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Rob's reserve tank blues

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by robsalvv, Jun 15, 2016.

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  1. #1 robsalvv, Jun 15, 2016
    Last edited: Jun 15, 2016
    So thought I'd share a little story and lesson to all you riders with a manual fuel tank reserve on your pride and joy.

    Travelling along the Westgate freeway the other night, in the cold rain, my 2002 ZX9R gave its familiar signs of needing to be switched to reserve - sudden deceleration/change in engine note.

    I knew I was going to hit reserve soon based on the trip meter (you reset your trip meter to zero every fill up don't you???). So my left hand automatically snaked down to the fuel tap with practiced ease (you know how to operate your fuel tap without looking don't you???), turned the tap back fully to reserve position and I settled in for the few seconds it usually takes for the bike to come back to life...

    "...five seconds... engine spluttering now - that's unusual... 10 seconds... um... I have no drive, no engine noise... I'm slowing down rather fast here in the RIGHT HAND LANE... quick check behind... 15seconds... OK time to get off the road... " I rolled to a stop on the shoulder of the centre median strip with the engine having failed to regain any sign of life.

    WTF?!



    I'll spare you the rest of the story - the lesson is this.

    DO NOT ALLOW YOUR TANK TO REMAIN LOW / ALMOST EMPTY FOR AN EXTENDED PERIOD OF TIME - especially during a cold snap.

    LOL I did the exact opposite even though I know better.

    Condensation will form on all that exposed internal tank surface and that condensation will collect at the bottom of the tank... which happens to be where the reserve takes its feed from. So when I switched to reserve, the carbies got loaded up with a water / fuel mixture... water doesn't ignite! lol Bike stops. Breakdown occurs.

    I'd had a low tank for a week. It had been cold and wet all week. 1+1=2, I clearly made a lot of condensation.

    Six or so 20 - 30second engine restart / cranking efforts on the side of the road finally cleared the water out and got fuel back into the carbies. Fortunately my battery was super healthy since I keep it on a trickle charger between rides. I guess that is the second lesson - keep your battery healthy especially if not riding the bike as often.

    So keep your tank full-ish, or if it's been at low levels for a while in the cold, fill up before any ride of decent length, then during the ride, occasionally switch it to reserve for a short burst while at speed on a straight road when safe to do so, to clear out any accumulated crud, sludge and water... this should ensure no nasty reserve ride blues in your future.

    - - -

    For those that don't appreciate how a reserve "tank" works - it's simply a second tapping that draws lower from the tank - as these sketches below show. You should know how much fuel is in your "main tank" and how much is in your "reserve tank" and plan fuel stops according... you do know these figures don't you???


    Some schematic representations for main and reserve fuel tap arrangements
    Motorcycle_PetcockReserve.

    feeling-reserved-21381358.
    Leftover_gas.
     
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  2. That sucks. Good lesson for new players though.

    I'm lucky in that regard, I ride daily so my tank doesn't stay low for very long.

    Oh, this prompts another tip for people with older bikes or bikes that sit with low(er) fuel levels. When you fill up, maybe every 3rd or 4th tank, pop a cap full of metho in the tank. Fuel and water don't mix, but metho and water do, and so does metho and fuel. The theory is that the metho/water mix is mixed with your fuel and burnt/spat out the exhaust. It also helps to reduce the effects of carby icing, which happened to me this morning on the way to work. Winter isn't coming, it's already fcuking here.
     
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  3. On old Italian bikes its a stiff vertical plastic tube that can fall off the metal pipe. Guess how I know that.
     
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  4. My system is even more complicated. No reserve tap, just a warning light. Which now works only intermittently, if at all :eek:
    It is unwise to disturb the seal around the fuel exit hole and warning sensor, for reasons too complicated for this discussion.
    I do however have a fallback position - the tank is split into two 'wings' which are connected at the lowest level (under the front cylinder) by a hose connected to two taps. So I close one of the taps while the tank is full. When one of the cylinders starts spluttering I pull over, open the tap and I get access to the last 1.5L on the far side of the tank, and head for the nearest servo.

    All this can be avoided by religiously setting trip meters, keeping an eye on them and filling up long before empty. Unfortunately I'm not devout enough to fill up at the end of the ride.
    This is the price you pay for being an electronics Luddite.
     
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  5. I am not a mechanic but I was under the impression that modern bikes have fuel indicators of some description because the fuel injection systems don't like to run dry. The old reserve system was likely to cause problems when the main ran out. Never had a FI bike so don't know. I do tend to rely on my trip meter as I have forgotten to switch back from reserve at fill up on an odd occasion so if I had waited for the splutter it would have been too late.
     
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  6. Yeh this thread is directed primarily at the curmudgeons who are holding onto their pre-digital masterpieces. :)
     
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  7. What's a "reserve"?

    Is that when you get to 500km and start looking for a fuel farm?

    :whistle:
     
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  8. Argh the perils: the VFR has a fuel gauge, AND a low fuel level warning light. The gauge is very inaccurate, and the warning light 'blips" when you turn on the ignition, so it works, but never any time after. I still do all my fuel calculations based on religiously resetting the odometer every time I fill up!! As you note, it's old, but it works...
     
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  9. I'm a qualified industrial chemist, been doing it for more than 30 years. It is correct that "metho" and water mix in all proportions, but how much water is already in your "metho"? At a guess I'd say at least 5%, but as water is cheaper than metho, it could be a lot more. So, if your "metho" isn't dry, when you add it to petrol the water is separated and ends up at the bottom of your tank, where it causes the corrosion you are trying to avoid by adding it in the first place.
     
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  11. I had a Bell 206L which had a 5 gallon water/meth tank to inject into the compressor for power increase: no issues carrying the mix, without corrosion?
     
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  12. Hmm interesting. The 'metho' trick is something I was taught by my father, then later re-confirmed (if you like) by most the people I know who own and ride old classic bikes. But what you say is interesting.

    It does help with easing my carby icing issues, it doesn't stop it, but it's not as bad. There was another product I was using last year that I got from Supercheap, but metho is somewhat cheaper. Maybe I should go back to the more expensive product.
     
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  13. You need to speak to PetesulPetesul - his beemer runs on dark-matter or is quantumly-entangled with his destination in a way which means he NEVER NEEDS FUEL.

    What the F^ck is burning/oxidising in that Rotax lump I will never understand........I'm pretty sure it's a crafty implementation of one of these things
     
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  14. So explain to me why, when riding up to Qld last week I was struggling to get 5lt/100km, yet today going back home I have managed a consistent 4.6lt/100km? I know I'm going down the map but I'm actually averaging a higher speed, too? (102kph for the day)

    Coriolis? Rushing to get away from Qld? State of Origin next week?
     
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  15. A combination of higher gravitational effect closer to the pole (VIC) than the equator (QLD) and the fact that there is no XXXX Beer sold here (usually)
     
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