I have a race bike with the fuel tap mod and you are still able to turn the fuel off, you just have to do it manually. When in the off position, there is no fuel leakage. The only problem I have is remembering to turn it on!!!

duncan wrote:If fuel is leaking past the carbs into the cylinders then the fact that the tap is off will not make a lot of difference to the outcome because of the volume of fuel available in the wide diameter pipe between tap and carbs

Just run the bike with the tap off for a minute or two when you pull up before switching the engine off to drain some of the fuel..

And that volume of fuel might well just leak past the pistons into the oil... when you run the risk of dumping most of a tank into the cylinder / oil theres a much higher chance it'll happen (as has happened to people in the past)