Cold start problem

[BA80]

An update on this problem.

Doc and I spent 3 - 4 hours on this today. For some reason the TCI isn't getting the signal to fire the coils. It will now and then spark when cranking but not steady. If I mess with the kill switch it will spark more frequently but still not steady.

Here's what we've tried....

1) Checked power to coils....11.5V

2) Ohmed out pickup coils....650 ohms both

3) checked air gap on pickup coils .... .7mm

4) checked continuity of wires from TCI to pickup coil plug......good

5) disassembled kill switch and checked it.....good

6) disconnected tip over switch.......no difference

7) swapped TCI's....no difference

Will occaisionaly spark when start button is released.

All done with charger connected w/ 13.5 volts at the battery.

I need some ideas y'all.

[motoman]

Will occaisionaly spark when start button is released.

Disconnect/bypass ballast resistor.

[BA80]

I forgot put that on the list. We actually swapped that out with another I had here.

It actually sparked several seconds after the start button was released once.

[TopCatGr58]

Hey Greg,

Did you check the voltage to the TCI? You swapped TCI's, but it if/they are not getting enough volts, they won't work to trigger the coil. The rare spark seems more like it's just from the dropping of power to the coils after you stop trying to crank. Check the voltage on both sides of the fuse for the Ignition circuit. I would bet that you have some corrosion on the wires/plugs to the TCI so it's not getting the 10.5+ volts it needs!

T.C.

[BA80]

Been through the fuses, which wire do I check at the TCI? As I said before I'm getting 11.5 volts at the coils and that goes through the TCI.

[crazy steve]

Have you checked the 'quality' of the ground wire to the TCI? If that has a poor connection, that could do it....

[CaptonZap]

Been through the fuses, which wire do I check at the TCI? As I said before I'm getting 11.5 volts at the coils and that goes through the TCI.

The red/w white at the 8 conductor plug on the TCI supplies the current used by the electronics inside the TCI. They control the output transistors, two, one for each coil, which act as switches, or points, for us old guys, that interrupt the current flow through the coils, causing the field collapse and spark that we all know and love.
A quick test of the coils is to take the orange and gray wires out of their connectors, hook a jumper to each of those wires from the coils, turn on the ignition, and take the other end of the jumper and wipe it quickly across a good ground, like you were striking a match. The coil should spark. This assumes that the spark plugs are out of the head, laying on the metal engine, and hooked into the spark plug boots. If they spark, there is something towards the TCI that is not right.
And I'd guess that Steve's ground check is a good possibility.



And don't try to fade off into the darkness after you figure it out, like a lot of other people do, and not let us know what it was. We know where you hang out, and We will come for answers
Besides, James England is keeping score, so we don't want to upset his scoring system.


CZ

[RockinD]

The red/w white at the 8 conductor plug on the TCI supplies the current used by the electronics inside the TCI. They control the output transistors, two, one for each coil, which act as switches, or points, for us old guys, that interrupt the current flow through the coils, causing the field collapse and spark that we all know and love.

So my limited understanding of all this is that the TCI box is the points for the coil and it provides the ground side of the coil circuit.
And in general the circuit has 12 volt on the circuit when it's "GROUNDED" ( in otherwords -points closed) and when the circuit is "OPEN" (i.e. -points open) then you'd have no current?

We did hook up a test light (but used a digi meter) and did find the ground side of the coil, hooked that test lite to a good ground and took the pointy tip of the test lite to probe the terminal near the TCI box and saw the light strobe as the engine was cranked.
Am I right Greg?
What are we missing?

[CaptonZap]

So my limited understanding of all this is that the TCI box is the points for the coil and it provides the ground side of the coil circuit.
And in general the circuit has 12 volt on the circuit when it's "GROUNDED" ( in otherwords -points closed) and when the circuit is "OPEN" (i.e. -points open) then you'd have no current?

We did hook up a test light (but used a digi meter) and did find the ground side of the coil, hooked that test lite to a good ground and took the pointy tip of the test lite to probe the terminal near the TCI box and saw the light strobe as the engine was cranked.
Am I right Greg?
What are we missing?

Your understanding is right on, the only variance is that after the start solenoid de-energizes, the coils are only fed 9 volts, +/-, through the resister. The TCI still gets 12+ volts, or should, through the white/red wire.

Was the coil still hooked up when you took the pointy end of the test light to the wires at the TCI? The two wires to the coils are orange and gray, orange to the left side, #1&4, gray to the right, #2&3. Are your wires reversed?
It sounds like the TCI is working, so it has to be the coils or wiring. Try the 'strike a spark' test with the coils, and see if they are good.

CZ

[BA80]

Ok, I'm here to say that even if you try something once try try again.

This was eating at me today so I went out and messed with it again. I made sure the grounds were good...........no joy. Being in an extremely frustrated state I figured I would start all over again since we had tried everything and nothing had made a difference.

I got another TCI and plugged it in and HOLY CRAP! I GOT SPARK!!!!

I tried the TCI we had tried before and still had spark WTF? plugged in the TCI on the bike and............nothing. It was the TCI all along.

The only thing I can figure is that when we tried another TCI before we weren't getting a good connection at the plug and messing with it cured that issue.

Just goes to show you that if it doesn't make sense you probably did something wrong.

[crazy steve]

Greg, I'd be willing to bet that wherever that bad connection was, that probably took out the first TCI.

One thing to remember about electrical circuits; poor connections can cause different things depending on the connected load. Resistive loads will 'see' an increase in circuit resistance from a poor connection as simply a voltage drop, with little or no current increase, so damage if any is usually limited to the poor connection. Inductive loads on the other hand are trying to perform 'work', whether it's a motor or ignition coil, and will try to do it's designed function at all times (like firing spark plugs or trying to spin a motor to start it), so when voltage goes down, current will go up as it tries to keep doing the same 'work'. Too much current and the factory smoke escapes....

[BA80]

Yeah, a bad connection will overheat a circuit and destroy circuit boards and their components..

I'm fairly certain that the weak connection was at the large plug on the TCI. As I stated earlier Doc replaced a lot of the plugs in the harness due to a fire. I found 3 connectors in that plug yesterday that were not fully seated into the plug. 2 0f them being the power and ground wires.

A bad connection that close to the circuit board no doubt melted some solder at the very least.

An enomoly that the temp made a difference.

[ViperRon]

One other thing that can cause the conditions you describe is leakage from carbs back into cylinders. Your bike sits and the carbs leak for a bit then it stops before the puddling and it runs into 2 cylinders. With the bike cold the chance of cold fouling the plug is much greater and if you have a weak spark and or low cold compression it is worse. So you end up starting cold on two cylinders an then as it warms the plugs start firing and it runs fine till it sits for a while. This type of thing is very intermittant as you know float leak problems can be very intermittant. Just one more thing to look at. I would bet you have electrical issues but might not be all of it as electrical issues do not generally just go away after warm up.

[BA80]

Ummmmm...........it was the TCI Ron.

[BA80]

I spoke too soon. I thought we had it fixed but........NOT!

We rode 80 or so miles last weekend no problems, I tried to start it the next morning an no spark again.

I can't find ANYTHING wrong. Every now and then I get a spark.

Why the hell would it be fine when it's warmed up but just not spark again after sitting all night?