Guest Splinter Posted June 7, 2010 Share Posted June 7, 2010 Hello! First off great forum I am really enjoying reading through all the material here great knowledge base. So I thought I would put it to good use, I have a 1995 VFR 750, I have brought it back to life from a bike that had been sat in a barn for 3 years, I am on my final hurdle. I took the bike off to be MOT tested here in the UK and noticed the speedo was not working. After a lot of head scratching I think based on the minimal voltage coming back from the speed sensor it is this that is playing up! (its not the plastic connector that attaches to the sprocket either). I am struggling to locate one for my generation of bike however I noticed there are plenty for the vfr 800 Fi and was wondering if anyone knew if it was the same sensor? as it looks identical. Also what sort of fluctuating voltage should I be reading from the sensor as mine was giving out a max of 0.017v Thanks in advance Francis Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted June 8, 2010 Member Contributer Share Posted June 8, 2010 there is no voltage to check.. its a mechanical unit.. .. you say its not the white plastic part.. ..the perfect plastic has a slot on the back.. that gets rounded out.. if thats not the problem.. the cable may be broken. Link to comment Share on other sites More sharing options...
SEBSPEED Posted June 8, 2010 Share Posted June 8, 2010 there is no voltage to check.. its a mechanical unit.. .. you say its not the white plastic part.. ..the perfect plastic has a slot on the back.. that gets rounded out.. if thats not the problem.. the cable may be broken. Greg, 90-93 was mechanical, 94-97 has an electronic pickup just like the newer gens. The part of the white plastic nut that gets rounded off is usually the hex side, the side that mates with the countershaft sprocket bolt. To the original poster, it could be as simple as checking the part numbers online for both units(yours & the newer model) to see if they would be compatible. You might also try downloading the service manual from our links section to find a testing method. Good luck! Link to comment Share on other sites More sharing options...
FinnRC36 Posted June 8, 2010 Share Posted June 8, 2010 Hello! First off great forum I am really enjoying reading through all the material here great knowledge base. So I thought I would put it to good use, I have a 1995 VFR 750, I have brought it back to life from a bike that had been sat in a barn for 3 years, I am on my final hurdle. I took the bike off to be MOT tested here in the UK and noticed the speedo was not working. After a lot of head scratching I think based on the minimal voltage coming back from the speed sensor it is this that is playing up! (its not the plastic connector that attaches to the sprocket either). I am struggling to locate one for my generation of bike however I noticed there are plenty for the vfr 800 Fi and was wondering if anyone knew if it was the same sensor? as it looks identical. Also what sort of fluctuating voltage should I be reading from the sensor as mine was giving out a max of 0.017v Thanks in advance Francis The difference between the VFR750 sensor and VFR800Fi is that the VFR750 unit produces 5V pulses and the VFR800 unit 12V pulses. I know this since I put the VFR800 unit to my 3rd gen bike to run an electric speedo. Either would have been good to me but since I needed 5V pulses I had to use a 5V feed voltage for the VFR800 pulse sensor to get 5V pulse output. Luckily my Koso gauges had the desired 5V output for the speed sensor. Just had to do some splicing and soldering of wires. Link to comment Share on other sites More sharing options...
Member Contributer tdchonda1 Posted June 8, 2010 Member Contributer Share Posted June 8, 2010 Hello! First off great forum I am really enjoying reading through all the material here great knowledge base. So I thought I would put it to good use, I have a 1995 VFR 750, I have brought it back to life from a bike that had been sat in a barn for 3 years, I am on my final hurdle. I took the bike off to be MOT tested here in the UK and noticed the speedo was not working. After a lot of head scratching I think based on the minimal voltage coming back from the speed sensor it is this that is playing up! (its not the plastic connector that attaches to the sprocket either). I am struggling to locate one for my generation of bike however I noticed there are plenty for the vfr 800 Fi and was wondering if anyone knew if it was the same sensor? as it looks identical. Also what sort of fluctuating voltage should I be reading from the sensor as mine was giving out a max of 0.017v Thanks in advance Francis I think I have a good used one I took off my 95. If interested shoot me a PM. and welcome to VFRD. Lots of great info here and everyone is very helpful. Enjoy your ride! Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted June 10, 2010 Member Contributer Share Posted June 10, 2010 there is no voltage to check.. its a mechanical unit.. .. you say its not the white plastic part.. ..the perfect plastic has a slot on the back.. that gets rounded out.. if thats not the problem.. the cable may be broken. Greg, 90-93 was mechanical, 94-97 has an electronic pickup just like the newer gens. The part of the white plastic nut that gets rounded off is usually the hex side, the side that mates with the countershaft sprocket bolt. To the original poster, it could be as simple as checking the part numbers online for both units(yours & the newer model) to see if they would be compatible. You might also try downloading the service manual from our links section to find a testing method. Good luck! hhhmmm odd.. i have never seen the white plastic drive part stripped on the hex.. always on the other sides slot... my pals 96 keeps being stuck in brian.. i forgot he put a mechanical one on his.. so solly! :laughing6-hehe: :biggrin: Link to comment Share on other sites More sharing options...
Guest beachbloke Posted August 4, 2011 Share Posted August 4, 2011 Interesting topic, I'm having a similar problem. I just bought back a bike I used to own because I knew it's history. Anyway on the way down to my place the reg/rec failed and eventually the bike cut, out and the guy had to be recovered. He's covered the cost of a new MOSFET reg/rec and a new battery, but I also found that all the bulbs had blown and the speedo wasn't working - presumably all due to the voltage spike when the reg/reg went. I've downloaded the maintenance manual and checked the speedo sensor and according to that the sensor is kaput. If I understand correctly I should be seeing an on-off 5v between the green and pink wires at the sensor and I'm not. So in theory it's dead. ***Can anyone confirm that the input voltage to the sensor (black wire) should be 12v, and the output (at the pink wire) is 5v? Or should the sensor be getting a 5v supply somehow? Mine is seeing 12v at the sensor connector*** Interestingly I've I connected my meter across the black and pink wires and when I do that I get a square wave at 0-12v. Not sure if that's relevant anyhow..... So I've ordered a new sensor from the dealer - £168 - holy cow!!! But I'm nervous. What if something in the speedo has been damaged and when I plug my new 'more expensive than gold' sensor it gets fried? Can't imagine the dealer being sympathetic. Anyone any experience with this? I've done some maths and I estimate that at 80km/h (my bike is an import with kph clocks) the frequency of the 0-5v signal should be around 360Hz. So my current next plan is to rig the speedo up to a signal generator, run a 0-5v 360Hz signal through it and see if the needle gets to ~80kph. Any help / experience greatly appreciated. Oh and this is my first ever post. Great forum! Link to comment Share on other sites More sharing options...
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