46 minutes ago, CandyRedRC46
I am not a fan of the VTR fan blades, they work great while moving at 15mph+, but they are awful while stuck in traffic, because you are just pushing hot header/engine compartment air across your radiator.
Strangely I did the VTR mod & I measured the temps, it does NOT pull hot air, unlike the standard fan which fights normal airflow up to a certain road speed when on, rather than enhancing it. But beware a largish stone flicked into the fan will fold over the inner rad fins, so fit a stone guard. The VTR mod starts cooling at rest, then increases air flow through the rad as road speed builds.
As an aside if the VTR didn't work, then neither would the 4th or 8th gen fans, as at a standstill they suck in air from the same place in front of the engine ! The VFR is one of the few where the rads are above rather than in front of the exhaust pipes, although only 50% of the engine heat comes out the front side, as the rear cylinders vent elsewhere. Also the side mounted rads don't tend to suffer stone hole damage as a few 8th gen owners have reported on this forum. They also make engine maintenance simpler as you can access the front head without removing/moving the rad !
For the OP, check the rubber seal on the rad cap, also check the lips on the rad cap, they should be square like an L if the upright of the L is the side of the cap, the lip underneath should not be bent down ! It does happen through ham fisted use, you should always push down on a rad cap before twisting ! to get past the retension tabs on the rad cap holes rim. Mine was like tahat when I got it, so I bent the lips back & fitted the cap 180 degreess around, by that I mean if you cap read the words on the cap right way up when stood to the right of the bike, remove cap & replace so the words are now upside down !
The rad cap controls the pressure of the fluid in the cooling system, there is a bleed hose below the rim that passes across the engine through the V to the left side mounted expansion tank. When cold the expansion tank should be filled to the LOWEST mark. The fluid in the expansion tank is there to act as a coolant to the expelled fluid/gas that comes from the rad cap pressure release, thus condensing it as it arrives in the tank. At maximum permitted temperature the tank should only reach the high mark, if it keeps rising there is a fault in the cooling system, as in your case.
For everyone else a failed OPEN thermostat plays NO part in the cooling system. On the other hand a failed CLOSED thermostat will cook your engine in double quick time. If you want to check your thermostat as possibly stuck open, start bike & allow to reach 40c+ on the dash or just over 100f for you old worlders :) Put your hand on the top collector of the right rad through the air vent in the fairing, it should be at atmospheric temperature or just over as there is a small bleed hole in the thermostat. Once the temp guage shows 70C+ or 170F it should suddenly get hot as the thermostat opens & swaps the hot coolant for cold coolant from the left rad, after a few cycles the whole system will be at 70C+ then the thermostat will stay open unless the cooling air reduces the whole system to lower than its opening temperature, at which point it will start to close to restrict flow to control engine temp.