3aj rebuild wiring issue

[Dino Dakar]

Hello all,

Picked up a very used 88 Tenere last year and continued to give it a hard time and absolutely loved it! Well as it goes I decided to do a full rebuild, powder coating, plating, and splitting the motor etc. Its been a journey discovering how shagged this bike was and the length I have gone to get it right.
I am having an issue with the ignition where I have no spark at the plug. I would be very grateful if someone could give me a hand trying to resolve this issue.

The following is where I’m at

* the bike was running fine when I stripped it.
* all the wiring loom has been cleaned and checked.
* battery fully charged.
* new oem stop start switch installed. Note existing was working fine but was damaged. Changed it back and have the same issue.
* new after market ignition switch.
* brand new plug test for continuity and ohms.
* the clutch kill switch was bypassed when I got the bike and has been left as it is. It’s working normally if I release the terminal block I have nothing and won’t turn over.
* Australian delivered bike with no side stand kill switch.
* neutral switch working as per normal.
* existing ignition coil. Tested primary coil within service manual specs. Tested secondary coil within service manual specs.
* starter circuit cut-off relay is “clicking” when the ignition is switched on.
* the rectifier/regulator from my understanding shouldn’t effect the starter circuit just the charging. Found a YouTube clip in Spanish about testing the rect/reg. Followed it and from the clip shows that mine is faulty. Purchased another new one and will have it very soon to test.
* the stator pick up coil resistance is within the service manual specs.
* the stator coil resistance is within the service manual specs.
* checked the cranking voltage off the stator/ red wire and brown wire. The red wire was 4.7v avg on cranking? The brown wire was 3.7v avg on cranking?
* also tried to crank the bike with the black/white wire disconnected off the cdi with no results.
* also sourced a second cdi from a guy here in Sydney to test. From his knowledge the cdi was working when removed. Tested it and it was doing the same thing.
* if I crank the bike longer it occasionally shows a very weak spark.
* checked all my earth connections.
* wired earth lead direct to the plug when testing.

From the above there is no power feeding the coil from the plug. I have done a lot of googling to get on top of this but have been hit by a curved ball and at my wits end. Some insight would be greatly appreciated.

Cheers
Dino

[scottieh]

Try snugging the spark plug boot farther down on the coil’s wire. It’s possible for that boot to slide around and separate from the wire, causing weak to no spark. Also check for corrosion on the plug wire while you’re fiddling about in there. I’ve seen some nasty looking connections between the plug and wire due to too much of a gap and the spark arc’ing.

[Dino Dakar]

Hi Scottieh,

Yes I checked the connection on the plug lead and did some further testing with no luck.
Would someone know what the voltage should be on the stator when cranking the bike over. It would help me eliminate if the stator has problems. Thanks again.

[dzl]

I would be expecting at least 40-50V AC output from source coil open circuit with plug disconnected. I think thats what my 34L had What resistance do you have on source coils? Should be around 120 ohm.

[scottieh]

Let us know your results based on this 3AJ service manual. I’ll try and check my stator output tomorrow and post my results.

[Dino Dakar]

All the resistance tested on the pickup coil are within specs. Not sure where the charging coil white/yellow- white/yellow wires are? Also the source coil resistance number on that page are different to the ones at the back of the book. The resistance there was 139 ohms are not in spec but are in the back of the manual.
I’m away and will be back home on Friday. When I get back I should have a new rectifier/reg and a new nos coil as well to test.

[scottieh]

Hi Scottieh,

Yes I checked the connection on the plug lead and did some further testing with no luck.
Would someone know what the voltage should be on the stator when cranking the bike over. It would help me eliminate if the stator has problems. Thanks again.

The output AC voltage of the stator’s three white charging wires is 19.5 volts. That was tested while the reg/rect connection was disconnected and the bike was at idle

[dzl]

Thats for the charging circuit and irrelevant to this apparent ignition issue.....need to ensure that the source coil is producing an output. That is what supplies the power for the ignition.

[motorang]

Hi

Did you try pushstarting downhill or towing? The voltage drop seems pretty spectacular to me when electric starting. Or try hooking up a car battery for a test start. Maybe the relais/cdi is underpowered just when the starter is turning over.

I then would try wiring the cdi and ignition coil directly to the alternator loom for a test.
As the bike was running before and all components seem to work fine it is most likely a cabling issue.

Andy

[Dino Dakar]

Found out the issue. The pickup coil was mounted the opposite way!!!!!!
Thanks for all who posted with a reply. Greatly appreciated.
The bike has started and runs well, with the only issue of checking the oil pressure and potential oil leaks.
I will start another post once everything is bedded in with some pictures of the completed bike.
Cheers
Dino