Some things to add to the thinking process below.
The frustrating thing so far is that none of the readings seem to indicate a clear fault of the stator.  Typically "sounds like your stator, do the tests" results in "yep, found a short between ..... and ....."


I might add that when you are reading the resistance of the various coils of the stator what you have is a length of copper wire from the plug at CDI or R/R, to the actual coil(s), through the length of the coil of a certain thickness winding, and then back via the other wire.  Different types of wires used and joined at the coils because the type of insulation and the stranded wire that are good for the harness are not good for windings and vice versa, otherwise you can just think of the harness and coil as a big loop.  If the reading is extremely low it typically means a short in the layers of the windings or even the wires have touched some distance away from the winding.  A high reading can mean fraying in the wires causing a poor circuit.  An open reading of course means something broke completely.  A reading of any value from one coil to another or to the engine case means either insulation on the wires or insulation on the windings has failed and is letting them contact.  Winding insulation failure is usually heat related or mechanical damage from bolts backing out of the starter clutch or one of the 3 stator bolts coming out.

If the insulation failure is minimal it may only show up at higher voltages than the meter uses (edit:  referring to the internal battery or batteries of the meter which are used as the power source for resistance checks) such as when the charge coils are excited when the engine turns over.
If a charge coil winding is shorted to the stator frame, and the signal coil is shorting or has weak insulation to the charge windings then a voltage induced in the charge coil can make a path of: case-->charge winding-->broken insulation to signal coil-->signal coil lead to CDI--> CDI internal circuitry back to ground at engine.  That is what causes the problem, and in this example because of the short to the stator frame unplugging the 3-yellow-wire harness will not "fix" it.  If there is a short between the signal coil and charge winding BUT no short to the stator frame then unplugging removes the path to ground via the R/R and that is why it will run.

You can get an idea of the winding just from the specs for it.   The trigger coil is a long length of thin winding.  This is why it also has a higher peak voltage.

The signal coil is a short length of thicker winding, thus it has a very low resistance.  It is basically a 2 foot piece of about 24g wire.  Such a short winding generates a fairly small peak voltage.

The charge coils are each wrapped as a single wire that runs on every 3rd post around the stator frame so that when these are all excited by multiple magnet poles in the flywheel the series effect of these windings makes a higher voltage.  Thickness of winding is to allow for current flow without overheating.  Total of 3 such windings connected in a star mean that when metering actually 2 coils are being measured in series.




I remember one person that had a sporadic problem for a bit, presumably as it was just starting to fail.  Heat seemed to affect the problem, although his would start.

One person had the chain wear through the harness where it goes over the front sprocket because the case protector was missing.  The problem showed up as cutting out at higher speeds when the chain would contact the wire.


So you need fuel, compression, and spark at the right time.

Fuel  --> present and burnable based on header warming

Compression -->  not confirmed, BUT:  valve clearances checked and ok.  engine ran for 20 seconds after starting with electric starter. No 'bad noises' have been mentioned.  Attempting to pop start should verify this is not the problem.  Was the valve timing confirmed?  What type of CamChainTensioner?(manual or auto).  When valves clearance was checked no mention of a loose timing chain was made.   How hard is bike to pull backwards in gear as this prevents the decompression from activating.  Should be almost impossible to pull backwards in 1st (by hand of course)

Spark at right time -->  Spark is present.  Fuel mixture has ignited and warmed exhaust but won't run.  Symptoms match previous examples of spark NOT at right time.  Stator appears to pass electrical tests though.  NO physical inspection of stator yet though.

Edited by slowriding, 14 May 2012 - 10:18 PM.

Last comment for now

To clarify taking small resistance readings.  Touch the leads of the meter.  Note reading.  For this example I am going to say leads touching says 0.34 ohms.  Note that many meters are not accurate below tenths of ohms.

Take the reading on what you wish to check.  For this example I will say the reading is 0.45ohms

Subtract the reading of leads touching from the measured resistance.  
0.45
0.34 -
======
0.11 ohms actual reading

do the measurements a couple times to ensure they are repeatable.  Again, very small resistance values are hard or impossible to read accurately with a standard DVOM even if it is good quality.  There are special ways of measuring these small  values.

The reason this is pertinent is the POSSIBILITY exists that side-by-side wraps of the signal coil have shorted and the actual value is lower than is being read.  A peak voltage reading WILL be valuable at this point.  Some cheap meters have the peak function and some good ones don't.

If the signal coil passes the peak voltage test AND is not shorted to ANY other part of the stator it should be fine.

Edited by slowriding, 12 May 2012 - 10:33 AM.

Back again,  I bought a compression tester and did a quick check ,  Only made 50psi while cranking with the starter.  I put some oil down the spark plug hole and tried again, this time  90 psi and the starter seemed to kick out at 90psi.and free wheel.   What is normal psi ?    Before I tear the motor apart , Could the rings have been washed by gas from trying to start it?

This motor never smoked back when it was running but it always seemed to run a bit rich and didn't need much choke starting.  The plug was a bit on the black side but not overly oily .  Motor turns over fine and never made any noises before it stopped.

Thanks again

watertreatpete, on 13 May 2012 - 03:13 PM, said:

Ideal is 166.1 and low acceptable is 135. =(

Edit: 166.1 is unconfirmed.

135 is out of the service manual.

Edited by AKW89, 13 May 2012 - 05:39 PM.

Suzuki service manual says 135 with the decompression activated.  I have not conformed that and frankly seems unlikely.  It is possible to take the top motor cover off and deactivate the compression release  by wedging the fly weight out with a piece of nylon wire tie.  I have not tried that either but seems doable.

Although odd, there are documented cases where the rings stick in the ring grooves and compression disappears almost instantly.  Runs when parked and refuses to start the next day.  When you checked the valve clearances, were any of the clearances unusually large?  Like a valve not closing all the way?

The best test to do now is a cylinder leak down test.  That will tell you how much leakage and where the leak is.  Even if you don't use a calibrated tester, just air pressure in the cylinder with valves closed will tell where the air goes.

The exhaust valves both were at the extreme  , I will have to check my notes but I think they were .305   I know .30 is the high end but figured it was Ok.   , The intake side they were at the far end  too like .19 or so .  I am the third owner of the bike and it has only 8 or 9 thousand on the clock if its right.

Valve clearances are meaningful if you know what they were before and they are greater now.  Otherwise, probably not significant.

As the valves wear the clearance gets smaller.  The valve face starts to wear and lets the valve move farther into the head, so the stem is closer to the cam.

I wonder if an earlier owner shimmed it to the large side to 'give it room to wear'.  I have made that mistake before I realized 'wear' basically equals 'failing' on a bike valve face.   These are thin hardened valve faces, not big thick car valves.

-------------

We had a PT Cruiser get towed in at the shop that the owner had timed the cams wrong when he changed the timing belt.  I guess he cranked and cranked trying to get it started.  I corrected the cam timing but it would still not start so we assumed bent valves as it is an interference engine.  I removed the head but all the valves looked fine and didn't leak with alcohol in the ports.  At that point one other mechanic said he had seen something like that one time before where the gas had washed down the rings.   We oiled around the pistons and put it back together.  It ran.

The difference I see with the bike is it was running when it quit.   Most of us have flooded our bikes when they keep running lying on the ground after we wipe out.  Holding the throttle wide open and cranking usually clears it.

It is even possible there are 2 problems now, the stator and the low compression from oil wash down from trying to start it.  Any luck on the peak voltage test for the signal coil?  There have been ones that failed in that way before.  No short to other parts but very low peak voltage.

If it is only low compression it should start by push starting.  Coast down a hill and in second gear let the clutch out.

--------------


How much oil did you put down?  If the starter torque limiting clutch slipped it might have been coming close to hydrolocking.

YOU SHOULD MAKE SURE THIS IS NOT THE CASE BEFORE ATTEMPTING A PUSH/POP/BOMB START (whatever you want to call it)


-----------------

Correct me if I am wrong but I believe Noble means something like an extra 0.003 or even much more which could be a bent valve.

Edited by slowriding, 13 May 2012 - 11:11 PM.

anything sound familiar?  This had low compression but was causing running issues and had not just started 20 seconds ago

http://www.thumperta...will-not-start/

I don't think this has been asked yet.  Since it stalled as it was warming up, you don't have gas in the oil do you?  If the oil smells of gas this could have been the start of it stalling and the rings washing.

Slow - Yes, bent valve or even just something stuck underneath one or some problem with the spring retainer

slowriding, on 13 May 2012 - 11:38 PM, said:

my thread is a lonnnnng read, given what the OP has stated so far, I'll summarize it:

noble posted it needs a compression test with the zip tie/something to disable the auto-decomp, and if it's definitive, a leak down test.

i also suspected the stator. i was wrong. i had a very similar circumstance to what the OP has stated. as odd as it was, the rings were simply frozen in the pistons grooves, and worn out. i'm not saying that is the case here, but it sounds very famiiliar/similar.

do a compression test with auto-decompression disabled, and then a leak down. i think you'll find the valves are fine and the rings are shot.

post up if/when a real answer is found, please.

***edited***

watertreatpete -

also, there are some decent  pictures and videos of things in that thread, which I'll copy/paste here for convenience. engine not starting, very low compression with decent sound for you to compare yours to:


and the zip-tie in the decomp mechanism:





blue circle= valve bucket face
red circle= decomp pin (rotates)
yellow circle= zip tie end jammed into auto-decomp mechanism to allow compression testing

hope this helps. :-)

Edited by ohgood, 14 May 2012 - 12:09 PM.

Ok  I dug in to the motor , Found that the top two piston rings were stuck.  I guess the piston got hot., even though it looks brand new. The end gap on the ring looked small to me, will have to check it.


  Not sure if it was caused by me not rejeting after adding an rs-2 and 3x3 air box mod.  or  one of my radiators is a bit bent. The fan seldom comes on and the temp light never came on.

   I ordered a new piston and rings.  

thanks for the help

watertreatpete, on 05 June 2012 - 08:37 AM, said:

according to the diesel heads i talked to:

incorrect jetting (HOT piston) + a splash of gas (flooded bike) = stuck rings

doesn't happen all the time obviously, but can happen. make sure you jet properly when you get it back together.

Edited by ohgood, 05 June 2012 - 10:27 AM.

Watertreatpeat - I would be interested to know what you find for ring end gap both with the old rings and the new rings.  Suzuki specifies a very small ring end gap.  .003 to .008 inches.  Seems odd, just curious what you find.

Ring end gap was ok.  Your right it is very small  I think new it is .003 mm or something.  I got a new piston and rings.  i will use them when putting it back together. The end gap for the new top ring was 0.010mm.  
  I managed to free the old rings with a pick. They looked to be stuck from carbon in the grove.  It took a bit of effort to free the top ring.  After freeing the rings they seem to fit back in the groves fine, but seem to have lost a bit of spring in them anyway. I guess I'll scrap the old piston and rings.  It is strange how the bike ran one minute and the next it wouldn't.  Hope it doesn't happen again.