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Comment by 0_____0 | Hacker News Reader

always fun when you're barreling down the highway and the engine starts to lean out, prompting you to hurriedly locate and switch the petcock over before the engine stalls completely.

suppose then that you go fill up and forget to set the petcock back to normal. 8ball says: "I see a long walk in your future."

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IME it doesn't take too many hikes to learn that part of the procedure for turning off the engine is "turn the fuel switch off reserve".

out of years of riding it's only happened to me a couple times.

one time i was eastbound on the bay bridge when my bike started to sputter. i'd just reassembled the tank and had left the screw-style reserve fuel valve open, so there was no reserve fuel to be had. a very kind lady put her blinkers on behind me and followed as i coasted the last few hundred yards toward yerba buena island.

i pushed my bike up the ramp and looked in the tank to assess. it's a dirtbike, so the tank has two distinct "lobes" to accomodate the top tube of the frame. I had a few ounces in the tank but they were not in the lobe with the fuel pickup, so i dumped the bike on its side to get the fuel to slosh over to where i wanted it.

i got back on the highway and, going quite slowly and gently, managed to get to the gas station at west oakland bart, the engine leaning out and sputtering right as i rolled into their lot.

I think that driving on those last few ounces of fuel is a completely different feeling.

Normally you take for granted that the engine works for hours at at time.

When you've come to a stop and found those last few ounces of fuel, it's such a relief that the engine can run again, and you know it won't run for very long, but every minute that it continues running saves you many minutes of walking or pushing. You appreciate every minute that the engine produces that amazing amount of power (compared to your own power when you're pushing a 300+ pound bike)

It's a crazy amount of energy. The 2.5 gallons of gas that that tank holds has more energy than all the food I eat in a month.

I once put a new fuel pump in a Chevy pickup with two tanks on the side of the road because I was switched to the empty tank. Good times.

Surprised there isn't a mechanism that mechanically switches the petcock over when you put a fuel nozzle up to the port

Typically there aren't two separate tanks - In one tank there are two tubes at different heights. As the fuel level falls below the height of the "main" tube the engine sputters, then turning the petcock engages the lower down "reserve" tube which is still below the fuel level. It's more of a warning than a true reserve, and most bikes with an actual fuel gauge don't have a reserve.

On bikes like that, there's a reserve-reserve trick sometimes. Sometimes, the tank is an inverted U shape so when the pickup runs dry there's still a little more fuel on the other side of the U. If the bike is light enough, you can stop the bike and lean it way over to pour that last bit over to the pickup side. Might get you another couple miles.

Most motorcycles are surprisingly manual. This was originally a necessity (like in cars), but remains aesthetically preferable for many riders.

OTOH, Honda Goldwings have stereo systems. They might grow an automatic fuel reserve switcher-backer someday too. :)

Fuel injected motorcycles don’t have reserve (at least, none that I’ve seen.) instead they have low fuel lights or full fuel gauges. I’m guessing it’s because the fuel pumps are in the tank and the fuel injection system needs high pressure.

Fuel injectors require filtered gas because even small particles can clog them, and said filter is more likely to be clogged or even compromised by sucking up the last drops of fuel (and scale and debris) in the tank, so the low-fuel warning is required.

Carb jets can get clogged, too, but are wider since they're not under as much pressure. Also, since they're a wear item they're a lot easier to clean and/or replace.

I think grandparent commenter had it right: it's because the pump is in the tank. There's just no good way to have an external petcock determine where a tank-internal pump gets its fuel from.

Many new bikes come with a lot of rider aids for safety (ABS, TCS) as well as all kinds of electronics (fuel maps), so this is changing. But of course manual transmission won't go away until bike are electric.

I am one of those who likes things old school. My bike still has a carburetor, has no fuel light or tachometer, and I have certainly had some practice reaching down to turn the fuel petcock to reserve while sputtering on the highway. If they didn't intend for me to do that, why did they put it on the left side? :)

> But of course manual transmission won't go away until bike are electric.

See multiple Honda bikes with DCT (dual clutch transmission). This is what I'm planning to get as my first bike.

Goldwings also have a reverse gear. Even more remarkable: I used to have an Aprilia scooter that had a remote release button (on the key fob) for the under-seat storage area. I think I used it once just to see if it works.

Some newer bikes, like mine, don't have a reserve petcock. They have a low fuel light. No forgetting about the petcock and an obvious warning light instead of sputtering.

Some older bikes, like my '99 Ducati Monster, don't have a petcock. It has a low fuel light that first failed in around 2002, and for which that part that fails (the in-tank float switch) stopped being available in about 2015 or so. No petcock _or_ warning light. (And that trip where the speedo cable fails so I couldn't even use thew trip meter to estimate fuel requirements was a fun one...)

Can you find someone who can adapt a float switch from a different bike? It seems like a very useful thing to have, even if it's not the original factory part.

I've just gotten used to it. I'm fairly reliable about always resetting the trip meter when I fill it up (and always fill it to full). I know it'll get 200km easy, maybe only 180 if I'm having _way_ too much fun. That's always about time I want to stop and stretch my legs anyway. It doesn't bother me enough to "solve the problem".

Most motorcycles with a manual petcock are very manual in nature. Often this is to minimize the number of moving parts that could die on you if you take it into rural areas. An automatic petcock adds more complexity that could cause a malfunction.

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