Hello all,

Ok so here is the Bike

'06
GS500F
Yosh pipe
K & N Lunchbox
rejet (147.5 mains, 20 pilots)

Long story short:
Bike was running fine but died randomly with no hesitation, surging or otherwise on my way to work today, the first time after a few moments she re-fired, the second time on my way home today she died again, now won't start, turns over cleanly and almost want to fire, but wont fire. Yes it is full of gas, here is my list of possible problems:

-Valves (haven't been adjusted in two seasons  )
-Clutch Cable was "loose" at the handle, perhaps grinding the Clutch gear so it doesn't engage.
-Carbs, I belive they run rich at 2.5 turns out but, Honestly I haven't checked the plugs in a while

Also while trying to mess with it in the dark I noticed when the key is in the on position, (ready to start) I'm reading 500 RPM?? Never did that before and I assume it is related. Is it tied to the safety switch, because if in a gear and the kick stand is down it returns to 0 RPM's.

I Plan to get it moved tomorrow, and have the day off so will be checking the Plugs, Coil, wires, compression, valves, carbs, and all my grounds. Any other recommendations would be greatly appreciated!!

Here are some easy things:

EDIT: Adjust your clutch both major and minor.  Search the forums for the procedure, or check your maintenance manual.  I'm assuming you have one.

Adjust your valves.  Every adjustment is to be made AFTER you adjust the valves.

Check idle speed when FULLY warmed up.  I set it to just a hair below 1500 indicated on tach. 

Second, you didn't mention how many washers or what mid-mails you have in your carbs.  Your year bike has a 3 circuit carb consisting of pilot, mid-main, and main.  20 is good on the pilot, and 147.5 sounds about right for the main, but what's the mid-main jet?  60 is stock and is anemic for your setup.  I'd start with 65 if you have not replaced already.  I'm also assuming that when you rejetted you replaced the correct main jet.  There have been accounts of people replacing the wrong jet (meaning the mid-main mistaken for the main).

Tach is electronic for your year bike.  Could be a short somewhere.  Others will chime in I'm sure as to what it may be.

That's all I got...Jester

First guess is bad ignition control unit. Since the tach is electronic, it gets the signal from the ICU. For some reason the ICU is sending pulses to the tach. It may also be sending constant pulses to the spark plugs.

In gear and side stand down kills the bike.

Check for spark. The usual - pull the plugs, etc. Let us know what you see with the spark plugs.

ok, so I didn't get it moved today like I wanted because my friends with trucks are quite flakey..anyway I pulled the plugs to see what they looked like:
(sorry for the phone pics)
LEFT SIDE



RIGHT SIDE



So It appears the left side is not only rich but fouling as well. so I pulled the tank to get to the coil,

I have a decent Ohm meter but an not sure what resistance to be looking for? I read that post about Primary and Secondary resistance levels? but how about from the unit itself, perhaps I just need to do a bit more reading.

measured the resistance, it fluxuates a bit but am getting consistant readings around these numbers:

Between (+)(-) on the coil: 14 Ohms
Between the (+) and the plug cap: 31 Kohms

failing?

Spec should be:     
    Primary winding resistance (between + and -): 3.0 Ohm - 6.0 Ohm
    Secondary winding resistance (with plug lead end cap): 18 KOhm - 30 KOhm

Might be a bad coil as 14 ohms is high.  Does the other one read within spec?

Quote from: jestercinti on June 19, 2012, 07:54:41 AM
Spec should be:     
    Primary winding resistance (between + and -): 3.0 Ohm - 6.0 Ohm
    Secondary winding resistance (with plug lead end cap): 18 KOhm - 30 KOhm

Might be a bad coil as 14 ohms is high.  Does the other one read within spec?

I didn't have a chance to check it yet, although you are correct it is rather high.

BUT...

Upon further inspection I believe my CDI BOX ECU UNIT to be the cause. When unplugged the tach. reads 0 when not running, when plugged in the tach. reads 500 RPM, still not running. It is sending a false signal to the plugs aswell...I believe.

And here is the problem it costs $482.00 from bikebandit.com I'm am going to try to find one at a salvage yard with hopes of not have the same problem.

I'm still at a loss how this happened? Faulty part?

While it is apart I figured now is a good time to replace a few things, Valve cover gasket, clean and sync the carbs, pull the front forks re-install with heavier springs and heavier oil adjust the shims on the valves, and adjust the clutch, hopefully I don't need a new cable. Only had a an hour and a half but I made good progress:

Quote from: adidasguy on June 18, 2012, 10:08:23 AM
First guess is bad ignition control unit. Since the tach is electronic, it gets the signal from the ICU. For some reason the ICU is sending pulses to the tach. It may also be sending constant pulses to the spark plugs.

In gear and side stand down kills the bike.

Check for spark. The usual - pull the plugs, etc. Let us know what you see with the spark plugs.

thanks you for the leads and advice I hope this solves the problem.

CDI is what I though, too, a couple days ago. It runs the tach with a series of pulses. Same box that controls the spark.
They're cheap enough to have a couple spares around.

You can source a spare CDI box from here or ebay.  I would check the other coil too and replace the one that measured high.  I'm speculating that a bad coil could eventually damage the CDI, hence your issue. 

I think your mixture is probably ok considering the plugs were mostly brown, but a little fouled probably due to the false sparking issues you are having now.

^^ What bombsquad said.  I'd check the other coil to compare readings just to make sure.

ok, got some more done this afternoon,

Pulled the other ignitor, right on the verge of going over,
Primary: 5.4 Ohms
Secondary: 30.00 KOHMS

So Im going to replace both.

Quote from: adidasguy on June 20, 2012, 04:16:44 PM
CDI is what I though, too, a couple days ago. It runs the tach with a series of pulses. Same box that controls the spark.
They're cheap enough to have a couple spares around.

Thank you for the quick and delightfully packaged CDI units, tested both and they work wonderfully, bike fired right up!! 

Tore into the carbs and looked and cleaned the needls, but here is something questionable, jetting like this:

147.5 Main
130 Mid-Main
20 Idle
I'm 99% sure I read it correctly, should this not be something like 65?

All but one valve was out of spec, once I get my bucket depression tool I can get the correct shims!!