Yamaha PW-ST Motor Jerky

[E-bobby]

You have up and (half) down selection switches and a light switch so I would expect you to be able to replicate the test. If not find a newer version of the manual that has your display in the manual.

Half haha, yes I will try that now, I’ll look at the manual again and see if anything works. Cheers

 

[E-bobby]

You have up and (half) down selection switches and a light switch so I would expect you to be able to replicate the test. If not find a newer version of the manual that has your display in the manual.

I’ve managed to get to some mode it says d, think it’s the diagnostics but there’s a -1- and -2- etc until 4, then it says end after, what do I do on this, the manual isn’t very clear it says press the light button and it flashes for 0.2 seconds but it doesnt

 

[soundwave]

 

[E-bobby]

Hi, thanks for the video, I might actually need that because I have just found when I hold walk mode and hold the bike on the floor so it doesn’t move, then I hold the back wheel up it does around 2 crank spins without pulsing, but it’s got a rough wind what could this be? Maybe I need to take the motor apart and see if there’s anything binding because I’ve just put my ear on the keyhole so I could hear inside the frame and move the bike forward/backward you can hear something grating, that mode I was in doesn’t do anything. Please help!

 

[soundwave]

id just send it in and get it sorted

 

[E-bobby]

id just send it in and get it sorted

Thanks very much, if I can’t get to the bottom of it, then I will, I’m gonna take the motor apart tommorow and see if anything’s out of the ordinary. Cheers

 

[saneagle]

Hi just tried that but unfortunately didn’t work, I don’t have one of them function select switches on mine, here’s my display. Idk what else it could be. Thanks for your help

I'm no expert but that looks a bit broken to me!

 

[JoeCrow]

TBH, we all thought this was a classic case of a faulty speed sensor but as the replacement didn't fix it I believe it is long overdue for some expert troubleshooting at a good bike shop. They should have the expertise, tools and a readily available selection of spares to be able to find and fix the problem. I know it is always good to be able to resolve problems yourself but taking the motor apart could make things worse. If you have a good bike shop near you I'd use it!

 

[E-bobby]

I'm no expert but that looks a bit broken to me!

Yes, it’s broken but the buttons still work fine. Idk I’m no expert either clearly lol. Cheers

 

[E-bobby]

TBH, we all thought this was a classic case of a faulty speed sensor but as the replacement didn't fix it I believe it is long overdue for some expert troubleshooting at a good bike shop. They should have the expertise, tools and a readily available selection of spares to be able to find and fix the problem. I know it is always good to be able to resolve problems yourself but taking the motor apart could make things worse. If you have a good bike shop near you I'd use it!

You said yours needed a sensor, did you know that already or did you get them to troubleshoot? If so how much approx was it? Thanks. To be honest worst case scenario is a new motor and there’s one on eBay for 250 with under 100 miles on it, less powerful version but as long as it gets to 15mph it’s all good. Thanks joe

 

[saneagle]

Yes, it’s broken but the buttons still work fine. Idk I’m no expert either clearly lol. Cheers

There might be a crack letting water in. Did you check that?

 

[E-bobby]

There might be a crack letting water in. Did you check that?

No I didn’t to be honest, could it be the controller off of the symptoms? The 0kmph, flashing odo some motor power but then cuts out?

 

[soundwave]

the pcb is at the front so can get wet a why most fail but at least u can get every part for the motor

 

[E-bobby]

the pcb is at the front so can get wet a why most fail but at least u can get every part for the motor

Yeah, I’ll have a go at the motor tommorow, cabt really get any worse. Except from fully not working but basically isn’t now, thanks

 

[JoeCrow]

You said yours needed a sensor, did you know that already or did you get them to troubleshoot? If so how much approx was it? Thanks. To be honest worst case scenario is a new motor and there’s one on eBay for 250 with under 100 miles on it, less powerful version but as long as it gets to 15mph it’s all good. Thanks joe

The symptoms (similar to yours) on my wife's bike went away for a short time after I adjusted the magnet so it seemed likely the sensor had a problem (also an error code on the Bosch display, was speed sensor related). The bike was due for a service anyway so I took it in told them about the problem and asked them to fix it along with a service. They replaced the speed sensor and it has been good ever since. It was pricey, around 85 Euro from memory (just the speed sensor fix without the service charge) most of it labour, routing the cable through the frame, the sensor was cheap and they gave me the old one back.

 

[guerney]

If the display turns out to be borked by rain and not repairable, you could make a rain hat using clear plastic and self-amalgamating rubber tape for the new one, like I have? The plastic for yours would have to be more pliable than mine, for the buttons. I might make another rain hat for my button set, which is separate from the display, perhaps using a condom or some other pliable clear material, wrapped around the edges with self-amalgamating rubber tape.

 

[E-bobby]

The symptoms (similar to yours) on my wife's bike went away for a short time after I adjusted the magnet so it seemed likely the sensor had a problem (also an error code on the Bosch display, was speed sensor related). The bike was due for a service anyway so I took it in told them about the problem and asked them to fix it along with a service. They replaced the speed sensor and it has been good ever since. It was pricey, around 85 Euro from memory (just the speed sensor fix without the service charge) most of it labour, routing the cable through the frame, the sensor was cheap and they gave me the old one back.

Hmm, i might try to take it to a diagnostics and see what’s wrong, then I’ll probably be able to fix myself as long as it’s not the motor or something, yeah 88 personally I think its cheap as he just paid 45 pound for mine. Thanks for the reply!

 

[E-bobby]

If the display turns out to be borked by rain and not repairable, you could make a rain hat using clear plastic and self-amalgamating rubber tape for the new one, like I have? The plastic for yours would have to be more pliable than mine, for the buttons. I might make another rain hat for my button set, which is separate from the display, perhaps using a condom or some other pliable clear material, wrapped around the edges with self-amalgamating rubber tape.

View attachment 63818

That’s a good idea that, sort of like a screen protector on a phone but for rain. Yes I will definitely do that for my bike as they are 100 for them displays :-/ so dont wanna ruin that aha. Thanks for the tip and I’ll definitely be doing that once this issues sorted!

 

[E-bobby]

Update
Found a post on different forum. Will add link. People saying this has happened to them, exact same issue and speed sensor won’t fix, apparently there was a bad batch of Yamaha motors that had a software issue, most of them being bad after 300 miles, new motor fixed it. I’m not sure if this is what’s happening to me because I’m at 10k miles but could be possible. No recall on the motors either just left them. Motor issue pw-st

 

[soundwave]

how old is the motor new pcb and bearings be 500 quid