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How can running from the engine increase the accuracy of a speedo? Speedo is representing the distance covered in a certain period of time... I can not see how the engine can improve accuracy of a speedo - after all the engine itself has no way of determining the distance being covered. The most extreme example I can think of is remove the chain on the bike - the engine can be running like crazy, but you aren't going anywhere. I may be ignorant in regards to my logic here though...

I had a max of 167 kph (indicated) on my old fzr (but had about 3500 revs left to go). Have heard of people reaching 200...

Other speedo innacuracies: Tires can also change indicated speed - a new tire (one that isn't worn) can actually have an actual speed of 4 kph greater than a tire worn tire at 100 kph despite both having an indicated speed of 100 kph. (So already if you double this to 200, then the speedo can be out by as much as 8kph just by tread depth). And finally, most speedos are not precise (as you suggested). Within Aus speedo's only have to be within 10% of the speed being travelled at from 0-100 kph. They are not calibrated for speeds over 100 kph. A good example are r1's - they supposedly read about 30 kph over when reaching speeds around 250 (indicated).

 

If you want to measure your true speed, borrow or buy a GPS. My one registers amongst other things, maximum speed. <!-- s:o --><img src="{SMILIES_PATH}/icon_surprised.gif" alt=":o" title="Surprised" /><!-- s:o -->)) So far, I've seen 103mph, but was coming up to a round-a-bout so I ran out of road.

 

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Cmon Boz surely u can see the logic, lol. Engines gotta be more accurate than the wheel when measuring distance. <!-- s:shock: --><img src="{SMILIES_PATH}/icon_eek.gif" alt=":shock:" title="Shocked" /><!-- s:shock: -->

I reckon the best way would be one of those g force meters. Heard they are pretty accurate. Not sure about gps though...sounds alright I guess..but they prob aint designed for much accuracy. Im sure they would prob be better than measuring it off the wheels (or engine lol). As boz said there are a fair amount of variables involved.

And as for top speed..I had my old one prob up to only 170...Im guessing down a slight incline..they might make 180-190...

 

I'd have to agree with Boz. Here in the states, when the local police check a morot vehicle accident, they pull out a distance measuring device which is a bicycle tire with a meter on it.

GPS is done by triangulation and works pretty well. It measures time over distance and does the calculation. Pretty accurate, but not as.

 

I am not sure that the g-tech meters measure top speed? I might be wrong tho. Just type gtech into ebay and it will come up with a bunch of different ones.

 

I've tested it against a local speed sign that tells you your speed by a little radar sensor in / around the sign, it reads the same speed. I've also relied on the GPS speed reading when going past speed cameras.

More often than not, a speedo will only read the correct speed within a speed range... a GPS is correct at any speed, regardless of tyre fitted, temperature, whatever. My CG125 for example reads about 83mph on the speedo, but the GPS reads 72mph (this is flat out down a local hill). At a GPS 30mph, the speedo reads 34mph at a GPS 40mph, the speedo reads 45mph.

If you don't want the expense of a GPS, then the next best thing is to fit a cycle computer. A UK biks magazine tested this up to silly speeds, and it was only a mph or two out.

 

Although a bit pricey, check this out. One of my members RAVES about it.

http://www.veypor.com/

and his Web site:

http://www.wibb-builders.co.uk/Matt/index.html

 

Heh, nice one FZR Dude...

That's the sort of thing I was thinking about.. although my idea costs about £15 or £20 from Halfords. <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s --> I used to use a cycle computer on my Bandit when I got it new. Now I use a little gearbox thingy to convert the Km/h clock into a Mph clock like this one;

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It's still about 5mph out though, which is ok.

 

must be... <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: -->