I think I may have found my problem!

[Guest]

Well I have been pulling my hair out over my 750 and its running issue. I have been having issues with it loading up and running rough. I would always clear out if I rapped up on the throttle. So here is what I did recently: First off I turned in my mixture screws 1/2 turn and I lowered my needle on clip. I thought this took care of my issue but today it did it again and was running real rough. Once home I pulled all of the plugs and to my surprise cylinders 1,3.& 4 were in pretty decent shape however cylinder number two was extremely fouled. So I got thinking what is special about #2. Well it turns out this is the carb that the vacum line runs off for the petcock. I pulled of the line and it was not dry as it should be it was wet with gasoline. I assumed then that it must be drawing extra fuel into cylinder #2 and that is why it is fouling. I pulled the end off of the petcock and plugged the line. I will now run it and see what happens. Has anyone had any issues like this before? If this cures the problem I am going to be on the market for a new petcock. Anyone have any suggestions as to a stock or aftermarket petcock (pingle)? I have a trip planned next friday and I need to get it done asap.

[Smokinapankake]

Have not had the issue you described but go to www.z11enterprises.com You should be able to source a fuel valve (petcock) for around 40 bucks.
Good luck and keep us posted!

[Smokinapankake]

whoops not z11enterprises but www.z1enterprises.com

[Zook]

Be careful doing this. Why?
With the vacuum line removed you will have to set the petcock to the "prime" position, so fuel will always be flowing through the valve. IOW, it doesn't shut off, even when in the "off position because the diaphragm is leaking.

You will find out overnight if you have bad carb needles and seats. The second you hit the starter the engine will hydrolock, possibly bending a rod.
Or, the gas will leak past the rings and into the crankcase, and you won't know it.

Don't ask how I know....

[NetBSD]

Be careful doing this. Why?
With the vacuum line removed you will have to set the petcock to the "prime" position, so fuel will always be flowing through the valve. IOW, it doesn't shut off, even when in the "off position because the diaphragm is leaking.

You will find out overnight if you have bad carb needles and seats. The second you hit the starter the engine will hydrolock, possibly bending a rod.
Or, the gas will leak past the rings and into the crankcase, and you won't know it.

Don't ask how I know....

yep my cousins yamaha 850 midnight special was doing this, leaking thry the rings and into the crank because of a bad petcock. you can pickup a set of manual petcocks cheap and do away with the vacume ones if you want.

[Zook]

yep my cousins yamaha 850 midnight special was doing this, leaking thry the rings and into the crank because of a bad petcock. you can pickup a set of manual petcocks cheap and do away with the vacume ones if you want.

YEP!
I hydrolocked a Concours once. Hit the starter and, "CLANK". Had to pull the plugs and crank the engine-with the coils disconnected....

Tried a rebuild kit I got for free, that didn't work (don't ask) so I went to the local hardware store and bought a Briggs and Stratton shutoff valve. Cost a whole $3.50.
My GS is getting one and my Guzzi got one when its valve started leaking.

Call me cheap....er, frugal.

[Steve]

One other little tidbit to keep in mind if you are using the PRIME postion on the petcock ... there is no RESERVE.

Yep, if you go until you feel it run out, then try to switch to RESERVE, you may as well figure on walking or pushing.

.

[SqDancerLynn1]

It's actually a common problem when the petcock goes bad. Best solution is a new one. Make sure the tank is clean too. Don't use ethenol gas if you can avoid it.
On the VM carbs it effects the #3 carb

[TheCafeKid]

yep my cousins yamaha 850 midnight special was doing this, leaking thry the rings and into the crank because of a bad petcock. you can pickup a set of manual petcocks cheap and do away with the vacume ones if you want.

Untill one day you forget to turn it off, then you will have BIG problems. Generally, the float valves are designed to hold back fuel from spilling over into the crank case, but unless you've replaced them, and even if you have (the replacement ones tend to be a bit weaker in the spring department) they're not going to hold back that pressure for long. Vaccum petcocks are fantastic, replace it once every 15 yrs or so, and you're golden.

[doug g]

I already thouhgt about the facxt that I could dump fuel in the crankcase however I have been turning it to the on position when not in use. i also knew that I would not have a reserve. I do want to know if I should go with a stck or aftermarket petcock on the bike. Thoughts?

[Steve]

As mentioned before, the stock vacuum petcock might have to be replaced every 15-20 years, but can basically be ingored in the interim, except for the occasional change to RESERVE position.

Most aftermarket petcocks will be manual, which means you will be learning new habits concerning moving it to ON every time you ride and then to OFF when you stop.

Your choice. Personally, I would go with a stock vacuum unit.

.

[TheCafeKid]

*I* am not a fan of the Pingel, or the knockoffs of that type. It just leaves too much to risk. I have a couple of NON Suzuki bikes here as well, and they are all fitted with vaccum type petcocks. They're all 26 years old, and they all still function as they should. Incidently, the petcock off my Yammie will bolt right up to my Zook 750, and vice verse...and ANOTHER thing Clarence... It just so happens i JUST yesterday ordered a new petcock for my 750, got a stocker. I have faith in it 41 bucks from Z1 and i wont have to order another one probably in its lifetime. She's a tough old b!tch that 77 750, but somehow i think that she just wont make it another 20 years...

[Zook]

I already thouhgt about the facxt that I could dump fuel in the crankcase however I have been turning it to the on position when not in use. i also knew that I would not have a reserve. I do want to know if I should go with a stck or aftermarket petcock on the bike. Thoughts?

RED FLAG!!!

Your petcock is bad right now. Turning it to "on" doesn't stop the fuel flow due to the diaphragm being torn. That's why fuel is getting into the intake, the petcock is bad.

It matters not if you use manual or vacuum petcocks you have bigger problems if your carb needles and seats leak. Your bike will leak all thefuel in the bowls into the cylinders every time you shut off the engine.

[Steve]

Your bike will leak all thefuel in the bowls into the cylinders every time you shut off the engine.

I agree with the RED FLAG, but there is always the chance that your float valves are still working and will shut of the fuel flow into the carbs like they are supposed to.

However, it is just as likely that they won't, so order your new petcock, but drain the tank into a safe container until you get the new petcock installed.


Second thoughts here, after re-reading your original post: your petcock diaphragm is leaking, and that puts fuel into the carb after the float valve, so the engine will still flood. Order your new petcock and drain the tank.

.

[Zook]

Finally had a cuppa, woke up and realized the fuel in the bowls won't leak into the cylinders when not running...that fuel is UNDER the needle, but if they are bad they may not shut off while riding and flood the engine.

There, that's better! :-)