebuild (was a spare motor i used periodically).
I know that you replaced the rad cap, but how is the cap sealing surface? We had our endurance bike overheat or run really hot until we checked the cap flange and saw that is was lightly bent. Fixed it, and gained like 2 HP. Which is incredible on a 1992 CBR600 F2! Or increase the bar on the rad cap, which can help keep engines in their zone.
New cap, new radiator, checked all connections. It's not the head gasket either. I'm almost certain I have an air bubble in the system. Bike is running around 220 which is 30 degrees higher than normal. If I take bike for short ride, temp will rise to 220. Then the temp will drop quickly down to 190! I'm thinking the air found its way out. But then it will go back up to 220! Bring bike back in and let it cool down. Water level dropped. Refill and run again for a few minutes. Same thing! How the F*** do I get this air out?
Its almost impossible to screw up filling the coolant system of an 06-current r6. The rad cap is the highest point. Its not like a gsxr that has a burp screw on the back of the head. Put coolant in, run for a sec.. put a little more in.. done. Something else is goin on. And guessing you still have not checked for bubbles with the rad cap off?? Said it before. Free test, easy to do, can almost be assured its a head gasket issue if you see bubbles.
You're so sure it's not the head gasket but still haven't verified it? Get a block test kit from a parts store, lower the coolant in the radiator a good bit, and run the bike with the test fluid in the tube and see if any air comes through the air stone. This may take a little bit to build some air pressure in the radiator. Obviously you don't want coolant getting pushed into the tube through the stone, keep that in mind, that and you don't want to scald yourself. Weird symptoms, loosing coolant, acting like air in the system, definitely signs you may have a head gasket on it's way out if you're verifying everything else in the system. It's not like the cooling system is a difficult thing.
It's way easier to use the test kit I linked to that turns colors if combustion gasses are in it. That's what the factories required me to do for warranty claims
Put a head gasket on it so it stops pushing combustion gasses into the coolant. That is how you get that air out.
