RVF400 Fuel Tap

[fay]

Hi

Does anyone have picture of a RVF400 HRC fuel tap. Not sure if mines is HRC or not.

[Neosophist]

I suppose somebody has to answer this.

There is no such thing as an HRC fuel tap.

There is however a modification you can do to the fuel tap to disable the vacuum diaphram that shuts off the fuel flow regardless of tap position when the engine isn't running. This is known as the HRC fuel tap mod as it was advised to do this when fitting the HRC supplied race kit to the bike.

The reason to disable this safety feature is that with the larger jets and open carb set-up of the HRC race kit the fuel consumption is increased a lot and the diaphram does slow the fuel flow down a little, so at prolonged periods of wide open throttle, such as racing down a long straight the bike can use all the fuel in the carbs before they have chance to fill back up.

On a standard road bike this mod is not recommended. If the bike is crashed or dropped over with the fuel tap on fuel will flow indefinatly until the tank is empty causing a big fire hazard.

If the carb float needles fail to seal fuel will flow into the engine and can ruin it if you try to start it, either hyrdaulic lock and bend the con-rods or ruin bearings becuase of diulted oil.

But either modded or not, you cant tell be looking.

If you disconnect the fuel hose and turn the tap on, if you have a lot of fuel flow then you have a modded tap.

If you have a slight drip then you have a leaking tap / worn diaphram.

If you have no fuel flow at all then you have a stock tap.

[fay]

Thanks for the info Neosophists.
I just had new spark plugs put in the bike started for two days and now it wont it sounds flooded to me and I was advised to turn the fuel tap off and try to start then to put it back on. I tried this and it still wont start maybe I will try to kick start it but not sure what else could be wrong.Really frustrating..
it sometimes backfires but the engine wont take

[speedy231278]

Some plugs get fouled very easily if you try and start the bike repeatedly and it doesn't fire up - even brand new ones. You may need to have the plugs out and clean them up. People apparently do this by using a gas flame to burn all the crap off. I've never had to do this. A few tips - if the bike doesn't start first time, leave it a few minutes before trying again. Also, don't stop the bike almost immediately after starting. Let it warm up a little first. The plugs seem very prone to issues with starting, it might possibly be down to their very small size. Also, most people recommend starting with the choke fully out and using absolutely zero throttle. In my case, I find just the tiniest whiff of throttle when the starter is turning is often necessary. I suspect it depends on the bike. However, too much fuel immediately on starting seems to overwhelm the plugs, so be very careful.

[Neosophist]

Hmm.

More info.. new bike, old bike, any other problems?

Plugs are easy to destroy, and often you will need another new set!

Most common reasons for not starting.

1. bad techique (full choke and no throttle until ticking over, then reduce the choke as soon as possible and warm up with throttle)

2. dead / weak battery (often neglected and easily damaged.. a poor battery wont start the bike)

[fay]

Thanks for the updates

Its old bike sat for over a year, choke does not work at all seems to be rusted and stuck.
We put on new plugs cleaned the carbs butterfly was stuck new oil new battery and it started fine used it for two days then started it again on the fifth day and switched it off and on the 7th refused to start.
I hope the spark plugs are ok because they are expensive seems like I will have to get the choke sorted out.

Can you advise if its necessary to switch the kill switch off when not riding or can I just always leave this on run.
Sorry for silly questions but this is my first bike and still learning.