Petcocks ?

[madmax-im]

I've had them on my XJ1100Maxim and other XS1100s..On the maxim i would run the bike with petcocks in "on" position...when the level in the tank dropped the engine would stutter but still run...indicative of the time to turn the petcocks to "Res"..
On my XJ is was a pretty smooth transition. As soon as the petcocks were turned to "Res" then the engine would pick right back up where it left off... On my XS1100s that transition was always cold blooded and i would actually have to pull off the road to wait for the gas to flow once again..Instead of using the "on" position..i would fill the tank up and leave the petcocks in "Res"...I would always be aware of the Odo readings for tank range and would avoid the cold blooded transition from "on" to "res"..
So my question to you all is about how you use your XS650 petcocks while riding.?
Do you all turn them to "off' when you park the bike in your garage..shed..house..what have you?
My inclination is to just run the bike with them in "res"...as for when its parked..not so sure...

 

[gggGary]

The 78 up petcocks are vacuum operated like your other Yammies and don't have an "off" position. I use the on position and buy only genuine Yamaha 4 hole rubber "valves" They can be fussy to get to hold a seal and not leak.
I can usually feel it going lean and get the petcock switched to reserve without pulling over. but yah gotta move on it.

 

[madmax-im]

Hmmm..The petcocks on the Special Two have an OFF position...

 

[xjwmx]

I can usually feel it going lean and get the petcock switched to reserve without pulling over. but yah gotta move on it.

On mine, it's a little bit of stumbling and some lean popping.

 

[gggGary]

Hmmm..The petcocks on the Special Two have an OFF position...

May have been replaced with manual ones.

 

[madmax-im]

heres a shot...

 

[madmax-im]

I'm confused as to why there are manual petcocks and if that means i have to use the "off" position when the bike is parked???
Oh and my other Yammies had the "Off" position too...If it is a vacuum system perhaps that negates the "off" position?

 

[xjwmx]

^With vacuum operated, absence of vacuum turns it off. Manual, you have to turn off. Float needles and seats don't guarantee a 100% seal, only enough seal to keep the bowl levels right.

 

[Gator xs2]

I always turn my fuel valves off. And I too believe in OEM. I bought a pair of fuel valves from Mikexs and was very hesitant about using them. They just seemed cheesy. They’re probably fine but I decided to go with OEM.

 

[madmax-im]

^With vacuum operated, absence of vacuum turns it off. Manual, you have to turn off. Float needles and seats don't guarantee a 100% seal, only enough seal to keep the bowl levels right.

Ahh..That makes sense..but now i have to question Phil as to what it is i have..vacuum or manual? Not understanding this one...

 

[member28833]

In your pic I see the vacuum port/pipe on the intake manifold in front of the carb is capped with a rubber plug. I assume both are the same ?
It appears your petcock have been “upgraded” to manual,

 

[650Skull]

Yea best to shut Petcocks off when not riding................You have Manual Petcocks............Vacuum operated petcocks are attached to the inlet manifolds by a tube that operates and opens the petcock when the engine is running............in this pic you can see the vacuum tube has been caped off, one on each inlet manifold.......

NOTE.... this is important, Tattoo under eyelids............ if the caps come off the tube then the bike will run Very Very lean and very rough and no power

 

[madmax-im]

In your pic I see the vacuum port/pipe on the intake manifold in front of the carb is capped with a rubber plug. I assume both are the same ?
It appears your petcock have been “upgraded” to manual,

Yes the other side is capped off too...How is this an "upgrade"?

 

[Gator xs2]

You sure that ain’t for carb sync?

 

[member28833]

Yes the other side is capped off too...How is this an "upgrade"?

Many XS owners have had trouble with the original vacuum petcocks leaking and gave up on them switching to after market manual petcocks.
I personally much prefer good working vacuum petcocks. Especially with 78/79 series BS38 carbs which do not have a float bowl drain pipe on the bottom.
Your float needle and seats are most likely fine. If they should fail. Carb overflow of gasoline could either flow rearward into the air box, or forward drooling into the crankcase oil.
I would also encourage using the “off” position when parked.

 

[madmax-im]

Definitive answers from the man himself...So all is as he intended it to be..that may not be what everyone else has or knows...but thats just how it is..

 

[650Skull]

You sure that ain’t for carb sync?

Not the original reason for................but...........can be used as a carb sync if not running vacuum petcocks .............but...........cannot be used as a carb sync if running vacuum petcocks

Postscript.........read post #20

 

[madmax-im]

Many XS owners have had trouble with the original vacuum petcocks leaking and gave up on them switching to after market manual petcocks.
I personally much prefer good working vacuum petcocks. Especially with 78/79 series BS38 carbs which do not have a float bowl drain pipe on the bottom.
Your float needle and seats are most likely fine. If they should fail. Carb overflow of gasoline could either flow rearward into the air box, or forward drooling into the crankcase oil.
I would also encourage using the “off” position when parked.

Interesting..things on my bike are not stock..as they might appear from 10 ft away..I will use the "off" position when parked..but i will ride with them in the "Res" position and just watch my odo...

 

[member28833]

.I will use the "off" position when parked..but i will ride with them in the "Res" position and just watch my odo...

Hold on there.. try this. At fill up reset your trip meter to 0 . Run with the petcock “on” until the engine sputters lacking fuel. Note the miles traveled. Switch the petcocks to “res” for additional run distance, go for fuel.
Sound reasonable ?
-R

 

[xjwmx]

can be used as a carb sync if not running vacuum petcocks .............but...........cannot be used as a carb sync if running vacuum petcocks

If you have vacuum pets just put it on "pri" or prime to do the sync. Flows there w/ no vacuum.