Speedometer error - Sportbike Forum: Sportbike Motorcycle Forums
 
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post #1 of 8 (permalink) Old 08-08-2000, 04:40 AM Thread Starter
 
Join Date: Aug 2000
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This is my first post, so I first want to say HI to everyone here! Now onto my question for you guys. I just bought my bike a few weeks ago, and I just love it. It it a 1997 Honda CBR600F3. Full Micron exhaust with matching stage III jet kit, tank bra, seat change, tinted windshield, etc. Unfortunetly, the guy who did this work was the first owner.....i am the third owner. So i don't exactly know everything that was done. Well, yesterday i was riding next to my girlfriend (she was in her car), and later she said, "why were you only doing 50mph?" well, i knkow my speedo said about 60mph when i was on that road. so i am wondering if the guy changed the gearing???? Is that an indication of that? What else could it be, and can the speedometer be calibrated? Thanks for your help guys.

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F3 Rocket is offline  
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post #2 of 8 (permalink) Old 08-08-2000, 05:10 AM
 
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Lightbulb

F# Rocket, are your sprockets stock? How many miles does the bike have? Somebody could have changed the gearing. Lower gearing to increase acceleration will yield a speedometer error similar to what you are seeing.

You can calibrate your speedometer easily using a stop watch and some interstate highway with mile markers. Travel at an indicated 60 or as close as possible for several miles, the more the better. Divide the seconds by the number of miles. Take that number and divide it into 1 to get miles per second and multiply by 3600 to get miles per hour. Just try and find somewhere to mount the stop watch on your handle bars.

Good luck,
NCVFR

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post #3 of 8 (permalink) Old 08-08-2000, 05:43 AM Thread Starter
 
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The bike has 5200 miles on it. It is my first bike, so I am not all that familiar with what the stock sproket would look like. Is there anyway I can easily find out by looking at it? There is a good chance it was changed, cause the entire bike seems to be modified. I understand what you are saying about how to find out how accurate the speedo is, but how do you actually change it so that it is correct. Is there an ajusting screw or anything at all to do this? Sorry for all the questions, just don't know enough about bikes yet. Thanks for your help, it is greatly appreciated.

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F3 Rocket is offline  
 
post #4 of 8 (permalink) Old 08-08-2000, 05:43 AM
 
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From what I have read honda speedo's are known for being off (Usually to the optimistic side). I mounted a Sigma bc1200 on my '00 F4 and with stock gearing the factory speedo was about 5% off at 50. I then dropped 1 tooth on the front sprocket and it went to a little over 10% off at 50. It now reads about ~56mph when the Sigma reads 50mph. The Sigma is getting it's speed from the front wheel so gearing does not affect it. If you want an accurate speedo I would suggest this.

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'00 F4
'00F4 is offline  
post #5 of 8 (permalink) Old 08-08-2000, 06:45 AM
 
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I agree with 00F4 the best way to get an accurate speedo is buy a bicycle one. I am not aware of anyway to adjust your speedo. If it is like the VFR it is driven off the primary drive shaft and is affected by any gearing changes, including tires. Generally motorcycle speedo all read slow, mine is about 3%.

Good luck,
NCVFR

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NCVFR is offline  
post #6 of 8 (permalink) Old 08-11-2000, 10:43 AM
 
Join Date: Apr 2000
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I had a '95 F3, and the speedometer was off about as much as yours it. It had stock sprockets and all. When I was going 55, the speedo said 65. I just learned to do the math in my head.

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CBR_Damon is offline  
post #7 of 8 (permalink) Old 08-12-2000, 06:39 AM
 
Join Date: Dec 1999
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Question

Here`s another speedo question.My TLR reads speed from the countershaft sprocket(I think its done by magnets).How much more accurate is this measurement than the traditional method?(speed measured from the front wheel).

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auger is offline  
post #8 of 8 (permalink) Old 08-15-2000, 01:24 AM
 
Join Date: Feb 2000
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Only good for certain bikes. TLR is one of them. Haven't tried it yet, but will be very soon.
http://centauri.ezy.net.au/~fastvid/

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sean is offline  
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