Long story short, my 08 FE550 doesn't seem to be charging the battery when it's been running for a while. It also doesn't seem to be getting a good spark a low revs.
Long story long, I've had this bike for a year or so and it all seemed fine in the beginning. I was running it around town a little, but mostly at supermoto track events (short sessions and high RPM). On particularly hot days, I would notice that it stumbled a little off-idle with a whack of throttle. I modified the accel pump in the carb, thinking it was the notorious lean bog, but that didn't help at all.
I then started riding the bike in the woods on technical single track. Riding it at slow speeds revealed that, when the bike was good and hot, it would stall out if the throttle was opened very quickly from idle. Very frustrating when trying to get over a log! Not a problem at the start of the ride, though.
I discovered that turning the idle screw all the way in (full lean) would help with the bog, but then of course it would run like garbage in the mid-range. This leads me to believe that the spark is weak at low RPMs.
Finally, during my last ride (thankfully near the end of the ride), my battery stopped charging. This really wasn't fun, considering the kick start is jammed up on this bike and the starter is my only hope aside from a bump-start.
As you can probably gather, I think the bog and the charging issue are related. I think I'm getting poor current out of the electrics when they get hot.
I tested the electrics today as per the service manual. I got 12.3V from the battery (engine off) and a consistent 12.5V at the battery with the engine running.
With the caveat that my multimeter is very cheap, testing current through the main fuse I got:
-1.3A unstressed at idle (the manual calls for 1.5+/-0.2, but I think they accidentally omitted the negative sign)
-0.9A stressed idle (manual calls for -1.0+/-0.2)
+0.4A at higher revs (manual calls for 0.8+/-0.2)
Testing stator resistance (same crappy multimeter, engine warm), I got:
red-grn wires: 115ohm (manual: 100+/-20)
blk/red-red/whi: 17ohm (manual: 15+/-3)
ylw-ground: 1.4ohm (manual: 0.65+/-0.15)
ylw-whi: 1.0ohm (manual: 0.16+/-0.03)
Now, the last two numbers are well out of spec, but I suspect that may have more to do with my multimeter and the warm engine than an actual fault, but I'm not really sure about that. I'll test again tomorrow (cold) to see if temperature makes a difference. I also think that since the stumbling problem only occurs after a long, hot ride, I may not see any multimeter faults with the bike only warm or cold.
I guess I'm just not sure where to go from here. Perhaps I'll have to pop off the stator and check for desoldered or baked connections. Anyone have any other ideas? Any help would be much appreciated, as I'm feeling a bit lost and I don't want to just start throwing parts at it without knowing more about what is wrong.
Long story long, I've had this bike for a year or so and it all seemed fine in the beginning. I was running it around town a little, but mostly at supermoto track events (short sessions and high RPM). On particularly hot days, I would notice that it stumbled a little off-idle with a whack of throttle. I modified the accel pump in the carb, thinking it was the notorious lean bog, but that didn't help at all.
I then started riding the bike in the woods on technical single track. Riding it at slow speeds revealed that, when the bike was good and hot, it would stall out if the throttle was opened very quickly from idle. Very frustrating when trying to get over a log! Not a problem at the start of the ride, though.
I discovered that turning the idle screw all the way in (full lean) would help with the bog, but then of course it would run like garbage in the mid-range. This leads me to believe that the spark is weak at low RPMs.
Finally, during my last ride (thankfully near the end of the ride), my battery stopped charging. This really wasn't fun, considering the kick start is jammed up on this bike and the starter is my only hope aside from a bump-start.
As you can probably gather, I think the bog and the charging issue are related. I think I'm getting poor current out of the electrics when they get hot.
I tested the electrics today as per the service manual. I got 12.3V from the battery (engine off) and a consistent 12.5V at the battery with the engine running.
With the caveat that my multimeter is very cheap, testing current through the main fuse I got:
-1.3A unstressed at idle (the manual calls for 1.5+/-0.2, but I think they accidentally omitted the negative sign)
-0.9A stressed idle (manual calls for -1.0+/-0.2)
+0.4A at higher revs (manual calls for 0.8+/-0.2)
Testing stator resistance (same crappy multimeter, engine warm), I got:
red-grn wires: 115ohm (manual: 100+/-20)
blk/red-red/whi: 17ohm (manual: 15+/-3)
ylw-ground: 1.4ohm (manual: 0.65+/-0.15)
ylw-whi: 1.0ohm (manual: 0.16+/-0.03)
Now, the last two numbers are well out of spec, but I suspect that may have more to do with my multimeter and the warm engine than an actual fault, but I'm not really sure about that. I'll test again tomorrow (cold) to see if temperature makes a difference. I also think that since the stumbling problem only occurs after a long, hot ride, I may not see any multimeter faults with the bike only warm or cold.
I guess I'm just not sure where to go from here. Perhaps I'll have to pop off the stator and check for desoldered or baked connections. Anyone have any other ideas? Any help would be much appreciated, as I'm feeling a bit lost and I don't want to just start throwing parts at it without knowing more about what is wrong.
Last edited:
