turn off petcock every time after ride???

when i bought my 76-900 last year after a twenty year break between owning six or so z-1s-gpz's-z-1rs..i had forgotten wether i turned off my my gas every time i stopped riding when i was younger(and forgot a lot more things too)and i know some bikes i did some i did not for sure..I THINK???
So when i bought this one the guy said he turned it off a block before stopping and allways used the center stand to park so that the left floats would not get stuck by the carbs being leaned to one side on the kickstand.
I put some 29 smoothbores on it and have now been still turning it off whenever i remember.
If i do not turn off the petcock then my garrage smells like a homemade bomb(probably as safe too),and there is some gas drips on the sprockett cover and floor.
When i get my new petcock will i still have to turn it off after riding even around the block and everywhere i ride????Explain to a dummy how my fuel system works to make this happen ..thanks folks ..it is a smelly drag for my friends..

I turn off the petcock at night when I park it in the garage, but leave it on during the day.

They flood because you are not getting a tight seal between the needle valves and the brass seats.

you can fix that by turning the tips of the needles smooth and polishing the brass seats. If you get a good fit between them (and get the floats adjusted right), they won't flood.

trianglelaguna wrote:

... I put some 29 smoothbores on it and have now been still turning it off whenever i remember. If i do not turn off the petcock then my garrage smells like a homemade bomb(probably as safe too),and there is some gas drips on the sprockett cover and floor. When i get my new petcock will i still have to turn it off after riding even around the block and everywhere i ride????Explain to a dummy how my fuel system works to make this happen ..thanks folks ..it is a smelly drag for my friends..

Excess fuel being admitted into the floatbowl is often due to a "leaking float needle" which usually means an imperfect seal at the needle/seat interface. It's a good practice to keep the petcock turned off while the engine isn't running. Especially important with 29's which don't have an overflow circuit thereby allowing excess fuel to rise up into carb and flow toward air filter and toward engine.

Where crankcase vent hose is connected to a stock airbox, excess fuel getting inside air box from carb may drain through crank case vent hose directly into crankcase (this is bad). With pods, the excess fuel just pours out the pod filter.

Fuel from carb throat may also get into combustion chamber and flush past pistons into crankcase (just as bad).

Would sniff-test crankcase oil. Then change oil and filter. And not run the engine again until the problem is corrected.

Good Luck!

And if not already fitted, be sure to install and always use an inline fuel filter.

It's often grit and crud suspended in the incoming fuel that lodges in the float needle/seat interface and prevents complete closure.

Good Luck!

Even with new needles and seats,with the 29 smoothies(as mentioned)that have no overflow lines,I ALWAYS shut my gas off.I have a Pingel fuel shut-off that is just too easy to turn,so I do it as much as possible,and always when the bike gets put to bed for the night.

Other sources for gas drips would include leaks at:
Fuel tank;
Petcock;
Any of several fuel line connections;
Connector at carbs;
Connector between carbs;
Cracked fuel line;
Loose or damaged float bowl;
Float bowl gasket.

While checking integrity of fuel supply, would also assure carb floats are not leaking or sticking, and check for correct fuel level using the clear plastic tube test (adapted to 29's large bottom float bowl mainjet access hole).

Good Luck!

Apparently this is a common problem. From what i have read here, this has lead the manufacturers to use vacuum operated petcock valves. This prevents dummies like me from forgetting to shut them off, and making a mess on the garage floor.
I have had several bike and never had a leak, but my recent carb addition has been leaking . I replaced the float seats(tried 2 dif new ones) and they still leak so i have to remember to shut them off(remembering anything seems to get harder all the time.)
All u can do is try to clean or replace the seats and pray.Adding a good fuel filter will work in your favour.

I would, Even when they were new, common practice was to shut off fuel whenever you parked. Gas is heavy (@ 9 lbs per gallon ) and any weep at float valves has to go somewhere. none good. unless your' old petcock leaked, The only difference a new one will make is being easier to use. G

My 650 never leak when it was new but after all these years, there will be a 6-8 inches in diameter of gas on the floor the next morning even with the petcock shut off. It doesn't look like the valve is designed to seal. The shutoff valve is pretty worned out(groved) from fuel sediments. The fuel filter(mesh) has a hole in it. I had an in-line filter now but the damage is done. I'm going to check the fuel level and the needle/seat condition one of these days but for now it's being riden daily. Have to put up with the small spill and smell for now.

Gas is heavy (@ 7 lbs per gallon )

There, fixed that for you

Point still holds though.

AU Contrere. Petcock was designed to cut-off fuel. Period. manual was off/on/reserve. vaccumn, prime/on/res. float valves (in carbs) were designed to maintain to maintaine a useable fuel level within float chamber.allowing processible amounts. Petcock relieves the @ 30-40 lbs of standing fuel pressure standing on these small valves when at rest. regardless of type, petcock should competely shut off fuel flow when off. period. failure to turn off cock, or leaky vacumn petcock leads to fuel drain into eng. or floor. or both. Float valves SHOULD seal fuel flow, but often don't. a properly working petcock elimanates the need for float valves to work over time. G

I shut mine off, with it on the kick stand it leans too far and fuel leaks out of the number one carb, it over fills from the fuel in the line,
I allways turn it off even during short stops, just a habit now