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Silly question from a Silly person - Fuel Switch

Discussion in 'General Motorcycling Discussion' started by Panthus, Jul 11, 2006.

  1. Okay...now don't laugh when i ask but i seriously don't know!!

    When i bought my little 250 Suzuki Bandit the other week i stood there looking at the fuel switch scratching my head. It has three selections. They are ON, RES and PRI. Okay, I have the On and Res covered but what is this PRI you speak of?

    One of my mates, who also rides shruged his head at it, then proceeded to tell me thats where it needs to be. However, having run out of fuel on Victoria Road today (aw gawd!!) with the switch on that selection, the little voice in my head says no, thats not where it should be. (amongst other incessant natterings it does)

    Any help? Comments? or rude jokes??

    Thanks in advance!!!! :grin:

  2. P lease
    R ead
    I nstructions

    Sorry, no valuable comments.
  3. Primary!

    The idea is that you leave it on Primary.
    This setting takes fuel from a higher point in the tank than Reserve.

    The idea is when you run out of fuel, instead of going,
    "Oh no! I have to push this thing for ages!"

    You go: "Aha! I'll just switch to Reserve and make sure to stop at the next servo. God bless those clever buggers at Suzuki, I must remember to write them a thank-you note."

    Edit: nevermind, I read "OFF" instead of "ON" in the original post. See below for probably more correct answer...
  4. i tend to just leave my fuel switch on the "on" position and switch to reserve when i run out of fuel. that way i got a good couple of kays to reach a servo.

    my suggestion is never ride on reserve, then ur buggered if you run out :p
  5. Okay so i have the acronym down pat now, but im still left with confusion (it really doesn't take much trust me!!)

    We have Primary, On and Reserve..

    Whats the diff between Primary and On?

    Is primary just to test me to make sure im still awake upstairs to flick it to On, then once i have used a bit more then down to Reserve?? Seems like alot of Fuel switch fondeling during my ride.
  6. PRI=Prime.

    I believe it's to prime the carbs if they've run dry? I could be totally wrong, but it makes sense to me. From memory, these fuel taps are the vacuum type and fuel doesn't flow if the engine is stopped. If the bike runs out of fuel you need to get fuel back into the float bowls.

    There is no 'Off' because a vacuum fuel tap does not flow unless there is demand.

    From a Bandit website (Google cache as the source)
    www.banditsrus.com/wwboc/banditfaq.htm+PRI+fuel+tap+bandit&hl=en&gl=au&ct=clnk&cd=1&client=firefox-a]Fast Larry's Bandit FAQ[/url]
  7. okay, that kinda makes sense because when i googled i got this:

    PRI" is used to refill the carburetor float bowls only after rebuilding the carburetors or after carburetors have been drained of gasoline for strorage

    So i really shouldn't be riding with this selection should i??
  8. Prize goes to cejay! :dance:
    Yes, it is short for prime and it lets fuel run into the carbys when the line dries up. Don't leave it there to run the bike, that's what "on" is there for.

    Some bikes have "off" intead of "pri". On these bikes the "on" position allows fuel to run with the bike turned off so the tap has to be put on "off" when not in use. Your bike can be left in the "on" position all the time and fuel will only flow when the bike is running. :)
  9. Nup. I'm not sure if it makes a whole lot of difference, but I'd assume that the pickup for the PRI position is lower than reserve and will flow fuel regardless of demand. This might cause a problem with overflow on the carbs (it'll just spill out if there's a problem with the floats). But I'm only just getting back into carbs after 6yrs with fuel injection. :p

    BTW, there are never silly questions. Just really dumb answers! :grin: And that's what were here for...if you ever need an opinion, post on NR and you'll get one pretty soon!
  10. Would this have caused me to run out of fuel faster being on that selection? I had only done 120kms and the little beastie spluttered and coughed then stalled then took a bit to get going once i flicked down to reserve.

    I'm either thinking unreliable bike or just the fuel switch selection
  11. OH and another thought, i was on a massive hill idling in traffic, could this have caused it to flood or something being on that selection?

    Note: i am so not mechanically minded
  12. It might well be the cause. 120kms on a Bandit 250 would be really really bad. Try it on the 'On' position and I'm sure you'll notice a difference. Unless of course you were riding like Schwantz! In which case, way to go!
  13. Prime draws fuel from the lower, or reserve inlet of the fuel tap. It is used to prime carbs and fuel lines if the bike has sat for a week or so, if fuel has evaporated from the carb bowls.
    Prime shouldn't normally cause you tu use excess fuel, however, if you have stuck carburettor needles or a small leak somewhere, you could lose fuel, which would manifest itself as lower mileage.
    Check your oil for fuel, if teh oil level is higher than normal, and you have a definite fuel smell from the oil filer cap, you may have flooding carbs.
    Prime is found on vacuum operated fuel taps, and it is recommended that you select prime if you run out of fuel whilst riding, as an engine starving for fuel may not develop enough vacuum to operate the vacuum tap and allow fuel to flow from teh reserve position. So, flick it to prime and once the engine catches again, to reserve.
    Leaving teh tap on prime also has teh undesireable side effect of not leaving you with any reserve fuel, as you are drawing from teh reserve.

    Regards, Andrew.
  14. PRI is PRIME

    As hornet said.

    On and Res(erve) are switched by the vacume suction when the bike is running, so you dont have to worry about turning it off.

    Prime bypasses the switch, so that if the carbys are empty you can get the fuel back into them without the starter motor having to turn the engine over until the bowls fill (eg priming a pump).
    Also for incase the vac switch breaks.

    ON is the normal position. Get in the habit of always taking a quick look at the switch as you get on the bike, make sure its in ON position.
    If its left in reserve you will start to splutter as it runs out of fuel, "no problem" you think as you go to switch to reserve.............ahhhh poo!
    Enjoy sitting by the road for an hour while someone comes with fuel.

    But best to work out your fuel range and reset the trip counter every time you fillup. Use that to know when to fillup before you hit reserve.
  15. That is not a silly question after all.