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Switching off fuel tank when parking

Discussion in 'Bling and Appearance' started by norm79, Aug 29, 2006.

  1. In the owner's manual, it says the fuel tank shall be switched off when parking your bike for longer than a few hours, to prevent fuel running into the Cab. I follow the rule so far but occationally forget to turn it on when riding. It had not caused too much trouble until today. I did not warm up the bike. There was a traffic light in Red about 50 meters from where I parked. So I line-filtered to the front. Just when the light turned green the bike stopped. It took me a few tries before realising that was the fule switch I forgot to turn on. I felt quite embarrassing althrough the drivers behind me did not make a sound on it.

    Does anyone know any technical reasons why we need to turn off fuel when parking? What problems we will be facing if we leave it on at all time? Thanks.
  2. I leave mine on.

    Never had a problem.
  3. Neve done it in my life and it's never made a scrap of difference.

    It's 'nanny-state' guff from the manufacturers, nothing more....
  4. I really wouldn't bother about turning the fuel valve off. If your leaving the bike parked for a month or more, then yes I would.
  5. Ditto, a least since the vacuum tap was invented in the 70s.......
  6. If you're worried about your bike sitting so long the fuel goes stale - you should be draining the tank.
  7. the main practial reason is that in the carby construction there is an internal fuel resovoir (the float bowl) that has the fuel flow into it metered by a "needle" that is tapered precisely to fit into a chamfered hole through which the fuel runs to fill the float bowl. if a piece of grit/rust ends up there, or there is a leak in the float (which controls valve position) then the needle is kept open slightly ausing the bowl to overfill. this overflow runs into an overflow tube in the carby which drains underneith the bike. a fuel leak here will lead to a fire/slipping.environmental hazard as immediate as space of a few minutes...

    Long story short, shit in the carby = bike pissing fuel.

    If the overflow pipe happens to be blocked, expect a hydraulically locked piston.... = big bucks. (But extremely unlikely.... unless you went out of your way to jam the overflow pipe with mud/kink the overflow pipe.
  8. If you were to run a poll on how many riders turn off the fuel tap, I think you will find a very small number who do...
  9. Well, sorry to say but I am one of those few people who switches the fuel tap off. At least I was on my old 250. I guess I just got into the habit I am sure it doesn't make any difference. However, my mate is someone who never turned his fuel off, so if he ever borrowed my bike 9 out ten times he would forget to switch it on and the bike would cut out about 5 mins into the journey it was fun to watch the first time it happened.
  10. It would slow down a thief i spose.....
  11. The smaller the amount of fuel, the quicker it will go off.....

    I.E A bike tank will foul quicker than a car tank which will foul much quicker than a pertrol tank in the ground at the station.

    The fuel in the float bowls is VERY small amount and will foul quickly.

    I suppose in winter this could mean harder starting, but generally not a problem if left less than 2 weeks....

    A month and you might find it would turn to gum and block your carbs.

    I dont bother.
  12. I wouldn't worry about too much if your not riding your bike for a short amount of time. My bike doesn't even have a off position on fuel tap. If i'm not going to be on it for over a month i'll drain the tank, carby bowls and put it on a slow trickle charge.

  13. On most modern bikes it’s probably not an issue, but buggered if I know what different bike specs are.
    But I know that if you’ve got a bike with gravity feed (no fuel pump) Its essential to switch the fuel tap to off because if its left on after the engine is shut down there is the possibility that fuel can leak past the needle and seat of your carbie and it will overflow in the float bowl which will make its way into the cylinder and wash the walls and dilute the oil, this offcourse is bad.
    I always shutdown my bike via the kill switch first, then turn ignition off, and then turn off the fuel tap.
  14. Mebbe so but I have no choice but to turn them off on the Grumpy Trumpy - unless I want fuel spilling onto the ground - can't afford that - literally :)
  15. No, that is often incorrect. Virtually all bikes built since the mid 70s (except some old poms), have a vacuum fuel tap. Many people confuse the 'prime' position of a vacuum tap with 'off'. A vacuum tap contains a diaphragm that defaults to turning the fuel off, ie no fuel can get from the tank to the carby at all. When you start the bike the fuel in the carb bowl allows it to fire, and as soon as it does the vacuum hose connected to the fuel tap turns it on, when you shut down the engine it automatically turns off. In the unlikely event that that there is no fuel in the carby, the tap can be moved to the 'prime' position which bypasses the diaphragm, as soon as she fires it should be turned back.
  16. Interesting, but why do you fell the need to use the emergency switch and not just the key to turn off your engine? :?
  17. Scooter I hit the kill switch to shutdown always, Its one thumb action and its fast.
    Also in the event of some type of weird arse emergency whilst riding, I wont be looking for the kill switch as its an ingrained habit now.

    I just took a squiz at my H-D manual, it says –
    ‘Always close the fuel supply valve when the engine is not running. This prevents flooding of the carburettor and the surrounding are with gasoline.’
  18. fair enough, the reason tha I asked was that it was suggested when I had the triumph, using any one of the three kill switches could throw out the electronics, so I got out of the habit of using it with that bike.

    Kill switch/sidestand kill switch/clutch in gear kill switch.
  19. Well, sort of. It is NOT essential to turn the fuel tap off. Never done it, never had a problem. Secondly, I have a 1980 Bol D'or, and it doesn't have the vacuum switch fitted, and like I said, I've never had any overflow problems this was supposed to eliminate. They did fit them to later and US versions, but most people by-pass them because they're more trouble than they're worth. I guess this is a classic YMMV situation, but for me, it stays on.

  20. I've 'killed' my kill switch (handlebar) for that reason - cut the wires off - it's just a decoration now :grin: