Hello, i am from france and i have an early cbr1000 and i have a problem. The fuel systems leaks like a sieve. I have replaced the the float and needle and float bowl o rings. I have replaced the fuel lines that had split under pressure from the fuel pump as they were old. I tested for leaks from the carbs on the bench by gravity with a remote tank...all good with float heights set at 9.5 mm. When it goes on the the bike with the fuel pump running with the bike, the 2 left hand carbs start to leak. I'm running out of ideas. Maybe fitting a fuel tap that gravity feeds the carbs? The problem i have with this is finding a fuel tap with a vacuum fitting that will have the same thread fitting as the original, as the alternative tap in the honda parts micro fiesche looks to be a different fitting. Old cbr900 blade looks similar but i cant tell exactly what size its mounting threads are.
Any advice would be greatly appreciated
kind regards Hug

https://fr.fowlersparts.co.uk/parts/...f-yb/fuel-tank

 

the fuel pump on the CBR1000 is not high-pressure, are you sure the correct one is installed? It sounds like it's overwhelming the float valves.
You don't really need the vacuum shutoff on the fuel tap - that's really just incase you forget to turn the tap off when you stop the bike.

 

Hi, thanks for the reply. My thoughts also were that the pump was pushing the float valves open, but it looks to be standard. With the standard block connector connection. One of the reasons i was asking about a vacuum tap was that original tap is in a bit of a sorry state. Im going to pull the tap apart and maybe try rigging it direct to the carbs.

 

How did you get on with this problem?
I've also had a similar issue with mine. I also have rebuilt the carbs and set the floats but it still floods now and again. I have a 1978 H-J and doesn't have vacuum shut-off.