Suzuki GSX650F Forum - www.GSX650F.biz

Just wondering how accurate speedo is when using a GPS to compare?

I have noticed on my car that its spot on up till about 80kmph then slowly getts worse and worse the faster you go.

Lots of posts on this, search is your friend.

General consensus is that with the stock 15 tooth front sprocket it reads close to 10% higher than actual speed. With an aftermarket 16 tooth sprocket, reports are it's close to dead on.

Which is why I ride and add GST to my speed. Australian riders will get it

lol sort of thing an accountant would do just for fun.

seems weird that aftermarket product can improve it. i would of though it would be other way around

It's just a matter of sensor revs ratio. For some reason, Suzuki has decided to make the speedo read unnecessarily high. Annoying in particular (as I've mentioned elsewhere on this forum) because the odometer is more accurate using the same sensor. In any case, changing the sprocket ratio happens to correct it for the speedo, at the expense of odometer accuracy (but it's in your favor).

dont cars do same with speedo. think idea is its safer to think your going to fast than to slow when it comes to speeding fines.

Yes, and that's why the regs say you can err up to 10% upward and never downward. But as I detailed in another thread, the odometer is more accurate. It uses the same sensor. That's deliberately bad math.

Having read this thread, has anyone checked the accuracy of their own speedos and are they all about 10 % too high?

I checked my Speedo with my 2 GPS's and it was off 7% compared to both GPS's, that was at 70mph.

with my sprocket set up I was 22% high. Speedo healed back to dead on with my and my fiance's gps'eses

Noticed mine was about 5mph off. Haven't used my GPS yet, just noticed it while passing a car that had a digital speedo, where mine showed 67 theirs was 62.

I have my speedo healer set at 4% lower speed and this matches the gps pretty well with stock gearing. 110 kph is 6,000 rpm. When you go past a Roads and Traffic Authority radar sign, it gives you your speed, and so far my bikes speed matches the readout on the radar.

My bike was +8%, after going -8% with my SpeedoHealer 6000 Rpm is now 67 Mph not 73 Mph like it was out of the box.

(GPS in map window of tank bag)

I've never had a speedometer on a bike that was correct. 10% optimistic is very common. I think that every bike forum in the universe has at least a dozen threads on the topic.

Dave

Just got pulled over doing 79 in a 60. I'd say 10% is a touch hig, speedo claimed I was doing 85mph.

Worst part is my son was following me on his ninja, so we both are in hot water when my wife finds out! More so for me because I'm "corrupting our baby boy"!

Heads up to all of you -- sheriff indicated that state troopers have the right to class speeding 10+ over the limit as stunting (racing) if there are a couple of you together. Sheriff was really cool, let us off with a warning, and I've already slowed down a little