contours Posted June 4, 2015 Share Posted June 4, 2015 I am new to the forum and my 2004 VFR800. I just changed the rear sprocket from 43 to 45 teeth and am very happy with the results. Since I don't have much experience with the performance of this bike, the speedometer readings seem a bit optimistic. Should I expect a change in sprockets to affect the speedometer? It seems to display about 7 to 10 MPH higher than it feels. I am accustomed to the speedometer error with my 2003 Triumph Daytona. This bike seems much, much smoother at speeds above 50 MPH than that bike. Thanks in advance! Peter Link to comment Share on other sites More sharing options...
Member Contributer Rice Posted June 4, 2015 Member Contributer Share Posted June 4, 2015 You have changed the final drive ratio, so yes, expect to see the normally optimistic speedo to become even more optimistic. I have the same setup and am used to assuming that I am travelling slower than it appears. Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 4, 2015 Member Contributer Share Posted June 4, 2015 Yes, changing sprocket sizes will affect speedo reading. There are a couple of aftermarket solutions to that which you can buy to correct the speedometer. Link to comment Share on other sites More sharing options...
Rich Posted June 4, 2015 Share Posted June 4, 2015 Yes, changing sprocket sizes will affect speedo reading. There are a couple of aftermarket solutions to that which you can buy to correct the speedometer. I read somewhere that if you correct the speedometer with a Speedohealer, that then the odometer (which was accurate stock) would be off. Maybe someone can confirm? Link to comment Share on other sites More sharing options...
contours Posted June 4, 2015 Author Share Posted June 4, 2015 Ahh - just as I suspected. I knew I wasn't going 70 MPH around that one sharp turn! I will be installing a device for my Daytona shortly. I guess I can check out what's available for the VFR800, too. Thanks much! Link to comment Share on other sites More sharing options...
contours Posted June 4, 2015 Author Share Posted June 4, 2015 It looks like the SpeedoDRD unit from 12oclockLabs I bought for my Daytona might work with the VFR800? Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted June 4, 2015 Member Contributer Share Posted June 4, 2015 It's changed by about 4.5%, or about 3 1/4 mph at actual 70. With stock gearing, my 6th gen's GPS measured 70mph is about 74 / 75 indicated so you'd likely be seeing 78 or so at an actual 70mph. Link to comment Share on other sites More sharing options...
RedRicer Posted June 4, 2015 Share Posted June 4, 2015 Does the speedometer have any relationship to the odometer as asked above? I'm considering changing my gearing but dont want my miles to be ticking up inaccurately. I know a guy who rigged up a wireless bicycle computer as an auxiliary speed/trip/odometer. i dont think thats a half bad idea. there's some pretty sleek little ones at REI you could stick somewhere easily. Link to comment Share on other sites More sharing options...
Baileyrock Posted June 4, 2015 Share Posted June 4, 2015 I think the stock speedo is off 7% (while the ODO is accurate) and your mod adds another 5-7% high. PS welcome to VFRD! BR Link to comment Share on other sites More sharing options...
Member Contributer YoshiHNS Posted June 4, 2015 Member Contributer Share Posted June 4, 2015 It looks like the SpeedoDRD unit from 12oclockLabs I bought for my Daytona might work with the VFR800? Another member here had one on his 4th gen. Not sure if he ever got it set right though, but he had it hooked up. You'll have to check the wiring or ask the manufacturer if they will directly swap. Link to comment Share on other sites More sharing options...
Member Contributer Conedodger Posted June 4, 2015 Member Contributer Share Posted June 4, 2015 The speedometer and odometer are tied to the same feed. As Bailyrock mentioned, "the stock speedo is off 7% (while the ODO is accurate.)" If you correct the speedometer, the odometer will be off. I chose to correct mine with a speedohealer. I have a spreadsheet for maintenance that has a correction factor built in for the mileage. Link to comment Share on other sites More sharing options...
Member Contributer The mailman Posted June 5, 2015 Member Contributer Share Posted June 5, 2015 I dropped two teeth up front on my '97 and only left it that way for a few short weeks. The speedo was SO far off and I was constantly trying to shift into 6th gear when I was already there. I didn't care for the high strung rpms even more than the overly optomistic speedo. Link to comment Share on other sites More sharing options...
TNRabbit Posted June 5, 2015 Share Posted June 5, 2015 An inexpensive option is to fit a wireless bicycle speedo Link to comment Share on other sites More sharing options...
Member Contributer mk3dub Posted June 5, 2015 Member Contributer Share Posted June 5, 2015 It looks like the SpeedoDRD unit from 12oclockLabs I bought for my Daytona might work with the VFR800? I'm using that product on my 03 with the same gearing as you. I want to say I calculated and measured an ~11.4% correction IIRC. My ODO is now about 8.5% low. Link to comment Share on other sites More sharing options...
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