Help with my trike

[Headshok]

Hi I have just picked up a used Kentex E trike, 36V and 250W front hub motor.

the trottle works fine so I know the motor and wiring are ok, BUT.....

When I use it in pedal assist mode I am only getting power when the right hand crank is between 90 and 180 degrees.

on close inspection the "crank disc" is not spinning true against the pick up.

For example the gap is <1mm in the 90 deg range I am getting power and >3mm for the other 270 deg? I assume this is why I am not getting smooth constant assistance?

What should the gap be and can I "bend" the crank disc back into shape - I am not sure if it is metal or plastic?

PS there is no "play" in the BB at all and I dont think it has done many miles -

 

[wheeliepete]

Working gap can vary, but 1-2mm is usually best, even all the way round. It looks like your disc has been modified and glued to fit the 1 piece crank. It's plastic, so will bend, but you may find the glue will break when you do. A hot air gun or hair dryer might help.

 

[Headshok]

wow what a crap design- its a piece of brittle plastic thats glued on!

And this was causing my lack of power on the 270deg of the cranks - so now I am investigating if the miss alignment is from the shoulder it sits on or itself and as I can see some of the crank thread I will try and find some to snug it up instead of being glued in place!

 

[Headshok]

cheers I have removed it and there is a crack in it., so I will see if I can fit another crank and BB it as I have a spare Square/Octalink and External cranks - so any recommendations please for a new magnet disc for these cranks?

 

[wheeliepete]

This 12 magnet disc will replace yours.

https://www.ebay.co.uk/itm/Electric-Bike-12-Magnet-PAS-Pedal-Assist-Sensor-Cadence-Speed-Ebike/272483488897?epid=813781908&hash=item3f71481481:g:3HsAAOSw3hBZyl0A:rk:7:pf:1

 

[jokskot]

..... or this at less than a fifth of the price quoted for the item identified by wheelie pete

https://www.ebay.co.uk/itm/PAS-System-E-bike-Electric-Bicycle-Scooter-Pedal-Assist-Sensor-5-12-Magnet-Type-/273550998837?var=&hash=item3fb0e8fd35

 

[Nealh]

The 12 pole disc will give smoother pas pick up, also depending on the controller an inferior disc pole count may not work unless the controllers parameters can be changed.
The 12 pole version isn't available on the cheap listing.

 

[Headshok]

i like one in westbury, same county as me, what type of Bottom bracket/cranks is it designed for.

Something is flexing or my 12 magnet disc is faulty as I have a power cut for about 40% of the rotation. My sensor looks a bit naff also.