speedo still under reading

Well changed the plastic nut that runs the speed sensor yesterday,the one I took off didn't look particularly worn.took the bike for a run to check the the reading against my gps (garmin 660) speedo is still reading around 5-6 mph less than my actual speed,also the speedo seems a bit sluggish,not keen to fit a "speedo healer"as i think there is an actual fault somewhere any suggestions??

 

The only suggestion I have sounds like the one you don't want. All of our bikes have varying degrees of inaccuracy where the speedometer is involved. Factory issues, gearing, etc. all contribute to this. Unfortunately a speedo healer is the remedy. My ride is geared down a tooth in the front, exagerating the problem it already had from the factory. For me it's not the faulty speed reading that's bothersome, it's the faulty mileage that I worry about. I may be wrong but I'm betting, based on every other VFR out there, that that you don't have an issue with your speedometer. One thing you may want to try ( especially true if a bike is geared down ) is to measure the percentage of the inaccuracy at differant speeds. If you're off 5% at lower speeds (30 mph) and 10-15% off at higher speeds (90+ mph) than you know your dealing with a healthy speedometer and will in deed need a speedo healer to fix the problem. I know the extra expense is a pain in the ass, but over time, the affected and inaccurate mileage can can be seriously detrimental to re-sale.

I just re-read your post. I now see that you're reading lower than actuall, not higher. That changes everything. You may now take my post, wad it up, streak it, and discard in the nearest loo.

 

thanks for taking the time to reply anyway.

 

I'm not sure which model VFR you are having problems with, is it the 1999 or 2006 model? If its the 2006 model I'd take it back to the dealer and complain even if its out of warranty, my Honda dealer was very keen to please a former customer, and with luck they may be willing to try and identify the cause! I think the Vtec C-ABS models all use a digital sensor to work out the speed so it should not be too far wrong. Remember if its under-stating your true speed then it has the potential to get you into trouble. UK speed cameras tend to allow a little bit extra, but riding 5-6 MPH extra in a 30 limit could get you a speeding ticket. Add in the extra loading on your insurance renewal and it may make sense to invest in a speedo healer. Also when the bike needs its next MOT road-worthiness check this discrepancy will potentially be spotted by the tester and the bike failed. I think speedos are never allowed to understate the true speed and are only allowed to overstate the true speed by a maximum inaccuracy of 5%. so it sounds like you have a problem. Before reaching for the cheque book, its probably worth checking the tyre sizes and tyre pressures are right.

Good luck and let us know how you resolve the problem

 

yes it is the potential to be caught inadvertly speeding that is the problem especially as this country is overun with speed cameras,but since i am aware of the problem i adjust my speed accordingly and also can use my satnav to keep me straight.It not the expense of a speedo healer that is the problem,I dont want to buy one if there is something that can be fixed.

 

Jim,
I may have missed it on the other thread, but have you confirmed that you have the stock sprockets front and rear? It sounds like the bike was regreared to get better milage or a higher top end.

Action

 

Got the bike second hand so dont know if the sprockets have been changed,what makes me something is not right, is as I mentioned earlier the speedo seems sluggish and does not move till i am doing around 6mph.