I have replaced the Ignition Coil, plugs and wires, as well as the IAT and Engine Temp Sensors. The bike it still not right. Still back firing, and dying, not starting, and when it does it runs fine until I twist the throttle. Could this just be a weak battery that isnt putting out under loads? I've got it on the charger, but i let it sit over night on 2amp trickle, and it wasnt ready this morning. Maybe its shot? BUT my question is can that be the probelem?
nulloriginal thread
I should explain about my original "load test". I live in Italy, and i took the battery to an Autoricambri (autoparts store) who told me the battery was good. I generaly dont trust these lasy neopolitains, so they probably told me it was good just to get me to leave thier shop...
Hey, I'm posting this excellent post by another Bueller in the hopes this helps you out.
BR
This is a common electrical problem,
Most people, me included, just throw parts at it until it stops happening.
There is another way.
The right way.
Here is a definitive post by Buell technician, Jos51700,(John Self)
To properly test a charging system:
Step 1: CHARGE the battery. Don't do this by revving the bike, do this by charging the battery.
Step 2: Set multimeter to DC volts, and connect directly to battery posts. It should read 12.8-ish to 13.2-ish. If it's lower, see step 1, or replace battery. if your battery is more than two years old, it might not hurt to throw a new one in there, unless you like riding in tow trucks more than riding on motorcycles.
Step 3: Start bike. Battery should NOT drop below (ideally) 9 volts while cranking.
Typically, if it'll crank the bike over at a consistant speed, for a few seconds, it's fine. This is not a true load test, but it's close enough for the homeboy mechanic.
If you own a true load tester, you shouldn't be getting your electrical advice from the internet, anyways.
step 4: at idle, Multimeter on the battery should read 13.5+ volts. Just off idle, to redline, should read 14.4 volts. Less than 14 is serious cause for concern, as is much OVER 14.4. If it's 14.7 or higher, go buy a regulator right now, and avoid running the bike until it's charging at 14.4 or less. Battery explosions suck.
OK, less than 14 volts?
Check: Battery cable tightness, regulator ground, stator connections, etc.
Re-test.
THEN
with bike OFF, unplug stator. Connect multimeter leads to stator side of the connector. DON'T jam your multimeter leads directly into connector, unless you LOVE intermittant electrical issues. Note: now is the time to pray some previous owner didn't JAM his multimeter leads into the connector. If you've ever met one of your wife's ex-boyfriends, you know what I'm talking about.
Once making contact with your multimeter, set it OHM's. It doesn't matter which stator wired you connect to, as you'll try them all. Pick one pair, measure, then swap ONE lead to the other wire. Measure, then swap the lead you DIDN'T move the first time.
3 ohms or less, you're golden. if the meter reads "open" or similar, you're buying a stator. If it reads significantly higher than 3 ohms, you're buying a stator (what's "significant"? 6 ohms or more).
Now check all 3, one at a time, against ground (The engine, frame, chassis, negative battery terminal, etc). It SHOULD read open. If it reads any resistance (Ohms), at all, go buy a stator.
OK. So we know the stator is not fubar'd, yet. Notice we're moving on, and we didn't ohm-check the regulator. That's because there is NO such test. Sorry. You can ohm-check it if you want, but it's not a valid test. I've measured several dozen, some new, some used, some old, some new, some bad, some good. The consistancy just isn't there.
Because the regulator also rectifies, it can fail in many different ways. Undercharging, no charging, failure to rectify, etc. I've seen regulators with the backs melted off, putting out ZERO volts, smoking from the input voltage, and not having a proper ground, and they've ohm'ed out the same as the brand new unit that fixed the problem.
Back to the stator. Bike OFF, switch multimeter to AC voltage. Now, this is the point where the bike can shock you, hurt you, kill you, insult your children, and knock up your wife. You're playing with AC, so no touchie on the wires, okay?
Hook up, start the bike, and measure the AC output between any two wires. Got voltage? Good. Does it increase in a relatively linear fashion with RPM? Good. Honestly, at this point, I don't remember the spec, so maybe someone will chime in with it (Assuming they've read this far). If you have a service manual, it's in there. Now check the other combinations of stator wires, like we did for the ohm-check. If you have smooth, linear AC power starting at the mid-teen range, and ending up at 35 Volts or so, and the output is similar for all three legs, the stator is OK.
It's the behavior more than the actual number at this point, but the number need to be reasonable enough to provide voltage for a 12 volt system.
So if the stator is outputting (and if it doesn't pass the ohm-check, it won't be), and the battery isn't charging 14.4-ish, go buy, and install a regulator, and retest at the battery, looking for 14.4 (DC, you did reset your meter to DC to test the battery, right?) volts. If that doesn't fix it, let me know.
Also don't forget to re-connect the stator to the regulator, before continuing on with other tests, or test rides. Don't ask how I know this.
This may seem overly complicated at first, but print it out, read it, it will make perfect sense.
One additional problem that is not mentioned above, is failure at connector #77, between the voltage regulator and the battery, or the wires that go from 77 to the battery. These often melt or break, so checking continuity from the connector to the battery, and checking the connector is also a good idea. I had a hidden broken wire in this area.
Here is another excellent post by "Rays" that describes checking the voltage regulator.
http://docs.google.com/View?revision=_latest&docid =d4rbxwr_20dq5khf&hl=en
Of course, having a shop manual and parts book doesn't do any harm either.
Here is a chart to show you charge states.
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