ninjette.org - View Single Post

tpelle · November 12th, 2019, 12:09 PM

A little background - I'm thinking about getting back into motorcycling after a hiatus of around 50 years! My last experience riding a motorcycle was as a teenager on a friend's 2-stroke "scrambler", which we rode on his grand-dad's farm. My plan is to take the MSF course, then, presuming I pass, go buy a low-powered motorcycle. I've sort of narrowed my selection down to either a 2008 - 2012 Ninja 250, or a 1988 - 2007 Ninja 250. Honestly, I'm leaning towards the pre-gen, as there are several features that I prefer over the newer model - center stand, valve adjustments by setscrew/lock-nut, temperature gauge, and the traditional gas petcock. (Really, the only thing that the newer ninja has going for it, in my opinion, is the styling of the bodywork.)

I've been looking at a BUNCH of YouTube videos, and have yet to see anyone explain how to use the fuel petcock on the pre-gen Ninja to manage the gas supply. Universally, everyone extols the virtue of the gas gauge on the new Ninja, and complain about visually opening the fill cap to verify their remaining fuel.

The gas petcock is intended to provide the means to keep track of fuel usage, so if you don't know this works, it goes like this:

1. Before you start the bike up, presuming it has a full or mostly-full tank, turn the petcock to the "run" position. In "run", the taller of the two fuel pickup tubes in the tank is selected.

2. As you ride, eventually the level of gas in the tank will go down, until finally the top of the "run" fuel pickup tube will begin to uncover (intermittently due to the sloshing of fuel within the tank). At the time this happens the engine will begin to "sputter" as the supply of gas to the carburetor float bowls can't keep up with the demands of the engine.

3. Now, reach down by your left knee and switch the petcock to "reserve". This will de-select the "run" fuel pickup tube, and will instead select the "reserve" pickup tube, which is shorter. Now the engine can draw on the remaining fuel, maybe a quart or more, that is below the "run" pickup but still above the "reserve" pickup. This should be worth maybe 15 or 20 miles of riding - enough to get you to a gas station.

It's good practice, whenever you shut off the engine, to switch the petcock to "off". Yes, I know that the petcock has a vacuum valve that will shut the fuel off when the engine stops, but this might fail and possibly overflow the carburetor float bowls, which could cause gasoline to eventually contaminate the crankcase oil and cause serious damage to the engine. So getting in the habit of switching the petcock to "off" on shut-down is a good habit to acquire.

November 12th, 2019, 12:09 PM	#1
tpelle ninjette.org member Name: Tom Location: Kentucky Join Date: Jun 2009 Motorcycle(s): None yet Posts: 13	Ninja 250 Gas Petcock Use A little background - I'm thinking about getting back into motorcycling after a hiatus of around 50 years! My last experience riding a motorcycle was as a teenager on a friend's 2-stroke "scrambler", which we rode on his grand-dad's farm. My plan is to take the MSF course, then, presuming I pass, go buy a low-powered motorcycle. I've sort of narrowed my selection down to either a 2008 - 2012 Ninja 250, or a 1988 - 2007 Ninja 250. Honestly, I'm leaning towards the pre-gen, as there are several features that I prefer over the newer model - center stand, valve adjustments by setscrew/lock-nut, temperature gauge, and the traditional gas petcock. (Really, the only thing that the newer ninja has going for it, in my opinion, is the styling of the bodywork.) I've been looking at a BUNCH of YouTube videos, and have yet to see anyone explain how to use the fuel petcock on the pre-gen Ninja to manage the gas supply. Universally, everyone extols the virtue of the gas gauge on the new Ninja, and complain about visually opening the fill cap to verify their remaining fuel. The gas petcock is intended to provide the means to keep track of fuel usage, so if you don't know this works, it goes like this: 1. Before you start the bike up, presuming it has a full or mostly-full tank, turn the petcock to the "run" position. In "run", the taller of the two fuel pickup tubes in the tank is selected. 2. As you ride, eventually the level of gas in the tank will go down, until finally the top of the "run" fuel pickup tube will begin to uncover (intermittently due to the sloshing of fuel within the tank). At the time this happens the engine will begin to "sputter" as the supply of gas to the carburetor float bowls can't keep up with the demands of the engine. 3. Now, reach down by your left knee and switch the petcock to "reserve". This will de-select the "run" fuel pickup tube, and will instead select the "reserve" pickup tube, which is shorter. Now the engine can draw on the remaining fuel, maybe a quart or more, that is below the "run" pickup but still above the "reserve" pickup. This should be worth maybe 15 or 20 miles of riding - enough to get you to a gas station. It's good practice, whenever you shut off the engine, to switch the petcock to "off". Yes, I know that the petcock has a vacuum valve that will shut the fuel off when the engine stops, but this might fail and possibly overflow the carburetor float bowls, which could cause gasoline to eventually contaminate the crankcase oil and cause serious damage to the engine. So getting in the habit of switching the petcock to "off" on shut-down is a good habit to acquire.