125cc Sportsbikes Forum banner
1 - 16 of 16 Posts

·
Registered
Joined
·
1,388 Posts
Discussion Starter · #1 ·
Right out for a ride this afternoon and I went over a bump in the road a little too hard, i think its given something a nasty knock, as the speed on the screen went to 0mph. and stayed there. First of it a 59 plate, so still in warranty, I'm debating on just leaving it overnight to see if the ecu just wants to re set itself.

On the way back the speed started working again, but fluctuating, 20, 10, 50, 40, 6, etc and when at a stop, it sits at 3mph for a few seconds before getting down to zero, Got home, left it for 30 mins, and took it for spin down the road, and I can't trust the speed on it. Untill i got into 5th around 70 it seemed to get more accurate (what im used to it like when the speed was showing right).

So i got my wiring diagram out and found out the plug on the cdi, took it out and had a look didn't see anything out of the ordinary, took the speed sensor out and there was no knocks or dents in it.

Just want to get a few ideas, wether its worth leaving it over night, or put it in the garage (as under warranty) or get my multimeter out and start probing. Its an inductive sensor iirc.

Ideaaaas??
 

·
Registered
Joined
·
1,403 Posts
warrenty ... nothing more to say
 

·
Registered
Joined
·
1,388 Posts
Discussion Starter · #3 ·
can't get it to garage untill during week, so i need something to look at incase I can solve it.
 

·
Registered
Joined
·
4,954 Posts
the speedo sensors are a common fault in the new shape rs125s. Mine went and other members have spoken of theirs just randomly... stopping.

I dont understand why people would start probing their bike when someone else will do it for free lol. You can still ride it in the mean time so just get it looked at by aprilia
 

·
Registered
Joined
·
1,388 Posts
the speedo sensors are a common fault in the new shape rs125s. Mine went and other members have spoken of theirs just randomly... stopping.

I dont understand why people would start probing their bike when someone else will do it for free lol. You can still ride it in the mean time so just get it looked at by aprilia
ah right thats a little better then, job for the warranty, and Im a mechanic i like to see how it all goes apart and comes back together im weird like that i enjoy fault finding, its a shame i don't have the room for a project bike that would be ideal.
so i wanted to look to see if i could fault find if anything was up. definately taking it for aprilia to have a look in the week, just wanted to know if there was anything i could do to fiddle with.

Yeah I rode it about coming home, its only the sensor i know. lol wanted to know if anyone elses had had a knock before and had the same issue.
 

·
Registered
Joined
·
3,963 Posts
on my newshape rs50 all those years ago i hit a bump pulled over and the speedo read like 97, 50, 42, 28, 111 then back to 0, was a proper WTF? moment was ok after though
 

·
Registered
Joined
·
4,954 Posts
ah right thats a little better then, job for the warranty, and Im a mechanic i like to see how it all goes apart and comes back together im weird like that i enjoy fault finding, its a shame i don't have the room for a project bike that would be ideal.
so i wanted to look to see if i could fault find if anything was up. definately taking it for aprilia to have a look in the week, just wanted to know if there was anything i could do to fiddle with.

Yeah I rode it about coming home, its only the sensor i know. lol wanted to know if anyone elses had had a knock before and had the same issue.
the main worry I would have is them refusing to fix it becuase it has been 'tampered' with. (b*st*rds would say anything to avoid a repair)

the bump is probably coincidental. Tbh looking back. I don't understand how the hell those sensors work lol
 

·
Registered
Joined
·
2,724 Posts
the speed sensor works the same as a cycle computer. the rear brake has 1 or more magnetic bolts to trigger the relay in the sensor as the wheel rotates.
these pulses are sent to the CDI (the 3 pin plug) the middle wire (pin 2) is the one the pulse is sent through.
after the CDI has done what it needs to do with this pulse info it is sent to the clocks via pin 8 of the CDI to pin 13 on the clocks.




p.s This is for a n 07 euro3 model it may be the same for other models but can't confirm this.
 

·
Registered
Joined
·
4,954 Posts
I thought just after leaving that post it could be magnetic. So does it count how often the magnetic bolt comes around and then the ecu does the maths to work out the speed?
 

·
Does not know Everything !
Joined
·
14,526 Posts
So does it count how often the magnetic bolt comes around and then the ecu does the maths to work out the speed?
yes, all it does is count the time between passes of the sensor iirc.
 

·
Registered
Joined
·
1,388 Posts
OP has it right,and xtreamer same wiring diagam as the one i have, its an inductive sensor so it has a coil inside it which creates a magnetic force, which can pick up on the spots on the rear brake disc, whether it be inside the disk, or bolts, caculation how many times it picks the signal up, it can tell the ecu roughly how fast the wheel is turning, its the same principle with a tdc sensor on a car.
 

·
Registered
Joined
·
2,724 Posts
OP has it right,and xtreamer same wiring diagam as the one i have, its an inductive sensor so it has a coil inside it which creates a magnetic force, which can pick up on the spots on the rear brake disc, whether it be inside the disk, or bolts, caculation how many times it picks the signal up, it can tell the ecu roughly how fast the wheel is turning, its the same principle with a tdc sensor on a car.
yeah, not relay
i ment read switch.
i'm sure its the bolt/s that it counts same as the rsv.
 
1 - 16 of 16 Posts
Top