Possible petcock problem/taking off gas tank?

[Guest]

Hey guys, super beginner here with a super beginner question. I started on a valve adjustment for my 79 550e yesterday. Started with taking off the tank. The guide says to unhook the vacuum and fuel line from the petcock in order to take the tank off. When I went to pull off the first line, which I believe was the fuel line (it ran from the petcock to the carbs), gas was coming out at a steady rate. The petcock was set to on, so this shouldn't be the case, right? With the line connected correctly, there isn't evidence of a leak anywhere that would lead me to believe that gas was constantly running into the carb bowls. No gas beneath the bike, oil level steady in the sight, etc. Am I doing something wrong? If the petcock was broken and it leaked fuel constantly into the bowls, wouldn't there be evidence of a leak?

[JTGS850GL]

Your petcock is indeed bad if it's providing fuel with it in the on position. The reason you don't have any leakage after the tank is because your float bowl valves are in good working order. The vacuum operated petcock is designed as an added safety measure incase of a leaking float bowl valve. You need to replace the petcock ASAP as it can create some big issues when (not if) one of your floats begins to leak.

[Steve]

Are you sure it was in the ON position? Should have the lever pointing DOWN.

JT is right, you are lucky that your float valves are in good condition.

There are "petcock rebuild kits", but the overall success rate seems to be about 10-15% on those, so rather than waste your time on money on one, then having to get a new petcock anyway, just bite the bullet and get the new petcock first.

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[BBoh21]

Yeah the petcock was definitely facing down in the on position. I also moved it to both res and prim while leaking to see if it would stop it (surprise: it didn't).

The previous owner said he went through the carbs not too long ago, which I'm assuming is why the float valves are in as good a shape as you guys say. When I bought it off him a couple weeks ago it was running fine, but now won't start anymore. Would this be the problem for that?

With some help on here it seems it needed a valve clearance adjustment (where this fiasco started) and/or carbs cleaned. I didn't think he lied to me about him just cleaning the carbs, which it appears he didn't, so I don't think that's the problem.

Also, looking at new petcocks, if I were to order a "petcock assembly" (1-3 on the link) would that include the gaskets, rings, etc. as well, or do I need to order all those separate parts along with that?

http://www.partsoutlaw.com/oemparts/a/suz/50d3f5a0f8700230d8b4c700/fuel-cock

[JTGS850GL]

Item 1 should contain everything needed including the gasket between the petcock and the tank.

[Steve]

When you order your petcock, be sure to also get items #4 and #6. (Note that you will need two of #6.) Sometimes you will get #4 with the petcock, but it won't hurt to have a spare.

With regard to "carb cleaning", some people think that dropping the float bowl and spritzing some carb cleaner spray in the general direction of the jets constitutes "cleaning the carbs". As you might have guessed there is a little more to it than that. Click HERE for your own key to our library, then click HERE for the carb rebuilding guide.

While you are visiting the library, be sure to check out the valve adjustment tutorial. If you have questions (and you certainly will), be sure to ask.

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[JTGS850GL]

So far every OEM petcock I've ordered has come with the item #4 gasket. It's part of the assembly #1. Aftermarket petcocks are a crap shoot on if they include that part or not. Agreed that #6x2 is going to be needed as well.