Boov Posted May 22, 2009 Share Posted May 22, 2009 I put a 18T sprocket on my bike and the speedometer is virtually perfect. I assume the pickup for it is somewhere on the final drive side of the transmission. Is this the pickup for the odometer as well? I want some accurate milage recording for a trip. Quote Link to comment Share on other sites More sharing options...
RXX Posted May 22, 2009 Share Posted May 22, 2009 Do you have a GPS? Quote Link to comment Share on other sites More sharing options...
Boov Posted May 22, 2009 Author Share Posted May 22, 2009 Do you have a GPS? Yes I do. I'm just curious how the instrumentation ties into the driveline. My XX is my first bike that didn't have the speedo come off the front tire. Quote Link to comment Share on other sites More sharing options...
RXX Posted May 22, 2009 Share Posted May 22, 2009 Do you have a GPS? Yes I do. I'm just curious how the instrumentation ties into the driveline. My XX is my first bike that didn't have the speedo come off the front tire. OK, sorry, I didn't understand the phrasing I guess. There is a sensor on top of the transmission that counts pulses from some shaft. I think it uses the Hall effect. I have not been able to find out how many pulses per mile the BB generates. Quote Link to comment Share on other sites More sharing options...
jon haney Posted May 22, 2009 Share Posted May 22, 2009 Do you have a GPS? Yes I do. I'm just curious how the instrumentation ties into the driveline. My XX is my first bike that didn't have the speedo come off the front tire. OK, sorry, I didn't understand the phrasing I guess. There is a sensor on top of the transmission that counts pulses from some shaft. I think it uses the Hall effect. I have not been able to find out how many pulses per mile the BB generates. IIRC the sensor reads on 2nd or 3rd gear (I know it has 28 teeth). If you can calculate the number of output shaft rotations for top gear in one mile, just multiply that by 28. I had to program my data logger on my drag bike with this info so I could read wheel speed. It is almost dead nuts on when compared to the trap speeds on my time slips. Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted May 22, 2009 Share Posted May 22, 2009 Your 18t front sprocket brings the speedo very close to dead on. Unfortunately, the odometer is essentially correct with the 17t sprocket...just to underscore the purposeful error built into the speedo circuit. So with the 18th you'll find that its no longer so far to grandma's house, and your gas mileage has gone all to shite....at least according to the odometer. Quote Link to comment Share on other sites More sharing options...
Boov Posted May 22, 2009 Author Share Posted May 22, 2009 Your 18t front sprocket brings the speedo very close to dead on. Unfortunately, the odometer is essentially correct with the 17t sprocket...just to underscore the purposeful error built into the speedo circuit. So with the 18th you'll find that its no longer so far to grandma's house, and your gas mileage has gone all to shite....at least according to the odometer. I was trying to figure out what happed to my mileage... Thanks! Quote Link to comment Share on other sites More sharing options...
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