Petcock leak NO MORE

[silverhorse47]

[QUOTE=Nessism;947379]If your float needles are leaking to the point where gas is winding up on the floor, or in the crankcase when the bike is parked, you can be assured that the fuel level in the carbs will be too high for proper running while you are on the road.



->This is not necessarily true. The needle/float combination is designed to allow fuel to flow into the float bowl when it drops to a certain level, and stop it flowing when it rises to a certain level. When the engine is running they can do this very well and still be a bit leaky, and performance will not necessarily be affected. They are opening and closing all the time anyway. A bit of leaking when they are closed isn't likely to change float level significantly in a running engine unless there is a really grave condition.

The petcock on the other hand is designed to shut off the gas supply to the bike when the engine is not running.

These are two separate functions, and it isn't entirely correct to expect the float needles, which are designed to regulate fuel level, to also perform the job of the petcock, which is designed to completely stop gas from reaching the carbs.

I think most of us would agree that in an ideal world we would go to the store and buy the right part and install it using the methods in the factory service manual. However in real life, after a decade or four of doing that, one develops a sense of what is good mechanical practice and what is not, and we make these decisions for ourselves, and when we find something that works, we sometimes pass it on. That's what makes the forum so great.

The point I was really trying to make is that it perhaps doesn't help the forum if we use words like 'cheap' or 'ghetto', or any other pejorative to describe repair suggestions. This particular one is widely accepted...even preferred... by some very fastidious mechanics. Most of us know that it's good if everything is perfect and factory and expensive all the time. However, the fact is that everything rarely is perfect all the time. Sometimes the float needles do not seal for one reason or another.

At that point, a diaphragm petcock, which is designed to stop all flow of gas to the carbs, may fail to protect your engine from hydrolock. A mechanical inline petcock is fail safe. Why knock it?

S.

[feelergaugephil]

Yes the big word is HYDROLOCK........................

For those of you that have never experienced that, or even the loud crack noise that comes with it, it's VERY EXPENSIVE.
I was not trying to skimp out on $$$$ to cut corners, I have approx $6-$7K in this bike so why would I cut corners.......
And by the way! completely rebuilt carbs (ALL NEW STUFF) including diaphrams, and NEW petcock internals, after 3 weeks the petcock gave out, I could smell the gas in the garage, so I instantly dropped the oil, and took the spark plugs out and turned her over, no issues.
So, to stop all the hassles, an inline stop switch was put on the main line.

Call it a ghetto repair or anything else, it does its job and will NEVER leak and I will never again get a HYDROLOCK.

I had a GS1000 years ago which did hydrolock, when I stripped it down I bend 2 of the conrods, when I spoke to the dealer he advised "yeah! common problem with those GS's leaking, rebuild the motor and put an inline fuel stop on it"

I put this inline stop in for 100% safety as I don't want to spend more money on my engine which I probably have $3K in it.

[Zook]

All my bikes have a Briggs & Stratton inline fuel shutoff. Cost all of $3.50 at the hardware store.
Funny....Suzukis and Kaw Concours have something in common...lousy petcocks and carb seats and needles.
On the Connies it's not a matter of IF you will hydrolock the engine it is WHEN.
On those the petcock rebuild kits are worthless and the carb seats are NOT replaceable.

Soooo...gut the petcock, block off the vacuum fittings and install the B&S valve. Problem solved.
IMO the vacuum operated petcocks were ment to mask the bad carbs until later...then you spend lots of $ if you bend a rod. And you still spend a lot to replace petcocks and needles.

It's also odd...every Guzzi I've ever owned had manual petcocks and dell'orto crbs...NEVER had a needle and seat leak fuel. I never worry about not shutting off the fuel, although I make it a habit to do so.

A check on the COG board will see LOTS of threads on this subject, while on the Guzzi board....nothing.

The GS I bought last fall had about 2-1/2 to 3 GALLONS of fuel in the engine....I didn't think it could hold that much!

[tlg1100]

my petcock leak thru vacuum hose flooding #2 cyl. diaphragm had pin hole in it.put a piece of gasket in place of rubber diaphragm and rode a few weeks like that until new one came in.put the new one in and it went bad in a month. have new one ordered at 75 bucks.the carbs did stop fuel from getting in motor with fuel going to carbs all the time.i put in briggs shut off to be safe this time.was thinking about shut off valve from j@p cycle easier to move position from on and off. had friend do damage from hydro lock hate to chance it.

[49er]

K & L kits rule

I'm surprised Bwringer hasn't weighed in on this one. I agree with his past philosophy on this matter. Buy a new stock petcock and forget about it for another 20 years of operation. You won't need to remember to turn off a manual valve, ever!!

Nessism is right. Decent needle valve assys shouldn't leak. Dellorto and Weber needles, to name a couple, will hold back up to 4 psi of fuel pressure, before flooding and engine at idle. There's no way that our gravity feed lines are running anywhere near that pressure. Decent needle valves and correctly set float heights shouldn't require a manual shut off valve. It is very convenient to have a valve or petcock, when it comes to removing your tank though! If you are in the habit of using the side stand, you do need to be precise with your float levels too.

When I rebuilt my VM carbs, I bought K & L carb rebuild kits. I only used the new bowl gaskets, needle valve assys and the o rings, out of the kits. I decided to reuse the original suzuki pilot air and pilot fuel screws as their tapers were marginally finer at the point than the replacements. Some say that this is an advantage, but I think that Suzuki went to these lengths to guarantee a very lean pilot circuit. Too lean, IMO.

Because of the quality of these carb kits, I decided to buy a K & L petcock rebuild kit. All the seals and diaphragms were precisely made and it has functioned well for the last month. My petcock did not fail, but after its last inspection, I knew that its days were numbered. Prevention is better than cure.

I know the general consensus has been not to bother with rebuild kits, but if the quality is there, why not? I'm sure that many of the kits out there are crap, but I'm just passing on my experience with this particular manufacturer.

[silverhorse47]

All my bikes have a Briggs & Stratton inline fuel shutoff. Cost all of $3.50 at the hardware store.

Ok, NOW we have cheap! Can we also achieve ghetto?

[four_shot]

clamp a pair of vice grips onto the line when you park the bike...lol


(ghetto enough for you?)

[woodman]

If the needles dont have rubber tips , a litlle mild valve grinding compound between the needle & seat and a few spins by hand will make them seal again. I guess thats Ghetto too but it sure works better then new elcheapo needles & seats that come in these fitsall carb kits

[themess]

Seems to me that petcocks were used because once upon a time, you couldn't count on the needle and seat to stop fuel flow. So petcocks were added. Do 2009 Suzukis have petcocks? Quality control should have eliminated the need. The reserve position? Bikes used to come without fuel gauges. Prime position? For something that is run infrequently and takes a lot of effort to turn over.

[silverhorse47]

clamp a pair of vice grips onto the line when you park the bike...lol


(ghetto enough for you?)

As long as they are really big and really rusty ones and they're covered in dirt and weld spatter....

S.

[feelergaugephil]

I used K+L replacement stuff.... STILL leaked after 3 weeks........

Anyway, DONT use my idea, have peace of mind, cos your petcock will never leak!!!!!!!

PLEASE POST PICS OF YOUR BENT CONRODS, I NEED A LAUGH GUYS!

Dont take my advice, I have used this method countless times without incident.

I guess the Suzuki dealer was wrong too all those years back......

[Nessism]

I used K+L replacement stuff.... STILL leaked after 3 weeks........

Anyway, DONT use my idea, have peace of mind, cos your petcock will never leak!!!!!!!

PLEASE POST PICS OF YOUR BENT CONRODS, I NEED A LAUGH GUYS!

Dont take my advice, I have used this method countless times without incident.

I guess the Suzuki dealer was wrong too all those years back......

If your bike has leaking float needles and seats, and you added a manual shut-off valve instead of fixing the bike properly, the first time you forget to turn off that shut-off valve your engine is going to be full of gas. This constitutes a MUCH greater risk of bent connecting rods than replacing the defective parts and eliminating the problem at the source.

BTW, in the years I've been hanging around the GSR I can't remember one occurrence of someone bending connecting rods on their GS. Not saying it can't happen, but it seems to me that the risk is quite low.

[silverhorse47]

BTW, in the years I've been hanging around the GSR I can't remember one occurrence of someone bending connecting rods on their GS. Not saying it can't happen, but it seems to me that the risk is quite low.

From 'old q&a':

"...My suspicion is that there is a very small "pin" hole, or very small crack, in the diaphragm allowing raw fuel to be sucked into #2 cylinder. The hole (leak) is small enough to only noticeably affect lower engine speeds, and not large enough to flood the entire cylinder. If the leak becomes severe the #2 cylinder could fill with enough raw fuel to fill the compression space when the piston is at top-dead-center (TDC). THIS CAN CAUSE SEVERE ENGINE DAMAGE, AND LOSS OF CONTROL IF IT HAPPENS AT SPEED. What happens here is that liquids cannot be compressed like the normal fuel air mix. The #2 piston comes up and hits the liquid filled space and causes an engine wreck (bent connecting rod, blown out upper or lower connecting rod bearing, or if you are lucky only a blown head gasket or blown out sparkplug). I have a clear vacuum line on my GS850 (see fuel being sucked in), and I am in the process of adding a manual in-line (Briggs & Stratton) fuel shutoff valve down stream of the "automatic" petcock. My "automatic" petcock did not shut-off completely. I smelled gas in my garage and saw that gas wetted the bottom of the the air-box. I pulled the carbs, removed the plugs, propped the plug wires high up out of the way and cranked the engine. Fuel shot out #1 & #2 spark plug hole like a hose. This could have been a disaster had I cranked the engine normally and #3 or #4 cylinder fired (engine wreck mentioned above), or something in the starting motor linkage broke trying to compress the liquid fuel. Good luck!!!..."

S.

[Gimpdiggity]

I can see both sides of the issue.

I had an old Yamaha YX-600 Radian. Loved that bike, but almost every week I'd go out and it would have leaked gas all over the garage floor. Out went the old oil, in went the new, and it would always start right up.

Because I didn't feel like tearing the carbs apart I did the trick in this thread. I just threw the shut off valve in line and was done with it. However, it was about a month before riding season was over and I was planning on doing the carbs again that winter.

So when the carbs came off and I found the culprit (stuck float valve needle) I fixed it and I didn't have the leak anymore ever.

However, I still used the shut off valve whenever I was going to leave the bike sitting for more than a few days. It just added a little bit of peace of mind for me.

Is it a Band-aid fix?? Yes. But does it work?? Yes, as long as you remember to use it.

I still believe that fixing the source of the problem is for the best...but if you are in a pinch this will work well UNTIL you can fix the root problem.

[silverhorse47]

I can see both sides of the issue.

I still believe that fixing the source of the problem is for the best...

Yes, I agree, and I also agree that most of us can see both sides of the thread.

But the point, perhaps, is that the "source of the problem" is a leaky petcock...not stuck or worn float valves, as some would have us believe.

The solution to a leaky petcock is a new petcock, either inline, oem, pingel, briggs or whatever floats your boat. Float valves are designed to maintain the level of fuel in the bowl...and by doing that to meter fuel from the bowl to the jet. They are NOT to stop fuel entering the engine.

Float valves stick, the floats themselves hang up, and in general this mechanism cannot be relied upon to always be free of leaks.On the other hand, with a running engine, they do a good job of maintaining the fuel level in the float bowls, so that the jet circuits can work properly. When float valves screw up, and they do....as forum members have affirmed...the only thing that provides real peace of mind is a reliable mechanical petcock and a brain, which we all either have or are in the process of acquiring, so that we remember to use said petcock.

I think that is all the original post was meant to suggest. That, and a welcome reminder that trusting your old motorcycle engine to your old vacuum operated petcock (or even your recently rebuilt cherry set of carbs with their expensive new float valves) is likely a bad bet.

The petcock has to work all the time. Get used to it.

S.