ERider 8000W scooter - Australia (similar to xm5000li)

Thanks a lot Phil for the encouragement, the CA-Details and the little video! It DOES sound different now, indeed no more low speed groaning, but a rather high pitched whine. And initial acceleration was really tired, or was your hand being gentle to the throttle? What I find rather distrubing about this high-tech Sevcon and it's PDT governing is that regen rocking back and forth once the wheel has come to a stop. To me it appears as if something had been overlooked in the controller programming. The Kellys continually reduce regen current when approaching standstill and call it their "anti-lock" function. On the stand regen simply brakes the wheel to standstill, and that's it, standstill. Oh well, probably this does not pose any problem in everyday use...

As for cutting cables, as long as I have warantee on my bike I won't even think about such acts of intentional vandalism on the main artery of my bike :-) But AFTER those two years...

Ah, O.K. then. With mine it takes maybe 1.5 seconds from 0 to idle max rpm at full blast on the stand.
What causes that high-pitched whine, I wonder? As the frequency of the whine changes with rpm it cannot be power PWM which will normally operate at constant frequency, no matter what the rpm.
Maybe it is simply the commutation sound, and it comes out as a single dominant frequency with the Sevcon because it approximates a sine wave, wheras my Kelly Trapezoid is so infested with higher pitch overtones that the basic commutation frequency is masked by all those higher notes that make up the groaning noise at lower RPM?

Thanks Phil, most of that is absolutely clear to me :-) Wherever you have a coil through which alternating current flows, and some magnets opposite them, you have a kind of loudspeaker. The rotary solenoids ("torquer") we use to drive our EGR-valves (that is at my work) are quite efficient loudspeakers, and with the dawn of the more quiet common rail fuel injection in modern Diesel engines our 4kHz power PWM driving the torquers produced a whine audible even with the engine running. By chance we had hit the resonance frequency of the rotor :-)
A slight frequency change dimmed the squeak to acceptable levels again.
My Kelly reportedly uses 16.6kHz power PWM, which is beyond my around 13kHz hearing limit already. I have no idea what the Sevcons use, but that high pitched and rpm-variable whine from your motor should have nothing to with the controller frequency, but rather with the commutation, or so I suspect. We have a fair amount of pole pairs spread around our rear wheel rims, so it could well be the commutation itself that makes that sound? Some 28 pole pairs it should be. Multiply that by 1000rpm and divide by 60 yields a possible base frequency of 467Hz, which is definitely not that high-pitched whine. And I doubt that the controller MOSFET's would be so loud, but who knows???

As the forum did not register my reply properly I will try again to get it registered as a new post :-)

PCarlson, I was trying to think if I ever tightened my axle nuts, and of course I did....I had a flat on my rear tire and completely removed it and reinstalled. I remember using a very large wrench to tighten it back as tight as it was and making sure that both axle bolts were as "far up" as they could go so the tire would be in alignment with the bike. Not sure if that helps? It sounds to me like one of your axle bolts is not completely in its holder. I did not have any wobble afterwards, even with the new larger tire. 7939 miles and counting....

Latest word from Mountain Chen, one more month before the 72V BMS is ready for production....

Yes I'll be happy with a BMS on this bike. I also heard from eRider that two more bikes may be sold in Canberra :-) that means we won't be the only ones! Cool.

After talking with eRider and PDT and me pulling apart the bike and testing. We have worked out the problem with the stiff steering. Talk about service! ERider has posted the new part.

Which part was broken?

Oh oh, the steering head and steering bearing. If that is broken riding is outright life-threatening!!! Keep the bike sitting nicely on your porch until replacement comes...
And then comes the "fun" part, because adjusting the slack/tightness of this bearing is about the most tricky job on any motorcycle to get right, and in particular on our Chinese bikes, where it quickly becomes a safety relevant issue with judders and shimmys of all sorts hiding in those bearings, just waiting to pounce on you when you least expect them... I'm wishing you heaps of patience to get that just right :-)

Phil, are your tricks sharable? It would help a lot of folks (including me as I will probably have to care for my bike myself in the near future without my local dealer...) here to get to know some helpful tricks of the trade for this VERY crucial adjustment job :-)

Finally the temperature here in Sweden is above 10C, so yesterday I woke the scooter up from winter hybernation and took it out for a ride.
Wonderful!

Been riding today as well and noticed that the the battery voltage dips less after a couple of "wake up" cycles.

That's great news Johnny. Remind me again, are you using CHL 50Ah cells? I can't remember

Yes! (waiting for the BMS aswell...)

Thanks Phil for the explanation! To feel if I have play in the steering head I have put myself in a sort of trance, sitting on the ground in front of the front wheel with the bike on center stand. Then I grab hold of the front axle with both hands and gently begin to rock it back and forwards. Big play will be felt quickly, but when there is not much, that is were the trance part begins :-) Closing my eyes I can eventually feel even the slightest play in the head bearing.
The tightening itself I have not done myself yet, as I lack the appropriate tooling, but I would think the hardest part is finding the right spot for the main nut, so that when it is countered the play is as should be?

Was the original bearing greased? If so I would have been very hesitant to replace it with another Chinese bearing from the same manufacturer.

The "about $12" spanner I ordered from Sears (cost with shipping and a discount from an online sale: about $35) should be here tomorrow, so I will be tackling my own possible steering head issues this weak. If I find a destroyed bearing, I won't be replacing it. Hopefully it just needs to be tightened. Maybe once I'm finished with it I'll pass it around the group, as it appears this tool will be widely needed.

Rather than do a separate post in an obscure topic: I'm still looking for a return spring for my XM-3000's front caliper. A whole caliper assembly would also be an option, if no more than $50 shipped.

Boy oh boy, that looks BAD!!! Almost as bad as the complete wreck of a former steering head bearing from my old ICE Aprilia Scooter. Good thing you now a fresh set of whatever bearings up front! But if they fail again after a similar time I would also propose to look for higher quality replacment parts!

I believe you have mentioned that your wife is considerably lighter than you. That could be the only reason her steering bearing hasn't yet failed. The Chinese (like the Japanese earlier on, only worse) tend to design things for people the size and weight of an average Chinese person. She probably also rides a little less aggressively on average than you do.

I think the problem is that they haven´t tightened it properly in the factory causing uneven, extra heavy wear.

I got my Cycle Analyst today by the way! Just waiting for the "old passive" BMS from Mountain.

I believe you have mentioned that your wife is considerably lighter than you. That could be the only reason her steering bearing hasn't yet failed. The Chinese (like the Japanese earlier on, only worse) tend to design things for people the size and weight of an average Chinese person. She probably also rides a little less aggressively on average than you do.

Yes she is a lot lighter than me but as for aggressiveness, she wins there! I'm a slower driver, she's a speed demon!

I now have around 5600km, she only has 1200km I think.

So we won't know for a while if these scooters all have inadequate bearings.