Wouldn't start, then trouble idling

[mark]

Yeah, you pretty much have to go through it all......

You can test your petcock pretty easily. Pull your vacuum line off the carb, put the petcock to "ON" and suck on the vacuum line. Gas should start flowing from your petcock. If you suck in a bunch of gas (be careful) then you'll redefine "having gas" and have something else you need to fix.

Probably started the third time when you opened the throttle because it was flooding a bit by then..........when you let in a little air it fired.

[UncleMike]

Yeah, you pretty much have to go through it all......

You can test your petcock pretty easily. Pull your vacuum line off the carb, put the petcock to "ON" and suck on the vacuum line. Gas should start flowing from your petcock. If you suck in a bunch of gas (be careful) then you'll redefine "having gas" and have something else you need to fix.

Probably started the third time when you opened the throttle because it was flooding a bit by then..........when you let in a little air it fired.

Okay, that makes sense.

When I pull the vacuum line, put it to "ON" and suck on the line, gas should or shouldn't flow? You say it should, but also say that if it does, I'll have something else to fix. Were you referring to a mouthful of gasoline, or would the petcock then have a faulty diaphragm.

Or is this whole thing a long-distance practical joke, with the goal of getting me to drink gas in retribution for the political/relgious threads?

[Billy Ricks]

Okay, that makes sense.

When I pull the vacuum line, put it to "ON" and suck on the line, gas should or shouldn't flow? You say it should, but also say that if it does, I'll have something else to fix. Were you referring to a mouthful of gasoline, or would the petcock then have a faulty diaphragm.

Or is this whole thing a long-distance practical joke, with the goal of getting me to drink gas in retribution for the political/relgious threads?

With the petcock on either run or reserve the petcock should hold vacuum when you suck on the smaller vacuum line and fuel should flow from the fuel line. If you get a little gas in your mouth while sucking the diaphram is toast. You can use a large syringe to provide sunction if you don't want to risk gas in your mouth.

[UncleMike]

With the petcock on either run or reserve the petcock should hold vacuum when you suck on the smaller vacuum line and fuel should flow from the fuel line. If you get a little gas in your mouth while sucking the diaphram is toast. You can use a large syringe to provide sunction if you don't want to risk gas in your mouth.

So of the two lines coming off the petcock, I can see a big one that disappears in the middle of the back of the carbs, and a small one that connects to the middle of the front. I want to pull off that smaller line and suck on it, and fuel should flow from the larger fuel line, but not into my mouth?

[Billy Ricks]

So of the two lines coming off the petcock, I can see a big one that disappears in the middle of the back of the carbs, and a small one that connects to the middle of the front. I want to pull off that smaller line and suck on it, and fuel should flow from the larger fuel line, but not into my mouth?

Correct. If you get fuel out of the vacuum line the diaphram is toast.

[flyingace]

This is probably gonna sound stupid, but I guess I'm just trying to eliminate the possibility that it could be a problem with the petcock, or that the valves need adjusting, or something electrical, before I tear apart the carbs. I'm so ignorant when it comes to this, that I don't even know if any of those are possibilities. Thinking it's time to adjust the valves anyway,...

I haven't yet heard anything that sounds like it's broken. It starts and runs with choke, and, until I hear otherwise, runs OK when warm. It almost sounds to me like an unwillingness on your part to use the choke until the bike is warmed up.

[UncleMike]

Correct. If you get fuel out of the vacuum line the diaphram is toast.

Okay. Now, just to be clear, when you say fuel should flow from the fuel line, what do you mean? The action of my sucking will cause fuel to flow from the tank down the other line into the carbs? Is my sucking mimicking the vacuum flow that would normally occur during operation?

Sorry I'm so slow at this, but it's a symptom of not knowing how the petcock works. I'll have to get a spare and take it apart.

[UncleMike]

I haven't yet heard anything that sounds like it's broken. It starts and runs with choke, and, until I hear otherwise, runs OK when warm. It almost sounds to me like an unwillingness on your part to use the choke until the bike is warmed up.

A bit, yes, but my main concern is the reluctance to start without starting fluid. Although that wasn't an issue this morn.

[Billy Ricks]

Okay. Now, just to be clear, when you say fuel should flow from the fuel line, what do you mean? The action of my sucking will cause fuel to flow from the tank down the other line into the carbs? Is my sucking mimicking the vacuum flow that would normally occur during operation?

Sorry I'm so slow at this, but it's a symptom of not knowing how the petcock works. I'll have to get a spare and take it apart.

The smaller line is only supposed to allow for vacuum to be applied to the diaphram in the petcock. No fuel should be present in it and it should hold vacuum if you put your tongue over the end of the vacuum line while sucking on it. Remove the fuel line to the carbs at the petcock and attach a piece of fuel line to the outlet to see if fuel runs out of it when you apply the vacuum. You can run that fuel line into a bottle or something to keep from making a mess.

[UncleMike]

The smaller line is only supposed to allow for vacuum to be applied to the diaphram in the petcock. No fuel should be present in it and it should hold vacuum if you put your tongue over the end of the vacuum line while sucking on it. Remove the fuel line to the carbs at the petcock and attach a piece of fuel line to the outlet to see if fuel runs out of it when you apply the vacuum. You can run that fuel line into a bottle or something to keep from making a mess.

Very interesting. Thanks!

That's 5/16 right?

[Billy Ricks]

Very interesting. Thanks!

That's 5/16 right?

Sounds right. Anything you can find that will fit over the outlet will do.

[smithbm]

It sounds to me like you just need to find out what choke position your bike likes. Try starting out with the choke only 1/2 or 3/4 open then close it up little by little as the bike warms up. I leave the choke on until my bike is completely warmed up (approx. 5 to 10 min). When it was running, that is.

[UncleMike]

Sounds right. Anything you can find that will fit over the outlet will do.

Thanks. And thanks to Mark and flyinace for sticking through this, even with my ignorance.

Mike

[smithbm]

The smaller line is only supposed to allow for vacuum to be applied to the diaphram in the petcock. No fuel should be present in it and it should hold vacuum if you put your tongue over the end of the vacuum line while sucking on it. Remove the fuel line to the carbs at the petcock and attach a piece of fuel line to the outlet to see if fuel runs out of it when you apply the vacuum. You can run that fuel line into a bottle or something to keep from making a mess.

You can also accomplish this with a hand vacuum pump from your local auto parts place if you’re not into the whole gasoline in mouth thing.

[UncleMike]

Petcock diaphragm is a-okay! No gas in the mouth.

Took her out to start her. Petcock on "ON" and full choke with no throttle, she started immediately up. Idled at around 1100 for a second or two, then steadily climbed to around 3200rpms. After that for a second, idle started dropping again and would threaten to stall if I didn't "blip" the throttle and actually hold it a bit open, but just the smallest bit. Just enough to put a bit of pressure on the throttle.

After only about three minutes, she would idle without any choke at 1000rpms. It seemed like it was staggering a little bit, as the handlebars were vibrating enough to shake the right mirror to rattling a bit. But still, I'm very happy.

I wish I had heard other GS engines besides this one. I can't tell if it sounds good or not. There seems to be a "hissing" coming from the top end of the engine. Not sure if this is normal or not. Also sounds like there's a slight, low rattle as well. It's not high-pitched. This seems a little futile without you guys hearing it as well. I'm just reluctant to take it to a mechanic who knows nothing about GS's.

Like I said though, I'm very happy. It's getting better everyday, and I haven't even ridden it yet this year. Next is cleaning all the connections and testing the electrical system. I also read something about cleaning the oil strainer in the pan. Add it to the list,...

Thanks guys,
Mike