Happy times! I just took my 97 on its first long-distance (more than 100 miles) trip yesterday.

I ran into one issue and one question. First off, there appears to be a problem with my petcock. Riding along at 70+ in 6th, the bike would run fine for about 10 miles and then, almost like clock work, it would start acting like it was running out of gas. I'd have to pull off, sit there and wait, and then continue on.

I decided to test a theory and put the petcock on PRI. I rode the remaining 80 miles on PRI without a single hiccup. So, that pretty much guarantees that the petcock is malfunctioning. What can/should I do about this? What's strange about it is that so long as I stay off the highway, I'd never know anything was wrong with the bike - it seems like the issue only arises when it's ridden at a steady speed for long periods of time.

As a side-question, which can be answered for extra credit: I noticed that my airbox "pee pee-thing" was wet with what appeared to be very very black oil/funk/fuel. Am I to assume that during extended highway riding, the GS has some oil get into the airbox from the valve cover vent line, and that this is normal? I remember my KLR650 doing the same thing.

On many bikes, including the GS, the crank-case breather line feeds into the airbox. Oil mist, combustion byproducts, etc. end up in the airbox because of it. Some bikes put a filter of some sort over the line, others (like the GS, IIRC) do not.

Quote from: burning1 on February 28, 2012, 11:02:07 AM
On many bikes, including the GS, the crank-case breather line feeds into the airbox. Oil mist, combustion byproducts, etc. end up in the airbox because of it. Some bikes put a filter of some sort over the line, others (like the GS, IIRC) do not.

That's what I wanted to know. Thanks.

since burning1 is on top of the breather,

Remember, every time you open the throttle, you will cause a drop in manifold pressure proportionate to the throttle opening.

The petcock runs on vacuum, as most do, but maybe sitting, or just being old, or your vacuum line, somewhere in there you have a vacuum leak most likely. At lower vacuum, the petcock is not supplying sufficient fuel.
I'd try replacing the vacuum line between the carb and petcock, and move along from there.

I replaced the whole system, but that was my prerogative, adidasguy likes the vacuum petcocks, and asserts they are good. Which is true, many bikes now, and then use them just fine!
The choice, as they say, is yours!


edit- Apparently when i shorten petcock to c o c k it turns into chicken.

As they said:
* Check vacuum lines
* Check the tiny hole around your gas cap. That let's air into the tank. If clogged, the tank develops a vacuum and won't let fuel flow out.
* Check for pinched fuel hoses or added fuel filters (which can restrict fuel flow)

PRI pretty much means vacuum to the pet chicken or petcock is going bad.
PRI pulls from the reserve line. Possible your main fuel line is kinked.

I only had it happen to me once. That was when I bought Junior and had to go 40 miles on I-5 to get him home. He dies 10 minutes out. Went to PRI and was fine. Since then, he has never done that. Could have been the petcock (pet chicken) was stiff or something else. The more he's ridden the better he runs.

Quote from: adidasguy on February 28, 2012, 12:11:24 PM
As they said:
* Check vacuum lines
* Check the tiny hole around your gas cap. That let's air into the tank. If clogged, the tank develops a vacuum and won't let fuel flow out.
* Check for pinched fuel hoses or added fuel filters (which can restrict fuel flow)

PRI pretty much means vacuum to the pet chicken or petcock is going bad.
PRI pulls from the reserve line. Possible your main fuel line is kinked.

I only had it happen to me once. That was when I bought Junior and had to go 40 miles on I-5 to get him home. He dies 10 minutes out. Went to PRI and was fine. Since then, he has never done that. Could have been the petcock (pet chicken) was stiff or something else. The more he's ridden the better he runs.

Yes, of course those are the obvious things. However, consider the relationship between "PRIME" and the vent on the tank -- there is none. Therefore, if putting the petcock on "PRIME" fixes the issue, you can eliminate the vent as the culprit. "PRIME" adds no additional venting capability.

The fuel lines are not kinked. I'm 100% positive on that. I'm also certain that the line going to the petcock is fine as I just replaced it.

You say that "PRIME" draws from the reserve line? Well, I'm pretty sure I'm not running out of gas 30 miles after I fill up. The skies are supposed to clear later on, so I'll get out and give it another go on reserve and see if it still exhibits the same issue.

Perhaps there is something stuck in the petcock causing it not to open intermittently?

Possible the petcock diaphragm is stiff or has a hole.
Not sure what you mean by "running out of gas after 30 miles" 
There is no "reserve tank". The reserve line takes gas from a lower point in the same tank.
ON and RES rely on the vacuum for fuel flow. PRIME overrides the need for the vacuum and draws fuel from the RES fuel line.

He meant that it is not an issue of having to switch to prime because he's low on fuel because he just filled up 30 miles ago.

The short answer:  The problem is in your vacuum petcock if "prime" setting stops the condition.  If you are getting a good vacuum signal at the hose, replace the faulty petcock.

-Jessie

Quote from: BaltimoreGS on February 28, 2012, 01:23:07 PM
He meant that it is not an issue of having to switch to prime because he's low on fuel because he just filled up 30 miles ago.

The short answer:  The problem is in your vacuum petcock if "prime" setting stops the condition.  If you are getting a good vacuum signal at the hose, replace the faulty petcock.

-Jessie

Correct, that is what I meant. The vacuum at the hose is quite strong.

I'm just perplexed by the whole thing because of the very specific conditions for it to become a problem. I've never had a problem with it around town and it was only until I hit the interstate that I had a problem. I had the same thing happen before I rejetted the carburetors once before on my way to work but I attributed that to just a random gremlin - it is now obvious that there is an issue.

Are there other options besides just going with an OEM petcock? A new one is $70... I realize the risk of the "standard petcock" because of the weak float needles.

Maybe I should try taking the petcock apart first and see if I can determine what's wrong with it.

QuoteMaybe I should try taking the petcock apart first and see if I can determine what's wrong with it.

That is good way to start. Like adidas said, the diaphragm may need to be exercised or replaced,

If you really want to get rid of the whole thing, you can, i put up a post about my method, you can probably search it. If that floats your boat.

Quote from: Funderb on February 28, 2012, 02:52:30 PM

QuoteMaybe I should try taking the petcock apart first and see if I can determine what's wrong with it.

That is good way to start. Like adidas said, the diaphragm may need to be exercised or replaced,

If you really want to get rid of the whole thing, you can, i put up a post about my method, you can probably search it. If that floats your boat.

I recall your post, yes. I may end up doing that.

I wonder if it's even possible to rebuild the petcock? RonAyers just shows it as an entire assembly. I found a "K&L" petcock for $45... http://www.oldbikebarn.com/Fuel-Petcock-Suzuki-44300-01D21?sc=2&category=167672 Maybe this will be the ticket?

It sounds as though over time, the fill rate into your carb bowls is slower than the rate at which the fuel is burned. So, after 10 minutes or so, the bowls are dry, and your bike starts to sputter.

Around town, you're probably consuming gas at a slower rate, and giving the float bowl enough time to fill up.

Quote from: burning1 on February 28, 2012, 03:33:34 PM
It sounds as though over time, the fill rate into your carb bowls is slower than the rate at which the fuel is burned. So, after 10 minutes or so, the bowls are dry, and your bike starts to sputter.

Around town, you're probably consuming gas at a slower rate, and giving the float bowl enough time to fill up.

Exactly   

-Jessie

Quote from: Kijona on February 28, 2012, 02:56:38 PM

Quote from: Funderb on February 28, 2012, 02:52:30 PM

QuoteMaybe I should try taking the petcock apart first and see if I can determine what's wrong with it.

That is good way to start. Like adidas said, the diaphragm may need to be exercised or replaced,

If you really want to get rid of the whole thing, you can, i put up a post about my method, you can probably search it. If that floats your boat.

I recall your post, yes. I may end up doing that.

I wonder if it's even possible to rebuild the petcock? RonAyers just shows it as an entire assembly. I found a "K&L" petcock for $45... http://www.oldbikebarn.com/Fuel-Petcock-Suzuki-44300-01D21?sc=2&category=167672 Maybe this will be the ticket?

My petcock is jacked and refuses to work on reserve, so I'm going to end up using Funderb's method.  For simplicity, cost and peace of mind.

Quote from: Kijona on February 28, 2012, 12:37:39 PM


Yes, of course those are the obvious things. However, consider the relationship between "PRIME" and the vent on the tank -- there is none. Therefore, if putting the petcock on "PRIME" fixes the issue, you can eliminate the vent as the culprit. "PRIME" adds no additional venting capability.

Maybe I'm reading this wrong, but the vent on the tank affects all the gas flowing to the carbs if the vent is clogged. No air going in to replace the gas going out= fuel starvation.

And stay away from OldBikeBarn at all costs. It's basically one guy running the site from his basement. You order a part, then he orders it for cheaper, then sends the part to you with a little mark up. Google some reviews if you'd like.

I have difficulty with the mentality of replacing something broken with something completely different. If something breaks, do you always rip it out and put in something totally different?

Seems when someone has a problem with the petcock (which are not very many people) they are so vocal they make everyone think they are bad.

There are thousands of bikes with vacuum petcocks. They work. When one goes bad, just get a new one or a good used one.

Lots of parts on your bike go bad. If a chain goes bad, do you say chains are bad and replace the drive train with a shaft or belt? If you get a flat tire, do you decide to change brands of tires rather than fix your tire?

I have issues with the mentality of scrapping everything and starting over from scratch when something breaks.... rather than looking at what is broken and fixing it or improving it.

Get a replacement petcock. 3 minute replacement and you will know it will work. Rip it out and go with something different: you can have a new set of problems.

Quote from: adidasguy on March 01, 2012, 12:05:59 AM
I have difficulty with the mentality of replacing something broken with something completely different. If something breaks, do you always rip it out and put in something totally different?

Seems when someone has a problem with the petcock (which are not very many people) they are so vocal they make everyone think they are bad.

There are thousands of bikes with vacuum petcocks. They work. When one goes bad, just get a new one or a good used one.

Lots of parts on your bike go bad. If a chain goes bad, do you say chains are bad and replace the drive train with a shaft or belt? If you get a flat tire, do you decide to change brands of tires rather than fix your tire?

I have issues with the mentality of scrapping everything and starting over from scratch when something breaks.... rather than looking at what is broken and fixing it or improving it.

Get a replacement petcock. 3 minute replacement and you will know it will work. Rip it out and go with something different: you can have a new set of problems.

I'm not saying that, Adidas. I wasn't saying the petcocks sucked or anything along those lines. All I was saying was that it seems absurd to pay $70 plus shipping for something so inconsequential. There's only one on fleabay and it looks ragged out and it's expensive.

Quote from: Big Rich on March 01, 2012, 12:05:42 AM

Quote from: Kijona on February 28, 2012, 12:37:39 PM


Yes, of course those are the obvious things. However, consider the relationship between "PRIME" and the vent on the tank -- there is none. Therefore, if putting the petcock on "PRIME" fixes the issue, you can eliminate the vent as the culprit. "PRIME" adds no additional venting capability.

Maybe I'm reading this wrong, but the vent on the tank affects all the gas flowing to the carbs if the vent is clogged. No air going in to replace the gas going out= fuel starvation.

And stay away from OldBikeBarn at all costs. It's basically one guy running the site from his basement. You order a part, then he orders it for cheaper, then sends the part to you with a little mark up. Google some reviews if you'd like.

What I was saying was that if the vent in the tank was clogged, putting it on prime would have no effect whatsoever - i.e., the "PRI" setting has no relation to the vent on the tank. The fact that putting it on prime does fix the issue, points to an issue with the petcock. I'm going to take it apart first, see if it's something obvious, and if it's not I'll see if I can find one of those K&L petcocks somewhere. If not, I'll just figure something else out. I'm not paying $70 for a valve, and I'm not taking any chances on fleabay - especially when the only one available says "returns not accepted".

Thanks for the heads up on OldBikeBarn. I'll keep that in mind.

What about this?
new
Suzuki GS500 GS500E GS500F Fuel Petcock Gas Tank Switch
 
Seller User ID: peakmoto-powers...
Feedback: 98,014 | 99.8%
From United States
AU $41.36   +AU $11.13   Time left:22d 13h 24m

http://www.ebay.com.au/itm/Suzuki-GS500-GS500E-GS500F-Fuel-Petcock-Gas-Tank-Switch-/380414189477?pt=Motorcycles_Parts_Accessories&hash=item589273dfa5

Or a used one

http://www.ebay.com.au/itm/1991-Suzuki-GS500-GS500E-Fuel-Switch-Petcock-/250999726996?pt=Motorcycles_Parts_Accessories&hash=item3a70bfe394#ht_4244wt_1163

1991 Suzuki GS500 GS500E Fuel Switch Petcock
Item condition:   Used
US $16.99

OK. So before you go ripping things out and changing things, why not ask a parts whore if you could try a new petcock or two then see if it works? Then  return it or pay for it? A couple petcocks is $5 postage in a flat rate box.

Unless there us a design improvement, I feel we should replace parts and make things work as designed.

We have a few parts whores here. Not always necessary to deal with ebay or BikeBandit.

There are ways to test a petcock. maybe I should do  a video this weekend? Need to re-shoot some scenes for the electrical system. Could shoot petcock testing.

We should be working together in swapping parts to get bikes working with OEM parts  rather than having parts sit on the shelf or hack things into something of a completely different, untested design.

Doing this will also be a valuable learning process for all of us regarding the parts in out GS500's. I have a few bikes to look at and a lot of spare parts. We parts whores would serve the community by loaning pout extra parts to see if that fixes their bike. If it does, then they can pay for the parts. If it doesn't fix it, return the parts. Documenting what happened will add to the loads of knowledge for the WIKI.