[billmeek]

Quite a while back I had a state trooper clock me using a radar gun since he claimed it was more accurate than his speedo. I ran acoss one of the portable radar indicators setup in the median of the road. Never one to waste the opportunity, I tried getting my speed from it too. I made 10 passes making sure I was the only vehicle it should be picking up. The state troopers radar gun and the portable radar sign both indicated my Burgman 400 speedo is off by about 6% rather than the expected 10.

 

[Pappy]

Quite a while back I had a state trooper clock me using a radar gun since he claimed it was more accurate than his speedo. I ran acoss one of the portable radar indicators setup in the median of the road. Never one to waste the opportunity, I tried getting my speed from it too. I made 10 passes making sure I was the only vehicle it should be picking up. The state troopers radar gun and the portable radar sign both indicated my Burgman 400 speedo is off by about 6% rather than the expected 10.

OK, as long as it was in the name of "research"....

 

[billmeek]

OK, as long as it was in the name of "research"....

More in the name of 'cover thy butt'

 

[ted clement]

Bill, do you think that 6% holds true at the higher speeds? The other day I stretched my 400 to an indicated 90-92mph (8000-8200 rpm): so it was about an actual 85 mph?

 

[Brian]

The state troopers radar gun and the portable radar sign both indicated my Burgman 400 speedo is off by about 6% rather than the expected 10.

Bill, I can't remember; do you still have the OEM tires, or do you have Pirelli's?

I know the digital speedos on the 650s are almost exactly 10% off (or at least mine is), but maybe with the 400s it is only 6%.

 

[billmeek]

Bill, do you think that 6% holds true at the higher speeds? The other day I stretched my 400 to an indicated 90-92mph (8000-8200 rpm): so it was about an actual 85 mph?

Haven't had a chance to clock anything higher than 65. Seemed to hold true at that speed (4 MPH off).

 

[billmeek]

Bill, I can't remember; do you still have the OEM tires, or do you have Pirelli's?

Stilll running the factory tires so far. Only have a little over 2k miles on them.

 

[Brian]

Bill, I can't remember; do you still have the OEM tires, or do you have Pirelli's?

Stilll running the factory tires so far. Only have a little over 2k miles on them.

Interesting.

So when your speedo said 65, the RADAR said 61?

Or was it RADAR said 65 and your speedo said 69?

 

[billmeek]

Speedo said 65, the RADAR said 61.

 

[Brian]

Speedo said 65, the RADAR said 61.

Very interesting.

Also, recently there has been a report that the 650 is only 3MPH fast at any speed:

... I went past one of those friendly roadside radar monitors the other day which gave me an excellent chance to check the speedo accuracy, and like my AN400, the AN650's speedo is exactly 3 MPH fast.

More research seems to be indicated.

[Read that as an excuse for me to resume my high-speed shenanigans. 8) ]

 

[billmeek]

Also, recently there has been a report that the 650 is only 3MPH fast at any speed:

More research seems to be indicated.

That is very possible. The difference at the speeds tested is only 1 mph or so. Pretty hard to be that accurate on an analog speedometer. An no....I will not go roaring by a radar gun at 95 (indicated) to check the speedo....at least not a radar owned by the government. I do have a email I sent to one of my friends to see if he's got a GPS I can use to test with.

 

[pauljo]

Bill,

First of all, I like your new avatar!

This speedo error thing is going to drive me nuts. I made the trip to Scootercade and back under the assumption that my 650 speedo was 10 percent high. This kept me pretty much with the flow of traffic - some cars were still passing me. And fortunately, I didn't get a ticket. I went by one radar trap near Kansas City doing an indicated 81 mph in a 70 mph zone, and the trooper didn't come after me (I was really pretty much right with the flow of traffic.) Maybe the safer thing to do would be to hold indicated speed to 5 mph over the speed limit - which should be in the "non-ticket" zone whether the error is 6%, 10%, or whatever. It's hard for me to ride slower than the flow of traffic though.

 

[gruntled]

Tried the GPS thing. Easy to do on a car with cruise control. Hard to do on the bike. You have to try to hold the speed exact while you watch the GPS & the road. With the car the GPS held fairly steady, with the bike it was moving all over the place.
Problem with the radar signs is that all the ones I have seen only show your speed IF you are speeding, otherwise they show the posted speed in a different color. To check your speed you have to go faster than the posted speed.

 

[Brian]

Tried the GPS thing. Easy to do on a car with cruise control. Hard to do on the bike. You have to try to hold the speed exact while you watch the GPS & the road. With the car the GPS held fairly steady, with the bike it was moving all over the place.
Problem with the radar signs is that all the ones I have seen only show your speed IF you are speeding, otherwise they show the posted speed in a different color. To check your speed you have to go faster than the posted speed.

If you have a GPS with a log, you could run at a steady speed for a while then go back to the log later to see what it truely was. Not all GPSes have logs, though.

In my area we don't have the RADAR signs like you describe. Ours have a standard speed-limit sign above and a "Your Speed Is" RADAR indicator below. It shows any speed; below, at, or above the limit.

They're portable, and they are moved around from place to place. Next time I see one I will definitely return in the wee hours when no other traffic is about to do some more testing.

 

[billmeek]

First of all, I like your new avatar!

Thanks Paul. Good to see you back from Scootercade.

This speedo error thing is going to drive me nuts.
......
Maybe the safer thing to do would be to hold indicated speed to 5 mph over the speed limit - which should be in the "non-ticket" zone whether the error is 6%, 10%, or whatever. It's hard for me to ride slower than the flow of traffic though.

I've adjustied my riding speeds just a small amount since testing with the radar sign. Even at 70 MPH, the difference between 10% and 6% is under 3 MPH. I pretty much use 3 MPH as a general adjustment for most of my riding on the open road, 4 MPH for intertstate speeds, and 1-2 MPH in town at speeds 35 and under. Found it's much easier than worrying about exact speed. I'm usually running a little over the speed limit anyway to keep up with the flow of traffic.

 

[Randy]

I have found my speed -o - is off by about 4 mph across the board -at least between 30 & 70
I find if I just keep up with traffic or do 5 mph over the posted limitI have no problem,
but then most times I am not looking to speed anyway 8)