OK guys.... I've posted about this before but I wanted to update you on my so called progress and see what our collective brain can come up with. 

I have lost my left cylinder (not missing in limbo... just wont fire).  Here is the entire puzzle to explain everything that could happen to possibly cause this.

Once upon a time a long time ago.... I was a stupid squid and knew nothing about bikes... ABSOLUTELY NOTHING.  To make a long story short... i thought i had an oil leak and didn't... i kept adding oil (dont laugh... i didn't  know and it was a long time ago) until 5-6 quarts later I DID have an oil leak.... EVERYWHERE.  I read some books... learned some and moved into fixing my bike (that i had only had for a month)  The bike still ran... but leaked oil everywhere and developped a loud tick that may or may not have been the cam chain tensioner or cam float.

I replaced all of the gaskets (head, cylinder, oil pan, generator, etc) and went to put the head back on....

Then I bent the valves cause I didn't know you had to put tigten the exhuast cam so that one of the valves was down (engaged).  (I was 3 teeth off... doh!)

I bought another bike and learned from my mistakes.

In the mean time i left the old one  in the rain uncovered for some time...

THen I (in list form)

-rebuilt the head (new valves and seals... but DID NOT LAP THE VALVES)
-Found that my left cylinder fouled after some long riding.
-installed a K&N pod and a rejet (127.5 and 40...1 washer... already had a slip on)
-after some time found that the left cylinder fouled after short rides
-replaced the cdi box (used)
-replaced the coils (used)
-after some time (a while after this attempt) discovered that teh left cylinder would not fire at all... no firing at all...
-replaced the signal generator (used)
-replaced the wire harness (used)
-rebuilt and cleaned the carbs including emulsion tubes (all new o-rings accept the one under the emulsion tubes and the left needle and valve)
-checked the float height via the kerry test (checked out fine)
-balanced the carbs
-switched the coils (no response)
-took up smoking (cigarettes)

There has been no response to any of these fixes... as you can tell I've spent a whole lot of time and money into fixing this bike.  Here are my only two options I can think of... tell me what you think or if there might be something I'm missing...

1.  The new found sealing power from a rebuilt head brought to life a compression leak in the piston rings (need new rings)
2.  Not lapping the valves  hindered them from sealing properly thereby leaking and not allowing the left cylinder to fire. 
3.  My intake valves are tight but not that bad... i hightly doubt this to be the cause... but its possible i guess
4.  My bike hates me and wants me to cry.....

Any help would be appreciated!

okay, I've found the problem, and its totally simple.



your left cylinder doesn't fire.



have you replaced your Spark Plugs?  are they gapped properly?.... (stupid questions I know)

no help is stupid help.... but yeah.. i've ben through like 12 sets... i've used the ngk 4929's and the champions and checked the gap like 1000 times... i wish it were that

I would be interested in the resistance values you get as you fill out the checklist in this old post.  Feel free to read the whole torturous thread for more background on my own "bad left cylinder" saga, which lasted 5 months.... 

i know that you have probly done this but have you pulled out the plug and held it up to the engine to make sure it is actually sparking. don't hold onto it unless you really want to learn why, the hard way

If it helps, I was always able to get a spark against the engine from the left spark plug.  But the cylinder still wouldn't fire - or fired "weakly" with a weird rythym and sent a lot of unburned fuel out the exhaust pipe.

It wasn't until I made my way through the wiring diagram with an ohmmeter that I found the problem.  In my case it was a corroded connector -- in this case it sounds like a missing connection somewhere.

Do you have compression on the left cylinder?  If so, you know the rings and valves aren't the problem.  You can borrow a compression tester from auto parts stores if you don't have one.

-M

I've used a compression tester... i'm getting around 135 on each cylinder.. this is lower... but not abnormal for such and old bike..... this is why i'm puzzled....

HEY.... ESPECIALLY KERRY.... COULD THE REGULATOR do this?

when you said you had the head rebeilt did you use the old pistons and rings i'm guessing ? .. you had the head off if it where me i would have shiped it off and had it bored and ported  but thats me .. you might havewanted to buy new pistons and rings to use in there .......

Quote from: KYGS500E on May 23, 2006, 02:42:23 PM
I've used a compression tester... i'm getting around 135 on each cylinder.. this is lower... but not abnormal for such and old bike..... this is why i'm puzzled....

HEY.... ESPECIALLY KERRY.... COULD THE REGULATOR do this?

That's perfectly healthy, so your top end is not the problem.  It's gotta be electrical.  Work through the flowchart that Kerry posted and see what you come up with.  Sorry it's been such a pita, I hate electrical gremlins.

-M

Quote from: KYGS500E on May 23, 2006, 02:42:23 PMCOULD THE REGULATOR do this?

Good question!  I didn't have to get into the regulator for my fix, so I haven't done much in the way of regulator research.  But in my "stack o' stuff" I have some scans from the Haynes manual that will give you the expected resistance values.  Hang on....

Ah - here it is: 

Regulator/rectifier unit - check and replacement[/list]

It's probably not related, but along with that I included some other "charging system" info in this old thread.

Are John Bates and starwalt still active on the forum?  They were pretty good at electrical stuff....

 My disclaimer:  I do not own a GS.  Most of my bike workings come from my old CBs.  I will assume your bike has breaker ignition?

To run, a bike needs;
Air & Fuel
Compression
Spark

Air/Fuel you took care of with the rebuild.  Just to be sure, you could pull the exhaust off,  disable the ignition, and put a piece of paper in front of the exhaust ports.  Crank it over. They should both get equally damp with the atomized fuel, indicating your carbs are working.

Compression:  You tested.  135 psi is fine.

Spark.  The worst of the 3.  First, the obvious:  Swap the coils left to right.  If the left cylinder starts working, you know your coils buggered.  If not, continue.  Check for 12V at the coil with key on.  Without the electrical diagrams, I can't tell you the colours, but there's only two wires and ONE should be hot with the key in RUN (12V positive). If neither is 12V+ with key in RUN, that's the problem.  The other wire is the ground side, which SHOULD be grounded.  If it is not, turn the motor over 90 degrees and check again (points could be open).  If still no, that's your problem.  Assuming you have 12V constant and Ground pulsed (from the breakers) you will have spark.  It might not be at the right time though.

Question:  How do you know your left side isn't firing?  Exhaust pipe cold?

regulator should have nothing to do with your problem.

12.5 V at the batt?
13.6-13.8V when running?
are you getting spark? on the left
is the left float stuck shut?
fuel in the bowl?

i.... did you paint the frame?

ok.... I'm going to try to get my hands on a multimeter soon ( have a friend with a good one).  My floats are opporating fine cause i tested the levels via float height check.  If it makes any difference I too had intermitten and weak spark at one time (a bit ago) before the cylinder stopped firing altogether.  I assume this because the cylinder is cold even after a long period of running and the plug is just wet and no color change (metal color only... not white or black... or tan)

Thank you all for yoru help... I'll post again when I get my multimeter

hey kerry... what connection was bad for you and caused this problem?

I'll read the write up right now... just chekcing ... its forever long

I think it was the cigarettes.  Seriously, why would you take it up all of a sudden? 

The things that caught my eye were:

-rebuilt and cleaned the carbs including emulsion tubes (all new o-rings accept the one under the emulsion tubes and the left needle and valve)

It's your left cylinder that's giving you trouble, right?

-took up smoking (cigarettes)

*Slap*

1.  The new found sealing power from a rebuilt head brought to life a compression leak in the piston rings (need new rings)
2.  Not lapping the valves  hindered them from sealing properly thereby leaking and not allowing the left cylinder to fire. 

Do a leakdown test to see if one of these could be the problem.

3.  My intake valves are tight but not that bad... i hightly doubt this to be the cause... but its possible i guess

Adjust your valves.  It's not that expensive.  Shims are $10 from the stealer, less from aftermarket.

nice to see Kerry back...

Good luck with the cylinder.

Quote from: Noltz on May 23, 2006, 04:12:04 PM
..........................................................
Check for 12V at the coil with key on.  Without the electrical diagrams, I can't tell you the colours, but there's only two wires and ONE should be hot with the key in RUN (12V positive).

The 12V wire is orange/white.  Also put transmission in neutral and engine stop switch in ON position.

Quote from: Noltz on May 23, 2006, 04:12:04 PM
The other wire is the ground side, which SHOULD be grounded.  If it is not, turn the motor over 90 degrees and check again (points could be open).  If still no, that's your problem.  Assuming you have 12V constant and Ground pulsed (from the breakers) you will have spark.  It might not be at the right time though.
.......

The ignition system is transistorized.

Quote from: KYGS500E on May 23, 2006, 08:11:51 PM
hey kerry... what connection was bad for you and caused this problem?

I'll read the write up right now... just chekcing ... its forever long

How's the "wading" coming?    I just now went back through the thread, and almost everything you need is on page 3.  Two posts up from the checklist that I linked to is a photo.  It shows the 4-wire connector that had a SINGLE bad connection ... and the set of separate "quick connectors" that I eventually replaced it with.

Unless you've been trying to clean your battery terminals with a baking soda solution while it's still in the bike ( ), you probably won't have the exact same problem I did.  But I bet the problem IS electrical, and that it is somewhere between the connectors I describe on that 3rd page and the signal generators ... which are behind the right-side engine case cover.  Taking the readings to fill out the checklist should handily prove or disprove that theory.

Hey Kerry... i have to say i'm impressed that you returned for my post....

Just to let EVERYONE know... the smoking thing was just a joke.... i think its a nasty habit!  Plus... i'd get fired if i smoked (clergy...lol).

Anyways... I'm all over that check list.  I'll be checking the wires really soon (as soon as I get my hands on a multi meter.)

WHAT DO YOU THINK ABOUT THIS THOUGH...

Since i did replace the wire harness with another one and there was NO change in the condition... I would assume that it has to be outside of the harness (i.e. an external part like the cdi box, signal generator, etc).  My confusion is that I have replaced all of these as well with no luck...

New signal generator (pulse generator)
New CDI Box
New coils (actually all these parts are used which isn't perfect....but makes it unliekly that they are bad)

The only ones i haven't replaced are as follows:

Kickstand switch wire (possible???)
Oil pressure wire (possible???)
Rectifier/regulator (possible???)
clutch switch wire (posible???)

I'm going to look at that diagram (which thanks to kerry has been on my computer for some time now) and see if these could relate... I'm not sure.... lemme know what you think