Intermittent loss of power

[motoman]

I'll do the wiggling tomorrow. I have 12.6V at the battery. I was touching the negative terminal on the battery. Definitely had decent contact at both points. I'll double check tomorrow though.

Volt meter is what WILL be needed.

[ViperRon]

Maybe a simple explanation of how this works can help you see what you are looking for. Voltage runs the TCI like a computer so with bad voltage it fails under 11 volts most will not work and you get no fire. The pick ups are little coils that pick up the raised portion on the crank and transmit to the TCI which turns on the coil to make a spark at a specific time to get the most power out of engine. The pickups are on a rotatable plate that is controlled by a vacuum solenoid that rotates the plate dependent on vacuum controlled by speed of engine. This is vacuum advance because it creates the firing before top dead center so that the fuel fully ignites at top dead center to get the most power. The TCI actually keeps track of the pulses from the pickups to determine how fast the engine is turning and changes when coils send spark to the plug. The Vacuum advance is low speed change and TCI is higher speed change so they work together. The mechanical vacuum advance moves the assembly and physically bends the wires so a broken wire can be intermittent depending on the bend. Corrosion on wires changes a signal and can cause the TCI to get a bad reading or not work. So any wire not flexible corroded or broke causes a miss or no fire. There are 2 coils allowing the TCI two different positions to fire one position fires 2 and 3 one fires 1 and 4. The later TCI on the 81 models only used the TCI to change timing of the firing of plugs.

[dbeardslee]

No, I didn't do any wiggling. Didn't know I was supposed to.

Checked voltage (had to turn ON the kill switch too), and got 11.2V on gray, orange and red/white. Black/white had no voltage.

I checked the wiring diagram, and if I'm reading it right the black/white runs to the emergency stop switch. Not the kill switch - the emergency stop switch. Looks like this -



Should be right up over the top of the coils in a rubber mount. Might want to pay particular attention to that connector. I'm not sure how you can test the switch itself, but I will consult the manual.

[dbeardslee]

Here's what the manual says -

If any of the tests produce readings which differ radically from those mentioned, the tci is probably defective and may require renewal. Before condemning the unit, however, check that the unit is correctly earthed by measuring the resistance between the black terminal and a convenient sound earth point. A zero resistance reading should be obtained.

[dbeardslee]

I found some info on testing the emergency stop switch -

All models have the tip-over switch, a mercury 'emergency shutoff switch' (but labeled 'emergency stop switch' in the schematic above) that cuts the ignition if the lean angle exceeds 60 degrees. The mercury switch is normally open, and is not likely to short out, but if the sidestand relay is good along with everything else, might as well check that mercury switch by disconnecting the leads and removing it, test for zero ohms when the switch is tilted more than 60 degrees in either direction, and infinite resistance when the UP label is, well, up,

[dbeardslee]

After giving this a bit more thought, when you test the black/white at the tci you're basically shorting the wire out, so it shouldn't matter whether the emergency stop switch is working or not. You're not getting power from the TCI. You said you resoldered the connections inside the TCI, which has me wondering if maybe you've got a cold or cracked solder joint in there. Based on what the manual says maybe it's a good idea to recheck your soldering.

Sorry for ripple-firing these posts. One thought just kind of leads to another...

[CatatonicBug]

I appreciate the insight and ideas.

I have re-soldered the gray and orange pins in the TCI a total of 4 times, the last time removing the solder and replacing it. The only other thing I could do is remove ALL the solder from the connector pins, remove the board from the TCI and replace ALL the solder in the TCI. I need to buy a solder sucker tool before I go there.

I have spliced in several new pieces of wire in the pickup coil circuit (the wires that enter the timing cover). Most recently, this last weekend, replacing a chunk of the orange wire that had exposed notches in the insulation. I suppose I could take the thing apart and replace ALL the wires from the coils to where they exit the timing cover. My main concern is using the right kind of flexible wire (I want to do it right if I'm going that far). Any idea on how to locate/identify the correct flexible wire for the job?

[dbeardslee]

I appreciate the insight and ideas.

I have re-soldered the gray and orange pins in the TCI a total of 4 times, the last time removing the solder and replacing it. The only other thing I could do is remove ALL the solder from the connector pins, remove the board from the TCI and replace ALL the solder in the TCI. I need to buy a solder sucker tool before I go there.

I have spliced in several new pieces of wire in the pickup coil circuit (the wires that enter the timing cover). Most recently, this last weekend, replacing a chunk of the orange wire that had exposed notches in the insulation. I suppose I could take the thing apart and replace ALL the wires from the coils to where they exit the timing cover. My main concern is using the right kind of flexible wire (I want to do it right if I'm going that far). Any idea on how to locate/identify the correct flexible wire for the job?

Flexible multimeter lead wire is generally the wire of choice for the pickup coils. But you have to pay attention to what the diagnostics tell you, and right now there's an unexplained zero volts on the black/white at the TCI. You don't necessarily have to use a solder sucker to desolder connectors. Desoldering braid works real well, and it's real simple to use too. You just place it over the connection you want to desolder, apply your soldering iron to the other side, and it will suck the solder right up into the braid. You can get it at radio shack.

The diagnostics on the pickups so far are in spec, so unless you get fluctuating readings when doing the resistance test when you stretch the wires, redoing the wires may not fix the problem.

I'd try the black wire ground test on the TCI first and see if you get zero resistance. And I'd check the black/white wire on the TCI again, just to verify the zero volt condition.

[dbeardslee]

Let me add something else on soldering. A lot of inexpensive soldering irons get too hot for flux core wire. If you see just a puff of smoke when you apply the heat that's generally telling you that you're burning up all the flux before it can do it's job. I always use an adjustable soldering iron for electronics, and I set the heat so the flux slowly smokes rather than going away in a puff of smoke.

This guy's got a really good tutorial on how to solder - RC Model Reviews

[CatatonicBug]

Oh, no worries on the soldering. My dad's an electromechanical engineer, so I've been soldering since elementary school. The only reason I mentioned a solder sucking tool is the tedium of all the connections. That braid stuff (I already have some) is a pain to use, and not very precise.

So, for tonight, I have 3 things to test:
1. Check the black TCI wire to ground, hoping for no resistance
2. Check the black/white wire on the TCI for voltage (should be 6V)
3. Check the ohms on the 4-pin connector while tugging/wiggling the pickup-coil wires under the timing cover, hoping the readings don't change.

[dbeardslee]

Oh, no worries on the soldering. My dad's an electromechanical engineer, so I've been soldering since elementary school. The only reason I mentioned a solder sucking tool is the tedium of all the connections. That braid stuff (I already have some) is a pain to use, and not very precise.

So, for tonight, I have 3 things to test:
1. Check the black TCI wire to ground, hoping for no resistance
2. Check the black/white wire on the TCI for voltage (should be 6V)
3. Check the ohms on the 4-pin connector while tugging/wiggling the pickup-coil wires under the timing cover, hoping the readings don't change.

The way motoman was describing stretching the tci wires seemed like a real good idea to me. Use both hands and stretch the wires between your fingers. If you've got a broken wire you'll pull it apart that way as the sheath will stretch a bit, and it should show up real definitively on the multimeter, so to me that seems like a real good way to do it.

[dbeardslee]

And one other thing for clarification - the black/white wire is an "ignition on" voltage test. The black to ground test is ignition off resistance test, if I read the manual correctly.

[Ken Talbot]

I've read from the start and I'm still betting on pick-up coil wires being your problem, most likely where all the wires are held under a crimp just before they leave the case. Loosen off the crimp and start up the engine. Now pull and tug and push each wire every possible direction. This is not a "gentle" procedure - pull those wires with some attitude. If the wire is not already broken, you are not going to break it by pulling it with your fingers. If something breaks or you see the insulation stretching and necking down , you've found a problem.

[ViperRon]

Just a little information about soldering de-soldering on the TCI. The board in the TCI has solder runs on both sides of the board and a few are close to each other on the inside where you can not see. It is not easy to get all the solder out of the pin connectors and the solder runs on the board are old and fragile. Solder in large amounts can adhere the run of a connection to a pin it should not connect to easily and the solder can also adhere the board to the pins on the other side not even near the pin location. A hand held solder sucker and some luck and it comes out. A little skill and a solder station that can supply a hard consistent suction is your best bet for success. Now even when you have it out now what??? I have never seen good component identifying set of schematics and its a pain in the ass to component troubleshoot without one I been there and used an octopus tester a cook book and scope comparing pnp and npn connections and I felt lucky to fix one. So know where you are going before you take it out. The other thing is once the bond is broken with a run on the inside it can be near impossible to see if you got it back. If a run on the inside detaches it can drive you nuts getting it back with a good not cold joint. A little too much heat and an inside run will pop off the board and fly up like a heated spring wire. I am in no way doubting you I am just letting you know there is a 60 leg octopus in that box you can only see 30 legs and you have to get them all off at once to take it apart and you have to properly reattach all 60 back for it to work. Yea and you can not see 30.

[dbeardslee]

Randy Rago had some real good stuff on his website about resoldering TCI's, but it appears his site is no more. Or maybe I just couldn't find it. However, I did find his video of this little test to tell whether the problem is between the TCI and your coils or pickups. Might be worth doing this test to see what it tells you before ripping into the TCI - Randy's TCI Test

I also seem to remember that when he talked about resoldering the TCI it was just the big connections where the wires come in, not the circuit board proper. Might be wrong, but that's what I'm thinkin'.