Speedometor innacuracy

Just the other night I was riding at night next to a new civic and their window was down so I could see their speedo. Mine looked like it read roughly 47 mph, i could see that his read 44 and he was pulling away from me i was like huh?

 

The odometers are fine, the speedos read very high. It's intentional and all the manufacturers do it, not just Honda. It's normal, they all do that sir! Yes you can fix the speedo with a speedohealer, but if you do, you'll screw up your odometer.

Different bikes have different mechanisms for measuring. Some bikes have a sensor on the front wheel, and running a higher or lower profile tire will change the accuracy. Some bikes have a sensor on the countershaft sprocket, and on those bikes you can change the accuracy by changing your gearing. I don't know if any VFRs have the sensor on the sprocket, or if they all have it on the front wheel. My Suzuki has the sensor on the sprocket.

 

They both get the reading from the same sensor. But if you go out on the slab and keep your speedo pointed at 60mph for 30 minutes, and see what the odometer says, you'll only have gone about 27 or 28 miles. This is because the manufacturer INTENTIONALLY makes the speedo read fast, while getting as accurate as they can with the odometer.

The speedohealer tweaks the signal coming off that sensor, to fool the instruments into thinking you're going a little slower than you are. This will drop the speedometer to the correct speed, but it will cause the odometer to read low. If you go out and do the same test, from the same start point, in 30 minutes you'll still see that your odometer says 27 or 28 miles, but you'll have gone a few miles farther down the slab than you did in the first test.

Accurate odometer or accurate speedometer? Pick one. You don't get both.

Ever installed a bicycle computer? They work the same way. There's a magnet on the wheel, it goes around and the sensor counts each time it goes by, and the computer uses this to calculate your speed and distance. It's as accurate as the number you put in for the distance traveled on one revolution of the wheel. But the motorcycle computer is sneakier. The factor it uses for the length of one wheel revolution is different for the odometer than it is for the speedometer. And you don't get to change these factors, all you can do with the speedohealer is change the count of the sensor that is monitoring how many times the wheel has gone around.

 

I noticed that on the way home, mine read 90mph while the guy I was following said he was going 75

 

If you have an analog speedometer and you're really skilled, you could create a replacement dial that has the numbers spread out a little more, so the needle would point to the same place, but the numbers behind the needle would actually be correct. Getting into the cluster to replace the dial, and getting it back together, and making it look neat, would be tricky but it's potentially doable. I'm not sure what kind of speedo the 98 has, though, maybe it's digital.

 

The SpeedoHealer does do a good job of balancing the two. For example, when I installed mine, with the factory speedometer error and a gearing change, I ended up with a 11.6% error. The calculator that comes with the SpeedoHealer allows you to then optimize the calculated error for the speedometer, the odometer or a compromise for both.

I ended up optimizing for the speedometer which then resulted in a 5.8 odometer error. I have verified this as a one-way commute to work is 28-1/4 miles. With the SpeedoHealer it now reads 30 miles. So for 100 miles, I'll read high by almost 6 miles. The cool thing about it is that you can adjust it any way you want. For myself, I want to know my exact speed at all times, so I sacrificed the odometer. Since I don't intend to ever sell the bike, it doesn't matter to me if the mileage reads high.

 

Well, i received the SpeedoHealer today, and just got it installed. I couldn't be happier and it couldn't be easier to install. The install pics on their site are all thats needed, and the calibrating is easy.

The hardest part of the whole deal is verifying your speed. I taped my GPS down to the tank and set off up the highway to verify how far it was off. At and indicated speed of 60mph i was actually doing 56.5 I was expecting it to be off more, but thats all i got. Using the caluculator on their website that computes to a -5.5% error. After entering in that info, i set off on another test ride. Perfecto-mundo !:smile: Its gonna be so nice to look down and know thats my speed and not have to think...... hmmm....... is that 5mph off, ...... or was it 8..... I dont own a vehicle that has an acurate speedo, and they are all off in a differnt way.

But, thats the cool thing about the SpeedoHealer, they make one for cars too.:biggrin: So now im ordering one for the truck.
(4:56 gears and 35" tires = speedo way off !)