Topic: cam constantly vents gas.

[havokhaven13]

I'm not sure if this is regular or not. This is my first bike and just learning to work on them. If i park the bike and don't close the valve on the tank then it will constantly drip gas and is a pain to start when i want to ride. This is my daily driver to and from work and other places. How can i fix this problem?

[scottly]

For starters, turn off the valve whenever the bike isn't running.

[MCRider]

For starters, turn off the valve whenever the bike isn't running.

That's right. Its SOP on gravity feed petcocks to turn them off when engine is off. So don't think of it as a hassle.

I turn it off slightly before turning off the engine to drawdown the fuel levels a bit. It will start without that flooding feeling.

Still, the petcock should hold its water. You may need to overhaul it, and I think parts are hard to find.

[havokhaven13]

thanks for that guys. i wasn't sure if it was a problem or just normal for older bikes. I'm currently rebuilding the bike a little at a time as i go along and parts are hard to find. even on ebay.

[Don R]

 I always know if I forget to turn one off. After a few days the garage smells like gas. check your oil level if it goes up or smells gassy change it out.
 The cam doesn't have anything to do with it.

[bjbuchanan]

Post some location, specs, progress, problems, pics, that kinda good stuff.

Either way turn the petcock off. In an ideal situation they won't leak. In either case there is no good justification to leave it on when there is an off switch

We like there pichuhs lol

[TwoTired]

It is routine to turn off the fuel valve when parked.  But, if the carbs overflow, it is a problem with float valve closure, which could be from particulates in the fuel, gummy deposits in the carbs, or worn irregular components.

It should be an irregularity for the carbs to overflow.  If it does it predictably each time when parked, it bears investigation as to exactly why.

1st check is to confirm it does so on the center stand as well as the side stand.  A difference here could mean burs in the float pivot mechanism. It's also helpful to identify which carb(s) are the routine leakers.

[PeWe]

I did not think about that that much back in the days with my CB750. I let it on most of the time. I was lucky that the carbs floats and valve worked and NO petrol filling the entire engine as I have read about in this forum. Nowadays always off when parked despite new petcock.

[Muckinfuss]

I destroyed a perfectly good 1966 BSA Super Lightning in 1969 by leaving the petcocks open while having a cigarette with my girlfriend.  Went back to kick it, backfired right through the Amals and voila, bonfire!

[flybox1]

"cam constantly vents gas"  lead me to think you were talking about the cam (cover) venting gas (fumes), which is discussed often here.
When referring to your gas shutoff valve, refer to it as such, or as the petcock or fuel tap.  then we'll be on the same page.

Tell us where the leak was coming from.  As TT mentioned, you might have other areas needing attention.

[754]

You have dripping gas and are not turning it off when parked? Simply turn it off and get the cabs looked at. If you pull the drain hoses off of the bowl, or say one or two at a time, put a small cup under the outlet to see which carbs leak.. Aerosol paint caps  are handy for this.

 Please list location.. Pet peeve of mine
 Can't get help from someone nearby if you don't post that info..
And for other newbies (not this one),come back and check your post, or we assume we are wasting our time.. Rant over..

[stewonepot]

Hi 754
why have members locations been removed?
regards Stew

[754]

Geez You are right.. Not there. At least he has his state in the profile..

[stewonepot]

Hi All
I should have said Stew from UK living  in southen spain near Cadiz, colorado to be exact!
cheers Stew

[754]

How about..My name is STEW, how do you do?...lol..

[Vinhead1957]

It is a symptom of float valves with weak springs or debris making its way to the valve holding it open.  We shut the petcock to prevent catastrophic loss of all the fuel in your tank.  That was one of the quirks of these bikes in the day.  Later bikes had a vacuum operated petcock.  Just get in the habit of doing it and once in a while clean that filter in the petcock out.   

[stewonepot]

Cheers Thanks Frank Stew.