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[rayivers]

After searching this forum quite a bit and finding some really good stuff, I figured I would ask for input about my '14 FX 5.7, which is now pretty much an MX.  This bike was bought used a few weeks ago with 219 mi. on it, already converted for dirt use.

Using one battery, this bike feels noticeably less powerful and 'snappy' than my '14 FX 2.8 (bought new in Feb '14, no problems, I love it). Using two batteries - which I never do, except for troubleshooting this bike - the 5.7 still feels sluggish under 40 mph, but much faster than the 2.8 above that.  Unlike the 2.8, switching modes seems to have little effect.

This bike came with the chain kit installed (5.42:1 ratio, stock belt was 5.28:1) and big Dunlop knobbies front and rear.  The rear is 27.5" diameter, 2.5" bigger than the OEM tire (10% gear reduction factor, effective final chain-drive ratio @ 4.93).  It's also had the motor-recall 'torture test' performed, which was described to me as full-throttle running on a stand for 20 minutes (no mention of temperature).

More 5.7 symptoms:

1) The bike exhibited intermittent BMS and contactor errors, and a flashing display at one point.
2) The dash temp display reads 106F for @ 86F ambient (2.8 is within 1 degree)
3) Dash hi-temp indicator comes on solid at an indicated 240+ degrees (see above) after ten minutes of medium-to-fast riding. 'Thermal strategy' activates.  Actual motor fin temp reading 143F after stopping.
4) Motor has (to my ears) a high-pitched whine above 40mph the 2.8 doesn't have, quite different from the "zizzzzz" zipper-type chain noise.  This whine is worse with two batteries.

Any and all input welcome.  I was an electronics tech in the maritime industry for 38 years and have a very small amount of motor/controller training and hands-on, but with no documentation or experience with this drivetrain it's definitely best for me to shut up and ask for help.  I'm NOT going to be attempting repairs on this bike myself, I just want to feel a little less blind and get some idea of what might be going on.

Thanks,
Ray

[ctrlburn]

When I had a "bad Thermistor" I found Bluetooth to actual being quite a bit off.
Unfortunately the problem deteriorated into contractor errors, and eventually failure to boot (unable to determine engine phase?), and resulted in engine replacement.
Partially attributed to early 2013 engine waterproofing methodologies.

Here is my test "problem" data.
"Temp" read on right flat face of motor IR thermometer (front of center).
"Ohms" readings taken pin 33 at Sevcom controller.
"Blue"tooth readings from Application.

After a test ride  - (which "limped" around 125 degrees):

Temp    Ohms    Blue
84        n/a       115
83        647       109
79        623        97

[rayivers]

Thanks very much!  I'll measure mine as soon as I can and report back.  I take it this thermistor is pretty well embedded in the motor and can't be replaced?

Ray