bike want s to go

garysnooker

Pedelecer
Sep 10, 2020
122
3
when i switch the bike on it some times lunges forward this as happend 3 or 4 times i made sure the pedals did not move on the bike before i switch on
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,990
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West Sx RH
Does it have a throttle fitted ?
 

Cancunia

Pedelecer
Aug 6, 2021
52
8
Try holding on one of the brakes when you switch on. The brake sensor should stop the surge, but if it doesn't, the brake will help.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
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Basildon
Can you be more specific about when it happens. There's no logical way it can do it just by switching on. Do you have to touch something first or move the bike? What sets it off?
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,642
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Winchester
Try holding on one of the brakes when you switch on. The brake sensor should stop the surge, but if it doesn't, the brake will help.
i did try that but i got a error on the display
On our (different, XF07) machine you get an error if you hold the brakes during switch on, but it goes away when you release the brakes. You could try that. It may well not work on yours, and if it does you may still get a surge, just delayed till you release the brakes and the electrics kicks in.

Can you be more specific about when it happens. There's no logical way it can do it just by switching on. Do you have to touch something first or move the bike? What sets it off?
I guess that could happen if the throttle is independent from the PAS and the throttle is not properly returning to the off position.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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Disconnect the throttle and switch on, if no surge then you will have a wire fault likely on the throttle signal line. The fault is likely a broken or intermittent wire contact, wet has got into the throttle or could be bridging a pair of pins if a waterproof connector.

There are only two options for the bike to lurch and that is PAS or throttle these are the only two drive systems.
 

vfr400

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Jun 12, 2011
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I guess that could happen if the throttle is independent from the PAS and the throttle is not properly returning to the off position.
It can't happen. The controller won't give power after switching on until it sees a zero thottle situation. It's a safety feature to stop what OP is describing. We need more info instead of making wild and incorrect guesses.
 
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vfr400

Esteemed Pedelecer
Jun 12, 2011
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Try holding on one of the brakes when you switch on. The brake sensor should stop the surge, but if it doesn't, the brake will help.
The controller also checks the brke switches at startup. If a switch is on, it'll give an error code.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
19,990
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West Sx RH
Perhaps disconnect the throttle & PAS from the controller & then see if it surges?
It won't the controller needs an input signal for it to do so, so either one from PAS or throttle. The obvious and most likely one to cause an issue is the throttle.