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Steve
Steve, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 6828
Experience:  30+ yrs. experience, MMI, HD technician, HD early, engine rebuild/performance, bike builder, kit bike program manager, CCI 2001-2004
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I have an 03 harley sportster 1200c. 7000 miles. I am having

Customer Question

I have an 03 harley sportster 1200c. 7000 miles. I am having a very hard time getting my bike started. It backfires badly when cranking. Right when i stop let go of the starter button it usually will backfire very loudly. Getting the bike started pretty much drains the battery. It seems to be running rich because of black spark plugs. I've replaced all the intake gaskets and cleaned the carb very well. I've also replaced the sparkplugs. When It does finally crank up it seems to run fine and will restart quickly as long as the engine is still hot. Once it cools a bit it wont start back up. I cant figure it out. I feel like I'm not getting spark. If I use starter fluid it doesn't respond at all to it. Could this be a ignition module failure?
Submitted: 1 year ago.
Category: Motorcycle
Expert:  Steve replied 1 year ago.

it is an ignition problem, but I suspect the ignition is OK and the problem is a battery issue.

to find out, measure the battery voltage under the following conditions:

- ignition OFF.

- ignition ON.

- with the start button depressed.

- and after starting, with the engine at about 2,000 rpm (fast idle).

let me know what you find.

Steve

Customer: replied 1 year ago.
Ok, so, yesterday I got a brand new battery because the one on the bike was 5 years old and wanted to rule out a faulty battery.Voltage
Ignition off- 12.78
Ignition on (not running) - 12.78
Starter button depressed - 10.5ish
Slow idle - 4.08 - 5.71
fast idle - at first dropped to 2.5 then slowly climbed to 4.72 - 5.66
Expert:  Steve replied 1 year ago.

your charging system has failed.

you may have an issue with the stator or the regulator, or both.

I can help you figure that out.

- with the ignition OFF, disconnect the regulator from the stator.

- measure the resistance of each STATOR side connector pin to ground (use the engine case as ground, use the highest OHM scale on the meter)

let me know what you find.

in the mean time, I have diagnosed your problem as a charging system failure resulting in a low charge on the battery, resulting the starting issues you experienced.

I would appreciate if you rate my answer with a POSITIVE RATING.

this will not prevent us from continuing the troubleshooting to find and correct all issues with your charging system.

Steve

Customer: replied 1 year ago.
The engine turns over perfectly fine so how does the charging system affect the engine not getting spark when there is plenty of batter power?
I got infinite ohms on each side so the stator isn't shorted.
I got 0.0 ohms of resistance with black and red meter wires in each side of the plug.
I also checked the alternating current when running at 2000 rpm and got 52v
Expert:  Steve replied 1 year ago.

you are getting ahead of yourself. one problem at a time!

your charging voltage is 5v. it should be 14.2 v.

your charging system has failed.

I am trying to help you resolve that issue.

if your stator is good, replace the regulator. it is the only other part.

then repeat the battery voltage measurement at fast idle. (only at fast idle....measuring the charging voltage at slow idle tells you nothing) it should be around 14.2 vdc. let me know if it is not.

as for not getting spark...your engine started when you replaced the battery, correct?

problem solved.

a failed voltage regulator allowed the battery to deteriorate to an unusable condition.

please leave a POSITIVE RATING.

thank you,

Steve

Customer: replied 1 year ago.
you spotted a problem with the charging system. But the new battery didn't change anything. The major issue isn't that the battery is dying. It only died because trying getting the bike to turn over takes so long. The issue is that it's extremely hard to get started when cold. My bike used to crank perfectly every time. Now it doesn't. It will however crank right up if the engine is still warm.
Expert:  Steve replied 1 year ago.

you posted NONE of that in your original question.

so, now that we have resolved the issue in your ORIGINAL question, you would like to discuss A HARD STARTING ISSUE?

IS THAT CORRECT?

Customer: replied 1 year ago.
You have resolved nothing! I never asked you about why my battery was dying! I asked you to help me figure out why my engine is having so much trouble starting when cold!
Expert:  Steve replied 1 year ago.

the answer to your original question....the one you posted above....is a bad battery.

the reason for the bad battery was due to a 5 year old battery and a failed charging system.

Steve

Customer: replied 1 year ago.
If that was the answer then why is my bike still doing the same thing with a brand new battery! Still doesn't start!
Expert:  Steve replied 1 year ago.

how did you measure stator out and battery voltage at fast idle if it didn't start?

Customer: replied 1 year ago.
It does start eventually but it about drains my battery trying to get the bike started. It no longer fires right up like it used to. It backfires and coughs really bad while trying to get it started like I originally said. Takes a good 10 mins to get it started. And sometimes it doesn't start because in The battery is drained from all the power going to the starter. The battery isn't draining because there's a charging problem. The charging system can't work and less the bike is running.
Expert:  Steve replied 1 year ago.

fabricate a jumper (at least 16 ga) that connects to the spade terminal on your starter to the terminal with the POS battery cable.

- remove the relay wire from the spade terminal on the starter and connect the jumper.

- touch the bare wire of the other end of the jumper to the terminal with the POS battery cable.

tell me how well the starter cranks the engine. same or better?

Steve

Expert:  Steve replied 1 year ago.

let me know if you need more help.

if not, please leave a POSITIVE RATING.

thank you,

Steve