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Discussion Starter · #1 ·
Hello,

Hope you guys can help me out with a strange problem I have on my scrambler ‘07. I bought the bike for a project and don’t know the history, but everything looks almost new.

Since I have the bike it never ran. It started without a spark (left and right). Therefore I bought a new CDI/igniter unit. After installing the new CDI, it sparked on the left. I changed spark, spark cable and coil from left to right and still no spark on the right.

I changed the pickup coil and still no spark on the right, only left.

I checked the cable from CDI to spark coil and that was also a good connection.

Now I’m really running out of options... I hope someone can help me out!
 

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So the bike only has one coil, and you changed it with a known good or new one. Next would be the Crank position sensor. First, check the gap at the crank / sensor pick-up point. 0.08mm is the specification. Also, do an ohms check on it, cold and hot [ heat gun ].
I know these notes are not for your situation but should offer some guidance and maybe help.
Here are my notes:

Crank Position Sensor:

When the bike runs fine only before the engine heats up, you can usually blame the crank position sensor. These are also known as the pickup coil which signals the bike's computer (ECU) to fire the spark plugs. The main ignition HT coil can also produce the same problem, but this is very rare in comparison to the position sensor, and is also more expensive to replace, so it's worth starting the fault tracing with the cheaper option.

The very thin wire that is in the pickup coil windings can break due to expansion from heat and cause a loss or partial loss of spark. When the engine cools again the coil contracts and makes full contact again. The way to test the pickup coil is to take 2 resistance readings, one when cold and the other when hot. You can do that by removing the coil, taking a cold reading, then submerging the coil in boiling water for a few minutes before taking the second reading. The cold reading should be around 200 ohms +/- 20%, and if the hot reading differs greatly from the cold one by more than a few ohms, this indicates a faulty coil.
 

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So the bike only has one coil, and you changed it with a known good or new one. Next would be the Crank position sensor. First, check the gap at the crank / sensor pick-up point. 0.08mm is the specification.

Should be 0.8 mm
 
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Why would the crank position sensor affect only one side?
 

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Why would the crank position sensor affect only one side?
I don't know that it would, but it has pretty much covered everything else that is in the producing a spark or spark signal items.
Thank you for the correct gap setting - my mistake.
 

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There is another test you can perform to check the low voltage wiring. When the ignition is turned on it supplies voltage to the coils which then goes to the
igniter unit which turns them "off and on". Turn on the ignition switch (with engine stop switch on as well) and check for 12 volts at the coils. You said you already checked
continuity of the wires from the coils to the ignitor: this test also can be performed by checking the voltage at the connector that plugs into the ignitor. That would
check all the wiring. With the ignitor cable disconnected from the ignitor, check voltage to ground with the ignition on at pins 8 and 14. (Pin one is located at the bottom right corner
of the connector when viewed from the back. Pins are numbered right to left.)
 

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I did not put a question mark, but I was asking the poster that question to see if he changed one or two coils.
So we still do not know that answer?
 

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Discussion Starter · #10 ·
I don't know that it would, but it has pretty much covered everything else that is in the producing a spark or spark signal items.
Thank you for the correct gap setting - my mistake.
I can not imagine why a pickup coil would only produce a spark on one side. Just to be sure I checked the gap on each of the three pins on the rotor. The gap was everywhere 0.8.


I did not put a question mark, but I was asking the poster that question to see if he changed one or two coils.
So we still do not know that answer?
I changed left coil, to right en right to left. I still only had a spark on the left side. I did not only change the coil, but everything after (cable, sparkcap, sparkplug) as wel, just to be sure. Problem remained the same....
 

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Discussion Starter · #11 · (Edited)
There is another test you can perform to check the low voltage wiring. When the ignition is turned on it supplies voltage to the coils which then goes to the
igniter unit which turns them "off and on". Turn on the ignition switch (with engine stop switch on as well) and check for 12 volts at the coils. You said you already checked
continuity of the wires from the coils to the ignitor: this test also can be performed by checking the voltage at the connector that plugs into the ignitor. That would
check all the wiring. With the ignitor cable disconnected from the ignitor, check voltage to ground with the ignition on at pins 8 and 14. (Pin one is located at the bottom right corner
of the connector when viewed from the back. Pins are numbered right to left.)
What is it exactly what I'm checking with this? Because i'm not really a electrical specialist, but learning every day :)

Edit: And to be sure. With coil you mean the spark coils of pickup coil?

Edit 2: Is it correct that you mean the cable from the ignitor to the right coil might be grounded? This is something I did not check yet, but will do!
 

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Well - you have done a good amount of troubleshooting to no avail. if it were mine at this point - I would probably recheck all the leads, caps, plugs, and coils, just to reverify that I go it right. I do that when I am trouble shooting so it does not come back to bite me that I missed something way back in my troubleshooting. If that all rechecked out good, I would then be going to the wiring from the ignition control unit through the looms.
Tough one for sure. has to be something - you'll find it. Remember, easy things first.
 

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What is it exactly what I'm checking with this? Because i'm not really a electrical specialist, but learning every day :)

Edit: And to be sure. With coil you mean the spark coils of pickup coil?

Edit 2: Is it correct that you mean the cable from the ignitor to the right coil might be grounded? This is something I did not check yet, but will do!

This test is right out of the Triumph shop manual. I'm talking about the ignition coils (what you call the spark coils). When you turn on the ignition, the coils
receive 12V from the ignition switch. The voltage passes through the coils and goes to the ignitor. This test ensures that voltage is available to the coils, and
that the wiring to the ignitor is correct.
 
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