5mph slow??

on the way home i was running around 65mph or so i thought. when we got home my wife who followed me all the way home asked why i was driving so slow. i told her i was doing 65mph most of the time. there is a 3.50S19 for a front tire. would that size tire give that kind of reading i thought that was the stock size front tire on a 79 KZ650C.

should i go with a smaller tire to get it closer right??

A larger tire would make it closer.
Unless your speedometer reads 5 mph when you are sitting still it is off by a percentage, in this case a little less than 10%, and that's assuming the speedometer in the car you wife was driving is accurate (not usually the case).

I think all the KZ speedometers are only approximate in their readings

Back when these bikes were new, Cycle World used to publish the measured speedometer error. As I recall, the speedometers generally read somwhere around 5 to 10% fast, meaning the bike was going slower than indicated.

I found, by way of using my GPS, that at an indicated 65 MPH I was actually going 60 MPH. Showing 70 MPH results in just under 65 (speed limit for most of the local roads).

YMMV.

- Nate >>

I pass alot of those "slow down" police radar speed indicators (with the large digital speed readout) around here that I pass, many times alone so I'm sure it's me that is indicated.

I've come to the conclusion that around indicated 30mph I'm actually doing about 27. At an indicated 55 I'm doing about 50.

I say, "good". It'll keep me from getting tickets in all the towns I ride through in my commute..

Post edited by: biquetoast, at: 2006/04/03 19:03

slower speedo is always better than faster. like ya said better to be going a little slower so johnny law isnt messin with me. it sounds like i'm with everyone here so far on 5mph slow.

Yeah, I would say mine is 5-10mph off. If I'm doing 60 on the speedo it's really around 50.

Post edited by: savedrider, at: 2006/04/06 01:40

Mine seams to be stuck at 99 mph...errr...wait...I was GOING 99 mph!(or was I only doing 94?):lol:

I've always wondered about how accurate these speedos were...I'll have to try and remember to test it,this season.
Do You think that if I were to fly by a Cop at 90,that He would understand that I WANTED Him to stop Me,so I could ask HIM...exactly how fast I was going?...and NOT get a ticket?:whistle:

Sandy wrote:

Mine seams to be stuck at 99 mph...errr...wait...I was GOING 99 mph!(or was I only doing 94?):lol:

I've always wondered about how accurate these speedos were...I'll have to try and remember to test it,this season.
Do You think that if I were to fly by a Cop at 90,that He would understand that I WANTED Him to stop Me,so I could ask HIM...exactly how fast I was going?...and NOT get a ticket?:whistle:

:woohoo: lol I think the thing to do, would be to drive normal til you see a cop, then wave him over and get him to put on the lights and clock you.
Scott

77KZ650 wrote:

Sandy wrote:

Mine seams to be stuck at 99 mph...errr...wait...I was GOING 99 mph!(or was I only doing 94?):lol:

I've always wondered about how accurate these speedos were...I'll have to try and remember to test it,this season.
Do You think that if I were to fly by a Cop at 90,that He would understand that I WANTED Him to stop Me,so I could ask HIM...exactly how fast I was going?...and NOT get a ticket?:whistle:

:woohoo: lol I think the thing to do, would be to drive normal til you see a cop, then wave him over and get him to put on the lights and clock you.
Scott

LMAO...Hey Scott...I could GO places with that idea...hmmm...I could pretend that I was the lead Man in a high-speed chase(in My mind,I'd be doin 120)...LOL...I could just lead the cop all OVER the place...take Him on a nice cruise...stop for lunch...take a ferry-ride across the lake...get Him to escort Me home...then We'd sit in the garage and b.s. over a couple frosties...LOL...the whole time,I'd be TRYING to convince Him that I WAS still testing My speedo when I was doin the 120...LOL...:whistle: :lol:

timber wrote:

on the way home i was running around 65mph or so i thought. when we got home my wife who followed me all the way home asked why i was driving so slow. i told her i was doing 65mph most of the time. there is a 3.50S19 for a front tire. would that size tire give that kind of reading i thought that was the stock size front tire on a 79 KZ650C.

should i go with a smaller tire to get it closer right??

Speedo essentially counts the revs. Smaller tire will rev more at the same speed so you'll see a higher reading.

If you want to know how much of the discrepancy is caused by the count being off, you can set trip meter to 0 at a mile marker and ride until it says '1'. Measure distance to the marker to see how much the tire size is contributing to the slow reading.
h
-Duck

Post edited by: Duck, at: 2006/04/06 16:19