New to site and the GS! (Need help)

[Kalaazar]

Hello all!  I have been reading and trying to scour as much info as I could before posting a "I need helllllp!" thread.  BUT.....

{NO SPARK IN LEFT CYLINDER}

Quick backstory:
My name is AJ.
I bought my Sister's (Fancy Purple) '92 GS500 (she was umpteenth owner) for my wife.
It has almost 20k miles.
It ran pretty good for the last few years of my ownership...  until this year!
I maintain it myself and 'winterized' it with Sta-bil and trickle charger & whatnot.  (I live in Pacific Northwest so it gets started &/or ridden monthly.)

Problem:
Earlier this week, I fired it up so my wife could practice this coming weekend.  Battery was low on acid so topped it off with distilled.  (pretty sure its dead, no biggy I bought it in '03.)
After jumping it, it was running well.  Then the left cylinder died.  If I revved the crap out of her, it would pop.  I figured it finally got the carbs all gunked up so thought that I might be able to BLOW THEM OUT with a spirited ride.  Added some carb cleaner and rode it freeway style.  Only the right cylinder was working for 90% of the time, then some crazy 'backfiring' was occurring.

Brought her home and cleaned out the carbs.  EWWWWWW, were they filthy!!!  All clean now and no problems inside.
Still only runs on right cylinder.
NO SPARK IN LEFT CYLINDER!
I have tested everything my Clymer book tells me to test, everything tests ok.  Everything is within spec.
Swapped plugs, no luck. 

I need ideas pretty please!!!  Don't feel like taking her to the dealer for a random electrical gremlin at $89 an hour....


Thank you,
~AJ

[Paulcet]

I don't remember if the Clymer book has a procedure for the crank position sensors.... Any way, the have been reports of heat related pick-up failures.

[J_Walker]

Ouch.. are you sure its not getting spark, I know you said you checked, but are you SURE? At first I thought that same thing, turned out it wasn't anything to do with spark. and as I dug deeper, it was the valves being to tight. luckily I never bent a valve stem.

when was the last time you checked your valves? I hope its been at lease once at 20k miles.. cause good lord, I don't see how you could not have checked them in 20k miles as mine gave up around 12k

[BaltimoreGS]

Swap the coils side to side and see if the problem switches sides.

-Jessie

[mister]

Check the leads too. Sometimes the plug isn't in them right, sometimes they need replacing.

Back in the day a service on a car meant... change the plugs, points and leads.

Michael

[step]

Not sure how our bikes will act, but I have seen some goofy-ass behavior on other bikes show up from bad batteries.   You might want to get it load tested if the coil swap test doesn;t tell you something.  Good Luck.

[Kalaazar]

First of all, thank you to all trying to help me!  I appreciate it.

@ Paulcet - I have not checked the crank position sensor.  Could that cause a lack of spark in one cylinder?  Would that require a lower end disassembly?  Having trouble finding it in the book...

@J_Walker - I am sure that I do not see a spark.  I have not attempted to hold it while cranking it to be SURE, but in a darkened garage, there is no visable spark.  Question for you though, how could the valves being too tight cause a no spark issue?
Valves have been serviced within 8k miles - they are due for some checking for sure...

@BaltimoreGS - I looked at swapping coils side to side, but they appear directional.  I don't have enough hands atm to hold them while attempting to start it.  (Not too willing to ask the kids to hold em either! LOL)

@mister - Leads?  Do you mean the spark plug wires themselves?  I checked resistance on them and they are within spec. 

@step - I have had it running on its current battery and/or while jumped to my truck.  I wish it would be that easy.  New battery is needed though, any thoughts on one??

I have checked the following per the Clymer book of wisdom:
Voltage Regulator Test - OK
Stator Coil Continuity Test - OK
Ignition Coil resistance Tests - OK
Signal Generator Coil Test - OK

All tested within the given spec.

So what other ideas do we have on what could be causing a single cylinder lack of spark???

The only thing I cannot check is the Igniter Unit...  which has me worried at this point!  I suppose I might need to check continuity between the wires to/from Igniter and Coils.

Thanks,
AJ

[BaltimoreGS]

The coils are interchangeable side to side.  Just 2 bolts holding each one on, be careful not to lose the spacers.  I would swap them and see if the problem switches sides.  If so, hit up Adidasguy for a good used coil   

-Jessie

[Paulcet]

Sorry.  Signal generator is what I was talking about.

[adidasguy]

The coils are interchangeable side to side.  Just 2 bolts holding each one on, be careful not to lose the spacers.  I would swap them and see if the problem switches sides.  If so, hit up Adidasguy for a good used coil   

-Jessie

I got a pile of coils.
The signal pickup on the lower right side: like Paulcet mentioned, you have 2 pickups on your mode. If one is bad or the connection is bad, you'd lose one spark. You can trace the wires to be sure all is connected. (You can't swap these since one is for left side and one for right). Don't remove them, just check all the wiring for bad spots or dirty connection.

Also unplug and plug back in your ignitor box in case there is a dirty contact. That's a rectangular black box on the left side under the seat, opposite the voltage regulator. It has a couple connectors on it.

[Kalaazar]

Thanks again to everybody that helped on this!

Long story short, it is now fixed.

It was a broken wire midway through the harness from the signal generator...

Fixed and running like a champ!  The cleaned carbs and the single washer on the jet trick really seemed to make a difference!!

[Kijona]

Ouch.. are you sure its not getting spark, I know you said you checked, but are you SURE? At first I thought that same thing, turned out it wasn't anything to do with spark. and as I dug deeper, it was the valves being to tight. luckily I never bent a valve stem.

when was the last time you checked your valves? I hope its been at lease once at 20k miles.. cause good lord, I don't see how you could not have checked them in 20k miles as mine gave up around 12k

Listen and learn, young sprout. Shim and bucket type valve actuators are notorious for holding their adjustments for long periods of time after the initial break-in. The valves on my V-Strom (that's another Suzuki bike), were adjusted at around 7,500 miles. 6 years and almost 30,000 miles later, they were still within spec, and had a long way to go before being too tight. A friend from another forum reported going almost 50,000 miles without needing to adjust the valves.

[Kijona]

Thanks again to everybody that helped on this!

Long story short, it is now fixed.

It was a broken wire midway through the harness from the signal generator...

Fixed and running like a champ!  The cleaned carbs and the single washer on the jet trick really seemed to make a difference!!

Glad to hear you got it all working again there Kalaazar. Too bad you didn't have a set of upgrade jets laying around to put in (yes even a completely stock bike benefits from being rejetted). Oh well, another project for another day, eh?