How far off is your old Speedo ?

[Mekanix]

I checked mine against a Gps and it looks like I'm reading 10km slow all the time.

Has anyone ever found a way to adjust the reading ?

[refeicul]

im just spit balling here but there are a few factors that i can see. 1 is tire size oem vs. 110/90 or 100/90's. 2nd are your cables properly lubed? 3rd your speedo gear under or over greased? the bearings in such? on my GS is probably one of the most accurate but on my 93 kawa its about 10mph under and my 86 honda is 5mph under. and these are just averages some times i have seen that at lower in town speeds it maybe off by such and such, and at highway speeds it would be pretty accurate. sometimes on other bikes the opposite is true.

i really see only 3 options 1st is are you sure your gps is an accurate speedo check it at a "your speed is" sign or if you are friends with an officer of the law if he could clock you. 2nd is cleaning, refitting with proper/new hardware on the bike. and 3rd knowing you off maybe good enough. the limit is 35 and your gauge reads 10 under make your speedo says 45

[posplayr]

cant help, but after my GSXR conversion I was happy to find out my speedo was actually prety accurate. (1988 GSXR wheel and speedo drive with a 83 GS1100ED 140 mph speedo) I'm guessing it is not more than 1-2 mph off at 70 mph.

I used GPS and the occasional radars that are located on teh freeways. My more accurate data came from a data logger (with rear wheel pickup)but that is probably to much to suggest.

[Nessism]

In my experience most of the time the GS speedos read high, not low. Moving to a larger front tire, which most of us have done, improves the accuracy, not hurt it. And lubing the cable and such doesn't do squat for speedo accuracy.

These speedos work off a magnetic disc pulling a metal dome shaped piece. There is no direct drive for the speedo, but the odometer is. The magnetic field works against the spring on the speedo needle, and against the needle damping mechanism. I think it's this damping mechanism that gets old, thus the speedo needle often start to wobble like crazy, and get even more inaccurate. I've yet to find a reasonable way to renew these units. Even if you crack open the gauge there is no access to refresh the damping mechanism. If anyone comes up with a good fix it would be nice to know.

Edit: messed up on the high vs. low.

[north49]

...you can take / send your speedo to a calibration shop. They compare your speedo to a calibrated standard speedo and increase / decrease the magnetic strength of the drive disk to calibrate your speedo. It takes about 10 minutes.

[Nessism]

...you can take / send your speedo to a calibration shop. They compare your speedo to a calibrated standard speedo and increase / decrease the magnetic strength of the drive disk to calibrate your speedo. It takes about 10 minutes.

Please prove info of a place that will do this for a GS speedo.

[sparkey]

Mine is real close maybe a mile an hour slow according to my wifes car

[Steve]

I checked mine against a Gps and it looks like I'm reading 10km slow all the time.

My wife's bike is off in one direction, mine is off in the other. Overall, they cancel each other out.

At an indicated 70 mph, the GPS shows her speed as 68.7
At an indicated 70 mph, the (same) GPS shows my speed as 71.4.

How to adjust? The easiest way I know of is to change the size of the tire. We have gone from the standard 90/90-10 on the front to a 100/90-19, but of different manufacturers, so the actual diameter might be just a little different.

Usually, the speedos will read a bit HIGH. A couple of reasons for that. One, the Federal government allows a bit of tolerance in the reading, but it should not be less than actual speed, so the manufacturers aim for the middle of the tolerance. Some speedos will read low, others will read high, some might actually be accurate.
Since they tend to read high, putting on a tire that is one size larger will slow the wheel down and get the speedo closer to accurate.

The second reason (in my opinion) is bragging rights. Somebody will come back from a ride on his HondaKawaYamaZuki saying "I just hit 157 mph out there"and others might rush out to get the same bike. Doesn't matter that he was only going 145, he saw 157.

... are you sure your gps is an accurate speedo?

A GPS is about as accurate as you are going to get without getting out the labratory equipment. Due to calculation differences (the way the GPS determines your location), the speed will bounce a bit if you have "tenths" showing, but overall, you will see it centering on a single number. For example, if I am going 70 mph, my GPS readings will vary from about 69.5 to 70.5, even with the cruise control ON, holding speed VERY steady. That is certainly close enough to check your bike's speedo accuracy.

.

[1_v8_merc]

Mines pretty dead on, surprisingly.
Used GPS, and side by side with my other cars.

Also rode with some newer bikes, and was perfect.

My tach on the other hand......yikes.

[old_chopper]

Mine is WAY off, like completely off the bike. I just couldn't put a speedo-meter on a chopper.

[Mekanix]

Well i fixed it, Somewhat.

I already had it cut open before, so this time i took it apart again and bent the tab that the return spring was attached to,

Now its within 4kmh at 50kmh, but I didn't have a chance to test it throughout the full speed range that I use.

It might be off more on the high end.

Will try again tomorrow.


This all started when a friend said I was too fast for them, but for some reason it never feels fast and I keep up with traffic while they are usually holding up traffic by 3-4 car lenghts :P

[Mekanix]

This is bad.

at 40 0n the gps I'm actually doing 45

50-59

60-73
70-82
90-100

((((95-110))) this is my highway driving speed

100-124
((110-133)) this is what i was actually doing
120-139
139-147

going to tweek it a bit more.