Carb or petcock problem

[dluszcz]

I have a 78 GS1000E that I've been tinkering with for almost 2 years resurrecting her. Not all stock. I have pod filters and a 4 into 1 exhaust.

I have rebuilt a complete set of carbs (courtesy of a very good GSR member), installed the O-ring kit and boot o-rings from Mr. Robert Barr. I completely disassembled the carbs and dipped everything that I could. Used a nylon brush to get the harder stuff off. Per the advice of people at Z1 and on here, I moved the needle to position #4, installed 102.5 main jets, and thought that the rebuild went well. Bike is running, but extremely rich.

I did some research and some of the symptoms point to a bad petcock. Mine is brand new (well, it was when I bought it last year, a universal from Z1 Enterprises) and shouldn't have any issues.

Problem is, carb #3 (which I have been mistakenly calling carb #2) has a lot of fuel coming out of the overflow tube after a bike ride. Ends up being about the size of a baseball on the cardboard box that I have placed under my bike to check for leaks.

Came across some threads that state it may be a bad petcock. I pulled the vacuum hose from carb #2 and sure enough, there is some fuel in there. And, when I took the oil cap off and smelled it, smelled like gas.

So, now I am a little more confused than I was before I started doing some research on my problem(s).

Is it possible that I have a bad petcock? Is it something more serious? And, what is the cheapest JASO-MA type oil that I can buy? I am currently using Shell Rotella, but if something is cheaper and works the same, I would like to save a buck or two when possible.

[janner]

sounds like a petcock problem , my oil is smelling slightly whiffy too, i am about to re-build my carbs and give them the once over, but am going to replace the petcock same time and hopefully will sort mine out, but as you seen fuel in the vac line , then it suggests petcock problem !! also double check the float heights once more too .. jon

[dluszcz]

I'm going to put my money on the float height measurement. Part of the reasoning for this is below. The other part is that I bought a brand spanking new universal petcock from Z1 Enterprises last year and with just over 200 miles on the bike since the purchase, I can't see it failing.

I know that I was in a rush to get these rebuilt to run it the next day, the only day in the Chicagoland area in the last God knows how many months where the temp touched 80 degrees. And that was almost a month ago.

So, I'm going to take the carbs off tomorrow and check the float height. I can say with some certainty that may be part of the problem. After I confirm that are in spec, which according to the book is 23mm-25mm, I will take her out for a spin and see what difference it makes.

If anyone has any other ideas, I would love to hear them. I won't be yanking the carbs off until I get home from work tomorrow so I will be more than happy to hear other ideas before I tear into it.

[Nessism]

My guess is there is gunk holding the float needle open on that #3 carb. Is the tank clean?

[dluszcz]

Last fall, I had the tank baked to get the Kreme out of it. Then, I took it to a radiator place in Woodstock, IL that lines gas tanks with a guarantee. I've had zero problems with that any kind of debris in the fuel.

In addition, I have a clear gas line and I have a fuel filter installed just before entering the carbs.

However, since the NASCAR race just started, I decided to pull the carbs and take a measurement of the float heights. All were about 1mm from each other, but none of them reached the 23mm line on my piece of cardboard that I used to measure them.

So, I bent the tabs enough to be a tad below the 25mm line. And, all appear to be at the same spot on the cardboard. Now, I just have to install the carbs tomorrow and see if that made a difference.

If I go on the upper end of the range, does that mean that the float will shut off fuel at a lower level? I'm not certain on how that works in the carbs.

And, if I should go for the middle, 24mm, someone let me know. I've never rebuilt carbs before so I'm happy that I've reached this point.

[chuckycheese]

Yeah

My guess is there is gunk holding the float needle open on that #3 carb. Is the tank clean?

That would be my first guess, too!

[Nessism]

Sounds like you carefully set the float heights...but that overflowing carb says something is wrong. How about making up a float height gauge with a piece of tubing? Might be time to confirm the fuel level directly.

[dluszcz]

This is the 2nd float needle that I have put in carb #3. The 1st needle was clogged. When I first put the carbs back together and set the petcock to prime, gas went all over the floor until I moved the petcock back to on.

Then, I hit the bowl with the back of the socket wrench and the leaking stopped, for a little bit.

Took the carb bowl off and noticed that the float needle was very sticky. So, I tossed it in the garbage and grabbed another one. This time, I checked it before I placed it in the holder and the spring was good.

But, like I stated earlier in this thread, I didn't check the float height and I'm wondering if that is where my problem is. They were all out of spec, but just barely. Only one of them was more than 1mm out of spec.

Since the carbs are still off the bike, I may choose to grab yet another float needle and change it out again, just to make sure. Also, maybe I'll put all 3 that I have left back into the carb dip for a bit and then rinse and blow out with compressed air. I can't see the harm in that, even if it's not completely necessary.

Also, something that I noticed when removing the carbs, the intake boots on all 4 were moist with gas on the bottom. Is that normal?

[dluszcz]

Responding to Nessism's post, I don't know how to check the fuel level directly with a piece of tubing.

I still have a couple of inches of clear fuel line left, if that is the right diameter tubing to use.

Also, since I have reset the float heights, I haven't reinstalled the carbs and tried the changes yet.

If someone can tell me how to check the level with the tubing method, I would like to try that before I put them back on, just to make sure they are correctly set.

[cowb0y]

It might be time to pick up a digital caliper. I bought mine for something like $15 and have used it at least a dozen times on my bike. Rebuilding carbs are made much simpler with the right tools. Just a thought.

[dluszcz]

Never even heard of a digital caliper until I looked it up on Google. I didn't know that was what it was called.

Obviously, I'm a newbie with regards to acquiring the correct tools to do the job right!

Sears, Home Depot, and Lowes all have a digital model that is under $20. Thanks for the advice.

I may pick one up after work and before I install the carbs just to make sure that they are all the same height. Maybe then I could get them to 24mm, right smack dab in the middle of the specs.

[Nessism]

Responding to Nessism's post, I don't know how to check the fuel level directly with a piece of tubing.

I still have a couple of inches of clear fuel line left, if that is the right diameter tubing to use.

Also, since I have reset the float heights, I haven't reinstalled the carbs and tried the changes yet.

If someone can tell me how to check the level with the tubing method, I would like to try that before I put them back on, just to make sure they are correctly set.

The factory service manual shows how to measure the fuel level. You can make a level gauge by drilling the appropriate size bolt and gluing in a piece of tubing, to which you can attach the clear tubing.

The photo below shows how I made some sync adapters. Making a fuel level tool is the same, but the threads are different.

[Matchless]

If I may suggest check the fuel levels and any overflowing with the carbs off the bike, just use a dummy tank or container.

Also test the petcock properly, connect a longer pipe to a clear container and shorter one to the vacuum nipple. Check that it flows freely on prime, on run and reserve it should only flow if you suck on the vacuum pipe and cut of completely when you stop sucking. No fuel should leak from the vacuum nipple on the petcock at any setting.

[dluszcz]

OK, I've ruled out the petcock. I had the tank off the bike and put a tube to the vacuum inlet. Put another tube on the fuel outlet.

Turned the petcock to prime, gas came out. Shut it off, gas stopped instantly.

Sucked on the vac tube and gas came out. I stopped, the gas stopped.

Moved the petcock to RES. Sucked on the vac tube and same result.

Moved the petcock back to ON and started the bike. Ran OK. No popping though.

In the process of changing the oil because it smelled like gas.

Hopefully, the only issue was the float height.

[dluszcz]

Had it running for about 10 minutes and did a couple of laps around the block. When I shut it down and let it sit for a while, that would've meant a baseball sized wet spot on the cardboard.

This time, no wet spot. So, taking the wife for a little ride. Hopefully, all will be well. When we get back and I let it cool down a bit in the garage, I should hopefully still have no wet spot from the overflow tube.