No sparks = no go

[Rasputin]

The gap between the reluctor plate and the pick-up coils is supposed to be .7mm.

[LoHo]

Gentlemen, I appreciate your efforts and I want you all to know that these discussions always increase my knowledge of what's going on with this bike, so I thank you all.

I have a new starter on the way, as I think that may be a problem regardless of anything the current issues. I guess the next step, if that doesn't solve anything, is trying out a known good TCI, so thanks, Ray, I may take you up on that offer.

This I do know: If I haven't solved this by Rally Time, I'm dragging her down with me and you guys will have her running before I feed anyone. Just saying...

[cywelchjr]

im not arguing with your theory,
but its not part of the 'loop'
your refering to, the best way i could put it
would be to disconnect the b/r without joining the wires,(open circuit)
you would still get 12 volts to the tci but you wouldnt be getting
12 volts to the coils, according to your theory, the loop would be
broken and the tci wouldnt be getting any voltage.

The TCI provides momentary shorts on the neg side of the coils, which causes the current flow that makes the coil work. Everything that goes through the coil, and the ballast resistor goes through the TCI as part of the circuit.

[cywelchjr]

So, just to confirm (because I want to put 3 ohm coils in).. On the standard setup, the coils are 1.5 ohm. This lower resistance (compared to 3 ohm) allows the coils to draw 8 amps when the starter is pressed and this gives a better spark while the button is pressed (or 'depressed', as they say in the manuals... sounds sad). Then, when the starter button is released, the ballast resistor kicks in and lowers the amps drawn down to 4 amps. The TCI can handle a short burst of 8 amps going through it whilst the bike is being started but wouldn't be very happy if it had 8amps going through it all the time. So... BAD idea to bypass the ballast resistor when standard coils are fitted as the system will be handling double the amps is supposed to when the engine is running. But, when 3 ohm coils are fitted, they draw only 4 amps (because of their higher resistance) and the ballast resistor can safely be bypassed by joining the terminals together on the wiring loom.

Correct???

Only partially correct. Since the resistor is only bypassed during cranking, the voltage applied is reduced, probably to something close to what the resistor provides. So, you don't get 8 amps during cranking, but you probably do get something more than 4, and yes the TCI can handle it for a short while, but over normal operation times it will fail as the weak point. The power transistors that switch the current on and off to make the coils work can only handle so much current over a long time without overheating and losing the magic smoke.

[DiverRay]

This I do know: If I haven't solved this by Rally Time, I'm dragging her down with me and you guys will have her running before I feed anyone. Just saying...

That's OK LoHo, as we can bring along some beef jerky and beer to get by on until the bike is running!

[petejw]

After a few pms back and forth with crazysteve
explaining a cpl of things i was wrong with regards to bypassing
the ballast resistor affecting the tci, so apologies to steve and thanx for ur patience.

[DAVINCI]

The TCI provides momentary shorts on the neg side of the coils, which causes the current flow that makes the coil work. Everything that goes through the coil, and the ballast resistor goes through the TCI as part of the circuit.

Remember points? They fire coils when they OPEN. Our TCI does the same, that's why when he turns off the key he gets a spark.

[skids]

Magic black box talk & ballast resistor

I am pretty sure that LoHo just needs some advice to get her going...
Cleaning the connections and a temporary swap with a known good box seems like a good way to check things out.

[cywelchjr]

Remember points? They fire coils when they OPEN. Our TCI does the same, that's why when he turns off the key he gets a spark.

If the ignition system (TCI) is working properly it shoudn't. It's supposed to shut off the coils if the engine is not running, which means it should NOT be pulling it's side of the circuit low until it starts see pulses from the input coils down below. Now, it might have pulled them low if it had actually been trying to spark while cranking, but it should shut that off within a few second of the engine stopping it rotation.

[DAVINCI]

if the ignition system (tci) is working properly it shoudn't.

there you go

[3Phase]

You can also get a single spark after cranking the starter without an ignition fuse or even if the kill switch circuit is bad. I haven't tried it with the tipover switch activated and I just got back from Arizona a little earlier this evening so I'm not motivated enough to go outside and pull the gas tank off to test it tonight.

Anyway, just like an old Chevy or Ford starter solenoid circuit: when the the starter solenoid is activated or jumped it turns on the starter motor and feeds bypass voltage and current to the ignition coil(s). On the XS11 the bypass voltage and current go up and into the TCI via a Red/Yellow wire and then back out on a White/Red wire to a junction point just before the coils but after the ballast resistor. It looks like there is a simple junction inside the TCI between the Red/Yellow bypass wire and the White/Red coil primary wire but I have not torn up my working TCI to make sure it is actually connected the way it shows in the schematics.

The ballast resistor is not a diode so, of course, the full bypass voltage and current that feeds the ignition coils to start the engine also backfeeds a reduced voltage and current through the ballast resistor to the primary ignition circuit and the TCI.

The TCI will receive enough voltage and current from the ballast resistor to energize the ignition coil output transistors and if the TCI is any good it can start and run the engine. When you turn off the the ignition switch, release the start button or remove the jumper then the bypass voltage and current disappears and the TCI turns off so there may be a single spark from one or both coils.


To do a very basic and quick test: Use a jumper on the starter solenoid from the battery (+) terminal to the starter motor terminal. If the ignition system is working and you remembered to put gas in the tank then engine should start and run until you remove the jumper.

Normally the TCI will shut off the output transistors if it senses that the engine is not turning (no pulses received from the pickup coils) so you don't run down the battery or fry the ignition system if you leave the ignition switch on with the engine not running but it can be 'fooled' and produce a single spark after cranking the engine and removing power from the TCI.

Pretty neat, eh? Are you confused yet? And now it's time for me to go jogging, then pick lint off the dog!

[cywelchjr]

You know, the only thing I have not seen confirmation of being done is unplugging the tipover switch. If that goes bad it will show pretty much the symptoms that are happening, and it's simply a matter of unplugging it to test it, as it just provides a ground to shut off the TCI when activated, and the ring in there has been known to get stuck to the side and the bike won't run or give any spark.

[LoHo]

The tip-over has been removed and even replaced to no avail.

[cywelchjr]

Ok, that answers that question. I'd say it's looking really suspicious for the TCI at this point. I'm seeing a lot of fingers pointing in it's direction.

[LoHo]

The plot thickens...

Having exhausted my meager technical skills, I decided to throw PayPal credit at the problem and replace parts until she works. I bought a starter from Andreas; she cranks the same as before. I foolishly bought a TCI from eBay before reading Andreas' reply, got that today, plugged it in and...same results. I was so certain that a different TCI would work that when it did not, I just shut the garage down, went inside, and sat on my butt watching tennis.

Keep an eye on eBay for some great deals as I part this b---h out.

I refuse to believe that both coils would fail at the same time, but...how much room left in the PayPal?