Speedo drive

General spannery stuff
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nickst4
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Speedo drive

Post by nickst4 »

Something my guru mentioned has just popped into my memory. He reckons that the speedo drive on Raptors (and presumably other bikes using this motor) is off the gearbox sprocket via the gizmo on the cover, and that's how the mph/km conversion is made, regardless of what the speedo readout calls the units. Thus mine has the right numbers but says they are kms. If this is true, it would also mean that you can't change the final-drive gearing without messing with the speedo.

Anyone know the facts? I'll have a look at the mechanicals later today...

Nick, UK
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Crap Tartan
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Re: Speedo drive

Post by Crap Tartan »

The speedo drive is from the little black gismo that bolts onto the gearbox sprocket casing. It sends a series of pulses every time the shaft rotates up to the speedo head.
I believe there are links inside the speedo head to change from MPH to KPH and vice versa. I am pretty sure the electronics in the speedo head determine how the speedo reads.
If you change the gear ratio by changing a sprocket from original then this will alter the accuracy of the speedo as the pulses relate to each rotation and not directly
to distance.
I dont believe there is an easy way to compensate for this but if you are just going up or down by the odd tooth then the overall percentage change should be minimal?
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nickst4
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Re: Speedo drive

Post by nickst4 »

Thanks, CT.

That's how I understood it from posts here, but my man seemed to think it was something mechanical, like a sprocket locking device with different numbers of lobes that the sensor would count for mph or kph. That ought to show up in a parts list if anyone has one. If and when I need to refresh the final drive, I might find out!

Cheers,

Nick
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Re: Speedo drive

Post by nickst4 »

nickst4 wrote:55 years agoThanks, CT.

That's how I understood it from posts here, but my man seemed to think it was something mechanical, like a sprocket locking device with different numbers of lobes that the sensor would count for mph or kph. That ought to show up in a parts list if anyone has one. If and when I need to refresh the final drive, I might find out!

Cheers,

Nick
OK, I couldn't resist looking! That plastic cover over the sprocket is located very precisely on two dowels, and it's easy to refit it wrong. Anyway, sure enough, there's a separate little gizmo with four lobes that's screwed to the gearbox shaft, and the sensor lies beside it and magnetically picks up pulses. This doesn't prove one way or the other as to how the kph to mph switch is done, but my man who worked at the importers says the lobed plate gets changed to suit the market. I'm inclined, therefore, to believe the speedo head just displays what it it told, and isn't itself adjustable. All good fun!

Nick
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Aussiejoe
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Re: Speedo drive

Post by Aussiejoe »

My 650 Raptor has the sensor on the rear brake disc, and one of the bolts is magnetised. The sensors are what is known as a hall effect sensor. My bike had been repaired after being put down on the left hand side and had a 1000cc speedo on it(the 650 one has a black face, the 1000 has a white face) and read about 40km/h when I was doing about 100km/h. I pointed this out after the test ride and they fitted a speedo healer on it to correct the problem. The 1000 speedo ended up failing(the tachometer still worked) so I got a 650 instrument panel but it was in mph, but with the speedo healer I just set it up to change it to km/h, and from my experience, any changes you want to make, using a speedo healer would be the simplest fix.
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Miz
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Re: Speedo drive

Post by Miz »

Hi, they all have 4 lobes for the sensor to pick-up on, there are links in the speedo to alter whether it is Mph or Kph, but they don't seem to be user friendly.

If you follow the wiring from your sensor to just behind the frame tube, you will find a little plug-in gizmo, if you remove this your speedo will report in Kph to match the display.

Something like this:-
http://www.ebay.co.uk/itm/fazer-600-kph ... SwOyJX8XIb
152/999
Image
Image
nickst4
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Re: Speedo drive

Post by nickst4 »

Miz,

Thanks for that. I was hoping to hear from someone in a km country who could comment on how many lobes that disc has, but what you describe makes more sense in terms of the likely mathematics. Seems my guru's memory got him to approximately the right area, and maybe I misunderstood him anyway.

I guess that raps it up! :)

Nick
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Re: Speedo drive

Post by ozzy »

for those reading this thread i thought i would add this.
when we brought a2nd hand 650 raptor from a main dealer the speedo was in kmh. we insisted it was changed to mph. in order to do this a new set of clocks were fitted. the dealer was very experienced. if it was a case of just changing or altering the sensor he would have as he was covering the cost as part of the sale.
secondly. these clocks recently burnt out a chip inside and speedo stopped. i had chip replaced and see clocks being bench tested. the bench test was not accurate speed wise, same bench test for any speedo, simply to see if sensor reading was being read and shown as a value which increased and decreased was test changed speeds. the bench test is the same equipment wither mph or kmh so it was my clocks that determined mph not the sensor
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