No signs of life.

[youstolemybeer]

1980 gs1000g.

Ive used the search function and sofar have found nothing about this problem. It only starts with my hand over the carb inlet and the choke on, and runs for about 10 seconds then dies. Ive gone thru the carbs, checked the valve clearance (thanks BikecCliff) checked spark.
It has to spin for quite a bit before is sputters (with my hand over the carb throat) then it will eventually start, and then immediatly die. It dies when no matter if my hand is over the carbs or not.
Any Ideas?
Thanks
steve

[Calvin Blackmore]

Attach your airbox and filter

[Steve314159]

Did you check your intake manifold/boot o-rings where the rubber boots attach to the head? Common problem. If they are old you get a major air leak and not enough fuel.

[Griffin]

Attach your airbox and filter

Yeah....what he said.

[azr]

Fuel, air, or spark as is always said. Was the bike running before? did you check to make sure your petcock is functioning? what does the spark look like on the plugs?

[BassCliff]

Greetings and Salutations!!

Hi Mr. youstolemybeer,

These bikes hate running without their airbox. You can double a shop rag and zip tie it around the carb intakes as a temporary measure just to get it running. But for serious tuning and maintenance you'll need to seal your total air intake system; airbox (use weatherstripping), airbox to carb boots (replace), carb to head boots (replace), intake boot O-rings (replace), etc. It's all in your mega-welcome.

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

[youstolemybeer]

with the air box on it does the same thing. the carb boot o-rings are good. (for good measure I sealed them with spay permatex). Carb boots are nice and soft, not cracks or chunks(checked by looking at them with a magnifing glass) The fuel petcock is good.
On thing I noticed was that when I would cover the carb/carbs, large amounts of gas would pour out the carb throat. I verified the carb float height, all with in spec.
Thanks for everything sofar.
Steve

[bwringer]

Then it's time to COMPLETELY disassemble and clean the carbs the RIGHT way and install new O-rings.

You have blockages in the wee hidden passages in your carbs.

It ain't hard at all. Really.

We even have an illustrated step by step guide.

No shortcuts. You can't fix this with spray cleaner.

[old_chopper]

Second what Bwringer said.

[Nessism]

with the air box on it does the same thing. the carb boot o-rings are good. (for good measure I sealed them with spay permatex). Carb boots are nice and soft, not cracks or chunks(checked by looking at them with a magnifing glass) The fuel petcock is good.
On thing I noticed was that when I would cover the carb/carbs, large amounts of gas would pour out the carb throat. I verified the carb float height, all with in spec.
Thanks for everything sofar.
Steve

You convicted yourself with the "permatex" remark. And how do you cover the carbs when the airbox is on?

[youstolemybeer]

the permatex is on the o ring side of the carb boots. NONE is in the carbs. the bike was sorta running before i got it. Im gonna go out now and soak them with Seafom and carb cleaner. and use the wire brush trick, as well as get new o-rings
wish me luck
steve

[BassCliff]

Hi,

To quote part of your "mega-welcome".....

***********Quoted from Mr. bwringer************
Every GS850 [and most other models] has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.

What I have noticed at the rallies is that very, very few 850Gs are actually running right. Make VERY sure it's actually running the way it's supposed to before busting out the modifications.

Brian's E-Z and fun plan for GS850 happiness:

1) Seal the airbox and air filter with weatherstripping.

2) Ensure no intake leaks. Spraying WD-40 or water doesn't tell you much, since very small air leaks can cause problems even though they won't suck in enough WD-40 to make a difference. Replace your intake boot o-rings and boots if needed, and seriously consider spending the lousy $28 for new airbox/carb boots.

3) Ensure clean carbs with correct settings, new o-rings, and original OEM jets. No, not just squirted with something. I mean completely disassembled.

4) Check/adjust valve clearances (Manual calls for every 4,000 miles. This is not optional.)

5) Ensure healthy electrical system.

6) Seriously consider upgrading coils and plug wires.

7) Install new, stock NGK B8-ES plugs gapped to .031".

8 ) Fine-tune float height and idle mixture screw to ensure best off-idle transition.

9) Clean air filter and reinstall with only the lightest oil mist -- over-oiling and/or letting the filter get dirty is a common and critical mistake, and will make the bike run funny at low speeds and run rich. This may take a few tries.

10) Make sure the exhaust seals are sealing.

11) Ooh, much better now, huh? You're gonna need upgraded suspension - Progressive or better fork springs and shocks. Set suspension sag appropriately.

12) Upgrade brakes with new pads and stainless lines to deal with all that extra speed.

13) Install new petcock, since I'm going to head to the roof with a rifle if I have to read about yet another #2 plug fouling and failed hillbilly attempts to rebuild the petcock and/or deny there's a problem.

14) Oh yeah -- check compression somewhere in there to ensure the valves and rings are reasonably healthy.

15) You'll probably need new OEM clutch springs -- the clutches last forever, but the springs get tired after 20 years or so under pressure. E-Z and cheap.

Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:

http://bwringer.com/gs/intakeorings.html

Here's an overview of what happens with this particular problem:

http://cycleorings.com/intake.html

You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm






Thank you for your indulgence,


BassCliff

[youstolemybeer]

ok, did the shop rag thing, it starts and runs now, sounds a rather rich (kerker 4to1 pipe and 115 jets). It starts from dead cold with only a bit of choke, another arrow pointing toward too rich. I will check the plugs in the morning.

O-rings, I want to make sure I am understood, I put the permatex spray on the O-ring and then into the carb boot, not just sprayed the boot. In regards to O-rings, Im thinking that the rings at the idle mixture screws are bad, my reasoning it that I sealed the idle mixture area with grease as a temp fix and it started up (scared the hell out of me).

Air box, what the hell, its a box with 4 big holes in it, how the heck can it have that much effect on the running of these bikes. Im half way smert when it comes to automobiles, aint never heard of a car not being able to run without an air cleaner.

THANK YOU ALL FOR YOUR HELP.

[Nessism]

ok, did the shop rag thing, it starts and runs now, sounds a rather rich (kerker 4to1 pipe and 115 jets). It starts from dead cold with only a bit of choke, another arrow pointing toward too rich. I will check the plugs in the morning.

O-rings, I want to make sure I am understood, I put the permatex spray on the O-ring and then into the carb boot, not just sprayed the boot. In regards to O-rings, Im thinking that the rings at the idle mixture screws are bad, my reasoning it that I sealed the idle mixture area with grease as a temp fix and it started up (scared the hell out of me).

Air box, what the hell, its a box with 4 big holes in it, how the heck can it have that much effect on the running of these bikes. Im half way smert when it comes to automobiles, aint never heard of a car not being able to run without an air cleaner.

THANK YOU ALL FOR YOUR HELP.

Please don't take this the wrong way but you're wasting time and energy thinking too much. Pull the carbs, tear them apart, soak them in carb dip and get a new O-ring kit from cycleorings.com. Install new O-rings on the carb boots and do NOT use anything on them other than maybe a dab of silicone grease to hold them in the groove of the carb boot when you install them.

Install the carbs and the airbox, make sure the airbox is full sealed with a fresh air filter installed (use weatherstrip foam on the airbox ends if the OE foam is deteriorated), and then you can start tuning. Of course this assume a clean gas tank and nothing added into the system that can disturb things such as a fuel filter. Fit new plugs and adjust the valves while you are at it and start doing plug chops to check mixture.

[Steve]

Air box, what the hell, its a box with 4 big holes in it, how the heck can it have that much effect on the running of these bikes. Im half way smert when it comes to automobiles, aint never heard of a car not being able to run without an air cleaner.

THANK YOU ALL FOR YOUR HELP.

That's because the bike carbs don't quite work the same way as car carbs.

If you are at all acquainted with the old four-barrel carbs on cars, do you know the difference between mechanical secondaries and vacuum secondaries?

If you understand how vacuum secondaries work on a car, let's see if we can twist your thinking a bit into the bike world.
The slide that is lifted by the diaphragm is essentially your secondary. Unlike the car, your primary breathes through the secondary. If you whack the primary open, the slide is still closed, keeping the velocity high through the small opening at the bottom. As the engine speeds up, more air is drawn past, the faster-flowing air has lower pressure than the surrounding air (basic physics, called the venturi principle). The hole in the bottom of the slide is open to the top of the diaphragm. The lower air pressure now lifts the slide, allowing more air through the carb, but only at a rate that keeps air flowing fast enough over the jets to ensure that gas in put into the air stream.

The stock airbox does several things beside filter the air. The opening is sized to provide a bit of restriction to enhance the vacuum that lifts the slides. The boots from the airbox to the carbs are actually rubber velocity stacks that help smoothe the air flow. If you change the restriction or the smoothness of the airflow, you will have to compensate in other ways, including re-jetting and/or enlarging the hole in the slide.

My personal belief is that, unless you are racing and need every last bit of power that you can squeeze out of the engine, the few extra ponies that you might get really don't make it worth it on the street. With all the jetting hassles, the extra noise, extra cost and extra maintenance, it's just not worth it to me.