Help diagnose a Tongsheng problem?

[jellyfish61]

I have a quite new (900-miles) TSDZ2 running perfectly (stock firmware) except that very randomly, pedals get disengaged (chain not moving). When this happens, if I hit the throttle for 1-2 seconds, the chain immediately restarts and I can pedal again with the normal assist. No strange noises, or grinding etc. Then it might happen again maybe one hour or ten minutes later (or not at all).

I was wondering if this could be either a blue gear or sprag clutch issue or maybe something else? I would like to order the right part before opening the motor.

 

[stratohunter]

Are you getting slips when pedaling, like crank turns but chainring doesn't? This indicates the sprag clutch needs a replacement.

Or are you randomly having pauses of output power? If this is the case, do you still hear the motor when the chainring stops? If the inside motor still turns but your chainring doesn't, it's likely the one-way bearing inside the blue gear. If the inside motor pauses then I'd check for a loose connection.

 

[jellyfish61]

I spin the pedals but the chain won't move, to be honest this motor is so silent I didn't notice if it stops spinning.
What I don't understand is why if I hit the throttle just one sec, the chain moves again and pedaling also works.

 

[endlessolli]

I spin the pedals but the chain won't move, to be honest this motor is so silent I didn't notice if it stops spinning.
What I don't understand is why if I hit the throttle just one sec, the chain moves again and pedaling also works.

This indicates a worn sprag clutch unfortunately. This is a $30 std part (CK30P), but you need a tool to press it into the main gear. Or you buy a new main gear which includes that clutch already. Thats around 100$
Note: This thing wearing out after only 900 miles is unusual. Are you standing often with your full weight on the pedals while in a high gear? That overloads the clutch

 

[jellyfish61]

No I never stand on the pedals and also I've been treating the bike (motor) very gently since I got it (although it is extremely hilly where I live).
Today I've gone for a 60 mins ride and it's happened only once!
I don't have a bearing press, is this the entire part? $30 not so expensive.
https://www.pswpower.com/products/p...for-tsdz2-electric-bicycle-central-mid-motor-

 

[endlessolli]

Yes; thats it (30$ is cheap! I renembered it being more expensive)
The are 2 Versions: Straight (older version) and helical gear ( newer version). You need to check which one you currently have to order the correct one.