New guy with bad problem

[oneliterbeater]

You should test your petcock - any fuel in the vacuum line?

Vacuum line? I saw a nipple on the petcock that wasn't being used. Could that be where a vacuum line should be? If so, where is it supposed to hook up on the other end?

I know I sound like an imbecile (and kind of feel like one) but I really do own tools and know how to use them. Just never worked on motorcycles much.

[nufnuf]

Unless your petcock is set on prime,your bike will not run with the vaccume hose not attached.
If your petcock is shot, or set on prime fuel will flow into the carbs.
When your carb bowls fill the floats rise and shut off little valves which prevent overflow
Your carbs have overflow hoses directing fuel to the ground if this happens but it is also possible for fuel to leak down the throat of the carb past the piston to the sump.
Thats why you may have fuel in your oil
This will lead to your bike being broken if not addressed
If your confident none of the above is happening, get some new oil
NOT JUST ANY OLD OIL. If you happen to put an oil with friction modifiers in your bike your clutch will probably fail
the vaccume hose runs from the inside body of number 3 carb directly to the petcock
A little bit of information can be a bad thing.
My best advice would be to take some time to research these questions on this site
There is nothing the guys on this site dont know about gs's and all from first hand experience
The cranck case breather hose is not essential and will not affect how your engine runs
The vaccume hose however is essential and if your bike can run without it connected potential disaster aint too far away

[cableguy]

The service manual is downloadable from Basscliff's site (see mega-welcome), if you haven't already found it. No shame in being a decent mechanic but ignorant about GS's (me too), but search first then post, because the question you have has probably been covered, and also put as much info about your bike as possible in your signature for speedy and efficient responses. Cool bike you got there BTW

[oneliterbeater]

A little update.

I ran around town today and picked up a Suzuki filter and new o ring, some oil, and what I thought would be the right size tubing for the crankcase breather. I was wrong. Anyway, I'll be making another trip to the parts store.

I bench tested my tank petcock. I poured a little gas into the tank and hooked up some fuel line I had laying around and put the other end in my gas can. Gas will flow when set to Prime. Will not flow when set to ON or RES. So I hooked a little piece of vacuum tubing to the nipple on the petcock and applied vacuum. Gas flows now. So, that tells me that the petcock is ok.

What isn't ok is that it must have been running on the PRIME setting before I got it. I found where the vacuum line is supposed to go on the carb (thanks to this site and the pictures on bikecliff's site) and it has one of those little nipple covers over it. So, I'll be getting that straightened out also.


Just wanted to say thanks for all the tips so far. I have been searching and reading here and hope to learn more as I go. Thanks for being patient with me and I'm still trying to get the hang of the search so I'm not asking redundant questions.

[Smokinapankake]

The search function is an okay tool if you know what key words to use. I've found, however, that it will return an unbelievable amount of information for you to sift through; most often I just don't have the time to go through all of it.
BassCliff's site is, in my opinion, more useful than searching.

[Nessism]

The search function is an okay tool if you know what key words to use. I've found, however, that it will return an unbelievable amount of information for you to sift through; most often I just don't have the time to go through all of it.
BassCliff's site is, in my opinion, more useful than searching.

Use Advanced Search and Titles Only to hone in quickly.

Regarding this petcock, one last thing to do is put a piece of clear tubing in place of the vacuum hose to make sure fuel is not flowing backwards down the vacuum line.

[oneliterbeater]

Another update:

Well, I got it put back together today. Put the new filter in, the CORRECT amount of oil, and got the breather tube on and a vacuum line from the carb to the petcock.

It runs! AND it doesn't blow oil all over. No leaks so far either. I think I lucked out on that.

I'm 80% sure that my petcock is working correctly, but I'm starving for fuel if I run it on ON. There is enough fuel in the tank, but I'm not sure I have the vacuum line connected in the right spot.

I used Bikecliff's page here for reference:

http://members.dslextreme.com/users/storagecliff/images/hose_locations.html

My petcock is different in that my fuel outlet is on the opposite side as the one pictured. Also my carbs look different than the one on that page. Maybe it's just the difference between the 850 and 1000.

I should have taken some pictures while I had it apart. I will try and search here for some 1000 carb pics.

Anyway, thanks for the help so far, and I'm just happy that I've made some positive progress.

[oneliterbeater]

Not been so lucky finding what I need in the search. I'm sorry for being a pain, but does anyone have some detailed pictures of the carb and lines setup for a gs1000?

[mjremington]

Well I'm not as smart and knowledgeable as most of these guys are but the line on cylinder one carb goes to the fuel, the one in between 1 and 2 (closer to 2 on the carb body) goes to vacuum. then there is a breather/vent that goes down from the backside middle on my GS750T. I have the Mikuni 32mm. Not sure if they're that different. To be safe, the rebuild kits are cheap for the petcock and you can get after market for 30 to 50 and OEM for 70.

[mjremington]

Actual replacement petcocks for 30-70. Should of clarified. The rebuild kit is like 12. A good test is to remove the vacuum hose from the carb. Then the fuel line from the carb. Manually suck on the vacuum line with the petcock in the "on" position. Fuel should flow. If its running good in the prime or reserve but not ON. Then it could need a rebuild or replacement. But try that test. If it operates well then its more 98 percent the petcock is good. But I havent read the entire post but I'm figuring they've been cleaned and rebuilt so the carbs should be working properly.

[BassCliff]

Hi,

The hose setup is a little different for the '79 bikes and their VM carbs. You will get the vacuum feed from the #3 carb instead of the #2 carb (like the CV carb models). The petcock you describe is an aftermarket replacement which should be functional but perhaps not as robust as an OEM part.

Thank you for your indulgence,

BassCliff

[Big T]

Actually, Cliff, the 1000 petcock is different. The fuel outlet is straight back on the right and the vacuum port goes up at an angle. Like this







That's the original petcock from my 78

Oneliter - your carbs are different from those BS carbs. The fuel line goes to the T in the middle and the vacuum house goes right next to the fuel on the inside of #3 carb.

The other 2 lines are vents

[mjremington]

See, I told you these fine people were more knowledgeable. And now I know the difference in the two setups!

[oneliterbeater]

Excellent! That's just what I needed . Thanks so much.

[BassCliff]

Hi,

Actually, Cliff, the 1000 petcock is different. The fuel outlet is straight back on the right and the vacuum port goes up at an angle.

Thank you Mr. Big T. Nice pictures.

From the description I thought a previous owner may have replaced the petcock with something like this from Z1Enterprises:



So, nevermind.

Thank you for your indulgence,

BassCliff