TOPIC:

Reading other topics, understand whats' going on with factory vacuum operating petcock. So, unless I "PRIME" - petcock should not let fuel in unless there is vacuum (engine running)
Got it. Looks like little overkill IMO, but also prompts a question.

How do you store bike for longer periods? Let's say I want to park for a winter. I prefer carbs to sit empty. With regular valve I can just shut it and run until dies. But with regular petcock it's not possible.

How do you guys avoid long sitting fuel in carbs/ethanol issues, etc?

And another thing about leaks
A. Petcock fails - fuel goes to carb, but should not leak?
B. Carb needle doesn't hold and let fuel in - overflowing, fuel should go to the floor
C. Not going to the floor, going inside engine

So, 3 things have to fail to get fuel into engine during parking, correct?

But with regular petcock it's not possible.

Just put the petcock to ON.
Pull the vacuum line to the petcock at the carb.
Plug the carb vacuum fitting.
Run the engine.
That should get the bowls close to drained.
You'll have to pull the bowl or open the drain plug to get most of the fuel out.

Just pull the vacuum hose from the carb and plug it. Then run the engine until fuel runs out.
If your fuel needle is not shutting off then you have to resolve that issue. 

I always drain the carbs for Winter storage.

I've switch to a manual petcock.
I bought this one, 44 mm spacing:

44MM KZ650 KZ750 KZ650SR GPZ750 GPZ KZ 650 750 MANUAL KIT PETCOCK FUEL VALVE | eBay


 

If the petcock fails and fuel goes to the carb via the vacuum line, fuel will get into your engine. If the petcock fails and fuel goes to the engine via the fuel line, then yes, the needle and seat would also have to fail, or your float levels be set too high, or your overflow tubes get plugged, for fuel to get into the engine. 

By katit:  With regular valve I can just shut it and run until dies.

Just in case you aren't aware.  Doing it this way doesn't drain the carburetors >> there will still be some fuel in the bowls.  The engine just runs until it can't pick up fuel any more, then dies.  

Clamp the vacuum line shut with g clap, small grips or similar, saves having to disconnect and block ports etc.
start engine and run until it starts to die then lift choke lever increasingly until it dies on full choke.
The choke pick up is lowest point in the bowl after the drain screw so if it's dies on virtually full choke then both jets and all passages will be fuel free and won't clog.

For me the easiest thing is to keep the bikes wet and running this way seals don't dry out and leak when you want to use it, i always get out at least once a fortnight to keep it running this empties the fuel in the carbs, i also use a fuel stabilizer.

wrote:

I always drain the carbs for Winter storage.

I've switch to a manual petcock.
I bought this one, 44 mm spacing:

EDIT: at just under 500 KMs, this petcock has FAILED!
When off, it constantly drips.
It doesn't flow well when ON.
The lever is getting hard to turn.
Haven't taken it apart yet.
Ethanol in the gas may be a contributing factor.