Gas tank petcock variations

[ResidentWarui]

Sorry for posting twice on the same problem, but this is a much more general question...

Did any of the petcocks used on the 77-86 GS models not have gas filtering screens attatched to them? Is it safe to use a petcock without a screen?

I am asking this because I bought a 78 GS550 petcock for my 78 GS550 and expected them to be identical but the one I ordered came with no screen and my current screen wouldn't fit.

TIA

-Simon

[LW_Icarus]

all of em have a screen on the petcock as their primary fuel filter as far as I know.

[ResidentWarui]

is it safe to run one without a screen? or is it possible to buy a replacement screen?

[ZacharyB]

It's safe to run it without a screen, it may just become troublesome later on if a tiny piece of debris goes into the carbs, where it can plug a jet. Install a lawnmower fuel filter in between the tank and the carbs if you end up not being able to find a screen

[ResidentWarui]

Thanks man

[ResidentWarui]

Hmm, I just pulled the screen out and the first thing that I noticed is that it is leaking gas again without vacuum like the old petcock did... is a filter of some kind necessary to equalize the pressure?

it wasn't leaking gas minus a few drops with the screen in there... help me get to the bottom of this mystery, i don't want wet plug again tommorow morning!

[ResidentWarui]

Sorry for all the reposts but this update is important:

I rode the bike all the way arround campus fine with the fuel screen removed the only problem is these two things. 1. It's leaking gas on the on position without vacuum like the old petcock did with the screen. (As I said in my last post. After posting that I walked out to the bike and a ton of gas was being dumped out of the overflows on the carbs even as I walked up.) and 2. It's running so rich that it idles at 3000RPM and I have to open the throttle to bring it down a lil.

Is the fuel filter a necessary thing for keeping the pressure stable on a working petcock? And if so will the inline filter help restrict the excess flow as the screen in the petcock?

While I await your kind replies I am going to throw the screen back in so that it won't leak when I go to Kragens to buy an inline filter.

TIA

Simon

[ResidentWarui]

Update:

Changed the screen. Leak is gone, but again I suspect the flow is too restricted causing stalls.

TY those of you who read this crap and my other thread as well.

[ccratin]

did you buy the second petcock used? Sounds like you have a bad diaphragm. The petcock should not leak if it is in the "ON" position regardless of whether or not there is a screen installed. If you are running really rich, a bad diaphragm could be allowing fuel to be pulled through the vacuum line going to the petcock and richening things considerably. Try removing and plugging the vacuum line and then running the bike with the petcock on prime. If it runs normally, then this is likely your problem. you can easily rebuild the petcock.

[ResidentWarui]

Thanks for the reply, I'll give it a shot.

I think it's important for you to know as well that the thing is dumping tons of gas onto the road whenever I shut it off through the overflow tubes off the carbs. I get a puddle going in about 2 minutes. I guess it's not getting in the engine, but it sounds like a bad petcock to me...

Is there anything I can do to fix these things? I haven't seen the rebuild kits arround anywhere.

-Simon

[ccratin]

You can find the rebuild kits from cycle re-cycle for a little over $20. They have the new diaphragm and o-rings. You problem right now sounds like it may also be related to the carb float needle valves. Try what I told you on the petcock and see if you still have the same issues. If so, carbs, if not, petcock. On my bike, I had both!

[ResidentWarui]

Thanks for the reply...

I got enough homework this weekend to last a month. (Yea I'm really lazy, but it's seriously enough to keep a busy student inside without break the whole weekend, plus I already spent the whole night/afternoon hanging out with my girlfriend.)

Tommorow I'll hike over to the lot that I dumped my bike in and see if I have any luck with it. I seriously better get started on that petcock bussiness because they have a 10 day return policy and $30 seems a bit steep for a busted petcock.

-Simon

[LW_Icarus]

even if the petcock were stuck wide open, your bike should not dump gas onto the pavement. the needles and seats should stop fuel flow before they overflow. check float adjustment, make sure the floats are still bouyant, and check/replace needle valves.

it DOES sound like the petcock isnt shutting off fuel, but thats not the entire problem

[ResidentWarui]

Yea I know my carbs are all 8O as well. Replacement parts on the way.

Need to go pick up a bucket of parts cleaner for next weekend.