Fast Idle Issue

[mike_of_bbg]

Second Mighty Mike of BBG (Please tell me that's the Brooklyn Botanic Garden)

Not mighty here - I'm about as noob as you are And no, the bbg is from my current home town of Blacksburg. Nothing Botanic. Some people have green thumbs, some brown: I have a black thumb. I look at plants and they die. That is, if I want them to grow. If I don't then they'll grow like weeds (which they probably are).

As soon as it fired it began pouring gas out of the rubber hose that is apparently coming out of the mysterious intake boot.

Let's get this straight first.

There are two hoses which connect to the petcock: a fuel hose (duh), and a smaller-diameter vacuum hose which connects to a tap on carb #2. The vacuum from carb #2 goes through this hose and pulls a diaphragm which allows fuel to flow when your petcock is in the ON or RES positions. THERE SHOULD NOT BE FUEL IN THE VACUUM HOSE! If there is fuel in the vacuum hose, then that diaphragm probably has a tear in it, and the whole petcock should be replaced (very limited reports of success on rebuilds). Since your bike is an 80, it probably has that oddball petcock with no PRI position (which would allow fuel to flow without the vacuum).

Also, if you disconnect the vacuum line, you must plug the tap on carb #2 (or plug the hose if you left it in the carb and unplugged the petcock end).

High idle is caused by too much air getting through (or around) the carbs. If your intake boot o-rings are original, then it's likely they need to be replaced, and they can definitely leak some air. But I kinda doubt that they suddenly went from stable 1200 RPM to 4k RPM. So, some things to check:

1. Is your petcock vacuum tap on carb #2 open? If so, carb #2 can suck air through it, bypassing the throttle.

2. Did you replace the plugs on the intake boots after doing the carb sync? To do the sync the plugs come out and taps go in: to which hoses for the carb sync gauge are connected. Those taps allow air in (which I mentioned before). Make sure the plugs went back in and are snug.

3. Is the choke operating freely? The so-called "choke" on these Mikuni carbs is actually a fuel enrichment circuit which allows an enriched fuel AND AIR mixture through the carbs. 4k RPM is not unlikely with choke stuck open.

4. Did you adjust any of the screws when you did your carb sync? The point of the sync is to adjust the relative opening of the throttle plates on each carb (eventually all relative to #3, the master carb on 4-cyl GSes). If one or more carbs are closed too much, that can cause the others to hang open and let too much air in.

5. Sticking throttle cable? There should be about 1 mm of slack in the throttle cable.

When you replaced the air filter, did you just replace the foam element? Did you oil it? Is it back in tightly?

[Rudi]

Mike,
First, you lucky thus-and-such. I went to college about an hour north of you in Harrisonburg. The 81 corridor has got to be one of the most beautiful places on earth. Regarding your "noob" status, I'm afraid I was unclear. I'm both a noobie and hopelessly incompetent - see the difference? Thanks for the clear talk through. Point by point,
1) Vacuum tube seems to be on the straight and narrow - dry as minister.
2) I'll be rechecking the plugs after supper...
3) Choke appeared to be free, but I'll give 'er another peek.
4) My bike started yarfing fuel through the tube feller (see post from 07-02-2010 05:06 PM) so I haven't gotten around to syncing the carbs.
5) I'll be checking the throttle cable.
Thanks for all the suggestions, we'll see what happens next.

Steve,
I'm afraid I'm a bit more toppish on the left hand side. Just a smidgen north of Lima. Also, I have a high concentration of ignorance, so I'd be a bit concerned that the dumb might rub off on a visiting expert. (Osmotic pressure and what-not...8th grade science wasn't my strong suit.) All the same, if there is someone roughly in the area and you're up for the live comedy of me with tools, stop in and I'll be glad to feed you. Just send me a message through the board and I'll send you address and contact info.

Regards

[Dave8338]

Please forgive me if I missed something, but have you gone through the carbs and cleaned them yet? I only ask, as this is a MUST, prior to getting the "old girl" feeling frisky, gain.

[Rudi]

Fair enough...the fella who sold me the bike said he cleaned the carbs thoroughly this Spring. He had street bike and had bought the GS for his wife who simply didn't like her. He was quite honest with me in his dealings and I believed him regarding the carbs. I drained the tank and put in fresh gas with fuel stabilizer/carb cleaner.

[mike_of_bbg]

Ah. So by "intake boot" in your earlier post you probably actually meant your airbox vent hose? Airbox as in that wondrously odd black plastic box between your metal air filter box and the carbs?

Did you have fuel dripping down from any of your carb bowls?

Is your oil overfull? Does it smell like gasoline?

Might want to give the float bowls a rap with a block of wood. Sounds like you might just have a stuck float needle. That might explain the gas, if not the high idle...

A "thorough" carb cleaning to the folks on this board has little relation to what most would consider a thorough carb cleaning. As in, complete disassembly and 24 hours min per carb soak in your choice of carb cleaner (usually Berryman's or Gunk). No rebuild kits, but fresh o-rings from Robert Barr (www.cycleorings.com).

Ah, Harrisonburg - or as my wife knows it, home of the closest Kohl's

[Rudi]

Ahh...back to Panicking

First off...in response to the great Mike of Blacksburg, I misnamed the what's-it. I should have called it the other what's-it.
However, I have new problems. I took a few weeks off to work on a rather unpleasant dissertation project and just got back to the bike. In what may well be a new record, I managed to mangle everything within about 30 minutes. I got in touch with Robert Barr O-ring guru - dude's got to be some sort of saint or something. Anyway, I figured it was time to replace all the O-rings. I started by popping off the tank and cleaned 'er out a bit just to build confidence. As it turns out...building confidence on an easy task is a terrible idea - as it turned out my lack of confidence was based on a real lack skill. I got a bit rash and started unscrewing (or perhaps more accurately screwing) everything in sight. The end result is a lot of loose hose clamps, a loose airbox, and a egg carton full of little bolts. Unfortunately, the carbs feel like they're still locked in there pretty tight.
This leads to the wonderfully embarrassing question. I've got the guide for cleaning out carbs from the site here, how in the ruffle-fire do I get the blessed things off my bike to begin with? Is it just a deal where you loosen up the hose clamps and give'r a good yank?
I realize this should be obvious, but...well, I was the guy who called the what's-it the other what's-it...
Simple advice using tiny little words would be most appreciated.

Warm Regards,

[BassCliff]

Greetings and Salutations!!

Hi Mr. Rudi,

I don't think I've had the pleasure of giving you my soon-to-be-patented "mega-welcome". In it you will find a couple of maintenance lists with tasks that are, for the most part, mandatory in order to get your classic GS restored to its original, reliable, safe, bullet-proof condition. Let's get started.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Rudi]

Fine man...

Monsieur Basscliff,
Spectacular! A quick glance looks like I'll have some good reading for breaks over the next few days. Many thanks.

[cowboyup3371]

I've got the guide for cleaning out carbs from the site here, how in the ruffle-fire do I get the blessed things off my bike to begin with? Is it just a deal where you loosen up the hose clamps and give'r a good yank?

Rudi,
I just had to take mine back off this weekend and yes, just loosen up the clamps, move the airbox out of the way if necessary, and work it out. They'll slide out after a few minutes of decent tugging/wiggling.

[Rudi]

Poorer, and none the better

Well my friends, I borrowed a local expert and have managed to understand (though perhaps not fix) most of the bike from the air intake through the o-rings where the fuel-air mixture enters the cylinders. The carbs are clean and the "expert" got the full set of o-rings installed. So now, the bike just plain doesn't want to run.
It runs rough as everything and spits gas out of the air box vent hose. it won't settle into an idle and, after running for a bit, it doesn't want to start at all.
I'm a bit concerned because the jet for the carb on the 2nd cylinder appears to be frozen up about three-turns too far out...its seized up pretty tight and I'm not sure how to proceed with it. (Right now, everything is reassembled and I doubt everything stems from this single problem, but I could certainly be wrong.) Notably, the bike was spitting gas out of the air box vent prior to any work on the carbs.
Also of note, the expert charged $200 so I'm going to be making a mess of this by myself from here on out - $200 more for a bike that runs worse than it did before does not impress my extremely tolerant wife. Any advice or guidance would be spectacular.
Regards,

[BassCliff]

Hi,

Just go through the maintenance lists in your "mega-welcome", starting with The Carb Cleanup Series. That's how it should be done.


Thank you for your indulgence,

BassCliff

[Nessism]

Also of note, the expert charged $200 so I'm going to be making a mess of this by myself from here on out - $200 more for a bike that runs worse than it did before does not impress my extremely tolerant wife. Any advice or guidance would be spectacular.
Regards,

You are learning the hard way why people here strongly recommend performing your own maintenance. Only advice I can offer is to learn to work on the bike yourself before you wind up broke and divorced.

[Rudi]

Nessism - After ten years of colossal stupidity, I'm quite confident that a few more dumb ideas won't threaten the marriage. My bigger concern is trying to keep up a rough impression that I am not quite as incompetent as I actually am...one can dream.

BassCliff - I am a beggar and not a particularly swift one at that, so I have no business being choosy. At the same time, I'm quite interested in some sort of diagnostics. I believe that the problem may eventually get fixed if I piece by piece replace the entire bike; however, if a motor guru happens to know that a petcock, excessive vacuum, jet problems, etc. are the general cause of my motorcycle spitting gas out its air box vent hose it would be immensely helpful. I certainly like the idea of working my way through, but I am wondering a bit if I might sink months and dollars into a disaster bike that has some fatal flaw. (As an example, the grand welcome suggests that brakes and brakelines be changed, but I'd like to ensure that there is hope for the bike before I do this.)

Whatever the case, thanks for the responses...barring some clear, cheap fix suggested by you motorcycle gods, the bikes going away for a few months and we'll see what happens in the spring. Sincerest thanks for all the help...I'll spend awhile browsing the forum and see if I can learn anything.

[Nessism]

When the airbox fills up with fuel it's because the floats are not stopping the gas and the carbs overflow. This typically happens because the carbs are not clean and/or rust in the gas tank is holding the float needle open. One other possibility is because the petcock is leaking fuel down the vacuum line and into the carbs that way. Also, make sure you petcock is set to "run" and not "prime".

Again, it's best to learn to fix the bike yourself instead of paying someone to mess it up for you.

[Rudi]

Nessism-
Thanks for the heads up on the possible causes of the gas overflow... I'm afraid it is likely floats, but at least I can take a peek at the petcock. As for ponying up and making mistakes myself - your point is well taken...I'm a bit of a low slearner, but $200 bucks is a son-of-an-incentive to put me back on the straight and narrow. Again, many thanks.