My 92 GS won't start

[justinmc84]

First off, thanks to all for offering such great help.  I've lurked for awhile and am now posting because I'm at the end of my rope.  I've done a billion searches and am not sure what's going on with my bike.  92 GS, about 8000 miles.  Stock exhaust, lunchbox intake, rejetted.  Everything else is either stock or minor cosmetic modifications.

I took it out recently on an attempt to ride it to work here in Denver since the weather finally broke for awhile.  It started then sputtered and stammered and died out.  I brought it back to my apartment complex and haven't been able to get it going since.  So far I've done the following in an attempt to get the bike running:

1. new scorpion battery
2. new plugs
3. cleaned carbs thoroughly
4. replaced damaged fuel lines

When I plopped in the new battery, still no start.  She chugs like she wants to turn over, all the electricals work, it just won't fire up.  I don't know what to do next.  I'm getting extremely frustrated and wanna get this puppy going.  Any ideas?  Also, anyone riding out in Denver/Boulder?  Thanks guys.

[jacob_ns]

How's the fuel? Is it the same fuel you stored over the winter?

[justinmc84]

I knew I was going to forget something.  Nope, I put new gas in it as well.

[NickyNumbers]

is it turning over or not?  If it isn't and the battery is good, test the starter. 

[DoD#i]

Describe more exactly what's happening - it IS turning over and not firing, or it IS NOT turning over (turning over means the motor is actually rotating, not that the engine is starting - firing indicates more of a actual start thing (or at least the occasional chuff) happening.

Without more exact description - assuming it's actually turning over, but not firing:
- drain out the fuel
Replace with fresh fuel. <edit> OK, you did that much, at least. Good.
Set petcock on prime and use the carb drains again until you see clean fuel.

Make sure Choke is on (and the rest of FINECC)

Try to start. If it starts, turn petcock back to On. If it dies again, you have vacuum petcock troubles. If it doesn't die again, you just had old gas troubles.
------------
The short and lazy approach to the above, that might work:

Set petcock on prime and use the carb drains until you see clean fuel.
Marvel at the crap that was in your carburetors.
Top up tank with fresh fuel.
Shoot the shortest possible squirt of starting fluid into the air filter.
Make sure Choke is on (and the rest of FINECC)

Try to start. If it starts, turn petcock back to On. If it dies again, you have vacuum petcock troubles. If it doesn't die again, you just had old gas troubles. Go out and ride the heck out of it and add more fresh gas.
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IF IT DOES NOT START - turn the petcock back to On anyway - leaving it on prime can cause a world of troubles when it's not running.

[justinmc84]

It's turning over, like it's half a second from starting.  I plugged another spark plug into the boot on the wire and set it against the engine and it looks like theres a very meager spark coming.  I would definitely not use the terms fat or blue to describe it.  It seems weak.  This makes me think it's an electrical/ignition issue, which I'm not too enthused about.

[Twism86]

It's turning over, like it's half a second from starting.  I plugged another spark plug into the boot on the wire and set it against the engine and it looks like theres a very meager spark coming.  I would definitely not use the terms fat or blue to describe it.  It seems weak.  This makes me think it's an electrical/ignition issue, which I'm not too enthused about.

Well at least you have something to work with... These engines are simple. Make sure your getting fuel, air, and spark and that its turning over well. Good luck!

[justinmc84]

Could this thread perhaps be an issue I'm facing?

http://gstwins.com/gsboard/index.php?topic=48920.0

Or is that something I should look into after testing the starter?  How do I test the starter anyway?  I bought a multimeter but I have about zero experience using the thing.

[justinmc84]

The starter relay clicks when I unhook the negative and try to start the bike, so it's not that.

[justinmc84]

I checked the resistance at the coils using the methodology found in this thread http://gstwins.com/gsboard/index.php?topic=19546.0 and I'm getting solid numbers there so it shouldn't be the coils. 

Primary winding
white and orange/white 5.1 ohms
black/yellow and orange/white 5.1 ohms
Secondary winding
white and spark plug wire 19k ohms
black/yellow and spark plug wire 19k ohms

Those are the stats I got.  Primary should be from 3-6 and secondary from 18k-30k.  Now that I know it's not coils, what's the next step?  Take the starter motor out?  How can I check to see if this thing works?  Starter clutch issues maybe?  Would bump starting the bike eliminate anything? 

I thought it was an electrical problem because it doesn't seem to be getting a solid spark but everything seems in order going to the coils.  I'm begging you guys, save me a trip to a shop and help me out.

[DoD#i]

If the coils are good but the spark is bad I'd go looking for poor ground (and/or power) connections.

The starter can't really be bad if it's turning the motor over, unless it's turning it over absurdly slowly. I trust you are charging the battery between attempts at starting it. You certainly could try bump starting as a way to eliminate the starter, but I rather doubt that's your problem from what has been said so far. It's hard to get it turning over very fast when bump starting unless you have a big hill, and if you do and it does not start, you'll be at the bottom of said hill with a dead bike.

You seem determined to make this out as en electrical problem...

BUT: Have you really nailed down good fuel flow? You say the spark is not fat and blue, but you have spark. Your overall symptoms (it was running, then it crapped out) still lean more towards No Gas - crap stuck in the carb jets. And if you have spark, gas, and air you should have some sort of running.

Try a sub-second shot of starting fluid (ether) into the air cleaner and see if it fires after that. Also, take a good whiff of the stuff coming out the exhaust. There is air coming out the exhaust? Put your hand over the end to feel for it while cranking, and smell your hand, which should smell of gasoline if it's getting in but not getting lit. If not getting strong airflow, perhaps you broke a valve?

In the electrical line the more expensive and annoyingly not testable at home short of "swap in a spare unit" would be the ignition control unit - I don't know if pickup coil problems would make weak spark or not. I think dead control unit usually presents as no spark at all, not weak spark.

Once you are positive you have air and fuel, go back to fighting electrical gremlins. Far-out possibilities (barring a right-side drop you have not mentioned) would be bad or mislocated pickup coils, so you have spark but not at the right time, or no spark, depending on how they are bad - but you say you have spark, even if you think you should have a better one.

[justinmc84]

I'm going to go ahead and take the carbs off again, double check them for any noticeable blocks, probably reclean them, and give it another go.  Once I put it back together I'll give it a few more cranks (after recharging the battery again) and smell the exhaust.

I'm open to anything and everything being wrong, sorry if I come off like I know what I'm talking about, because clearly I don't.  I'm trying to apply what little common sense I have and its still not working out.  I'll try those tips you mentioned and post again when I get everything reassembled.  Thanks fellas.

[DoD#i]

...you might want to actually try what has been suggested, before leaping into tearing the carbs off again.

If you give it a shot of starting fluid and it fires, cleaning the carbs again is probably the right next step. Especially if you don't smell gas coming out the exhaust.

If you give it a shot of starting fluid and it does not fire, there may be something altogether else wrong. The starting fluid is a diagnostic tool to help you direct your efforts, by providing (temporarily) the "fuel" part of the fuel-spark-air triangle.

[justinmc84]

It finally started!

I went through and double checked all the hoses.  Everything seemed fine.  I replaced my fuel filter and the hoses running fuel from the petcock to the carb.  Drained the float bowls, rehooked everything back up, filled her back up, and success.  I want to thank all you guys for the help, as this was driving me crazy.  I've got to adjust the idle and pilot air screws, and I think I'm having an issue with the throttle cable, but I'll post that on its own.

A million times thank you!