Last Friday, I was going to meet some guys and Fallbrook to cruise around De Luz. Fun place if you like twisty roads with a lots of ups and downs.. Anyway my 2000 FXDX wouldn't start so I took another bike. The Bike had run fine 12 days ago when I put over 100 miles on it on other twisty roads..

Saturday I proceeded to trouble shoot the issue.. Pulled the plugs and they looked like crap.. Most likely because the bike could start. It's an all bore 107 so it works the starter but usually fires right off. New plugs made no difference. Since the plugs were out, compression read, 190 front and 185 rear.

I suspected weak spark. So the first thing I did was check the crank sensor. Bike has 70000 miles on it and has had a hard life as a 95/116/107. Blew the motor up few years ago so suspected the cranks sensor was weak. Turns out is wasn't. Ohmed out at 1035 ohmes. While cranking it put out also 5 volts..

Add:
I also checked that the ignition module didn't die by read the current EEProm map / settings out.. It was still correct.

 

Checked the coil primary by first connecting the leads together then across the primary windings. Subtracted the lead resistance from the primary reading and both were 0.6 ohms..

 

Checked the secondary windings and found one open. The other was in spec so I replaced the coil.. Bike lit right off with the new coil.

 

Why didn`t you just replace the starter, then the battery?

Excellent post Max.

 

Well Dan, I probably should have replaced the battery at the same time..

Bike got harder to start so it's been sitting some.. Cranking speed seemed OK. Then bike wouldn't start. When cranking it would backfire through the exhaust. Sounded like a pistol round, nice flame about 8 inches long out the exhaust. The starter seems to be cranking OK. Bike seemed to be behaving similar so I thought it was the ignition module. I tried replacing the module and had the same issue. I figured to check the cranking voltage and found that it was dropping to 6.45 volts. I have a reasonably good LI battery out of another bike and got less drop. Motor lit right off, after another backfire though the exhaust.

The battery has in interesting failure.. Typically the impedance goes up and the battery self discharges but on this one the voltage reads a little low and my battery tester says it's got 320 CCA. Though the battery voltage is low (12.0V) the charger took longer than an hour (6 amp) and it still didn't fully charge.

This volt meter has a min / max which makes it good for measuring voltage drop when starting. Should have done this test when replacing the coil.


Original battery while cranking

LI Battery

 

Well I placed the battery that I thought was bad on the charger. It did take a while but fully charged.. My battery tester said that the CCA was was about 340. I let the battery set for a few days and it didn''t loose voltage. Something else must be wrong.

Checked battery voltage with motor running and it read 13 volts when brining the RPMs up (LI battery). Crap it ain't charging. I popped apart the alternator connector and checked resistance. Coil was 0.1 ohm. To ground it was 0.1 ohm. Pulled the primary and the stator is fried.. I decided to replace inner primary seals while at it.. The inner primary bearing race had walked but I was able to get bearing knives behind it and pull it out far enough to used a Jim's puller.

 

Good trouble shooting Max.

Preventative maintenance is much better than being broke down on a ride.

.

 

I gotta ask, "What's a bearing knife"?

I've never heard fo using a bearing knife to move a walked bearing.


I googled it and all I got were folding knives with bearings...

 

Google Bearing Knife Puller gets some of the right pics. It's really an external bearing puller for pulling bearings off of shafts that have a flat surface behind.. Used these a lot when rebuilding MC cranks that had ball bearing mains. The inside is kind of sharp to get under the bearing and start pulling it off.

 

Thanks....

Adding "puller" after Bearing knife got the right stuff...

I learned something new today...

As always, I appreciate the education...