Installed my SpeedoHealer today - Questions

So, I took the bike out on this gorgeous day to test the speedohealer. Some dummy had programmed the beaste with a -30% correction factor instead of the calculated -3% (I cannot tell a lie, tis moi). The device worked as it should, showing a speed of around 45 mph when my gps said I was doing 65. Got to my destination, reprogrammed it to what I thought it should be, and headed home. The SH is behaving like the directions say - it counts down, I can program it, it reveals the programming, and changes between A & B channels. It also indicates the converson symbol and toggles that feature on and off as designed.

Now, last fall I checked the odometer against the Interstate mile markers and found it to be reading about 10.3 miles for 10 mile marker posts. This calculates out to a -2.9 correction factor but I was now using a -3%. Well, today, on my return trip the odo read 9.1 miles in 10 mile posts (trip meter then, and now, same tires last fall, same tire pressure and it was 61 deg today and was probably in the 50's to 60's back then). Only difference that I can think of is that last fall's check happened at the end of a long ride and the tires themselves might have been warmer than today (only a 10 mile warmup before the measured distance). So I calculated the new correction and added -1% for a -4% total and took her out for a new spin.

This time, I get 10.1+ indicated (estimated at 10.14) over 10 mile markers. Now every one of the test runs have been on different Interstates - though the two this morning were out and back on the same I-480.

Any ideas? My goal here is to get the odometer to read exactly the Interstate mile marker distance and let the speedometer fall where it may. Last fall the speedo seemed to be reading about 7% high compared to my GPS. Btw, the speedo this morning was roughly 20mph low, then 2 mph low, and this afternoon about 2 mph low - so the speedo healer is doing something.

Next step is probably to turn the speedo healer off, and go out to the same section of interstate that I did this afternoon, run it again, calculate the total correction and check that on the way back home over the same section of interstate. Might have to wait a week or so, because I have a heavy work load this week.

A quick aside. Since the speedohealer allows a +9999.9 correction factor, this would make your bike the quickest motorcycle around with an estimated top speed of 14,241 mph. Not quite warp factor 2, but a step in the right direction.

My idea is that the mile markers are not a mile apart. I have a SH on my 1300 and have it corrected for SPEED. I have done several 100 mile comparisons with my GPS and the bike odo will read 4% short. At 100 miles on the odo I have 104 on the GPS. MULTIPLE times. Is the GPS dead on, not likely, but the best tool I have available. Doing my tests are done riding 100 miles with no stops on an interstate.

Good luck in getting it to read what you want.

Side note, done with different tires at different times of tire wear. I do not see a measurable difference in Speed or Distance error.

Kevin,
I've read that a GPS picks points along a route and calculates the straight line measurement. This injects a measurable error into its distance calculations whenever you have a curve. I have no idea how accurate they are, but 100% they are not. Surveyors use light interferometers to measure distance very accurately - usually not GPS - I think. I'm not a surveyor and might be wrong on this.

Haven't you seen a mile marker moved to the beginning or the end of a natural obstacle to an accurate placement, like a bridge, tunnel, or merge lane, exit or overpass? Do you expect the mile markers to be placed within a meter or less of where the state DOT worker thinks it should be? I think they are are reasonably accurate but they aren't really meant to be within inches, at least that is my understanding, they are reasonable estimates.

GPS does measure straight line distance but a modern one is updating 60 times a minute and most roads especially interstates have such gentle curves the error is insignificant. Pick a 10 mile section where the road is pretty much straight and the GPS will give repeatable distance/speed measurements within .01%

SMSW said:

I've read that a GPS picks points along a route and calculates the straight line measurement. This injects a measurable error into its distance calculations whenever you have a curve.

Click to expand...

This may be true if you are looking at distance to go. I am taking the distance from a point or reset data till my odo shows 100 miles driven. Like the 2 post above, it is actually taking data constantly and saving the data points. One can look at the frequency of these on my Garmin.

Mile marker posts are set as close to actual as possible, but if an obstacle prevents the spot, it is moved. Many 4 lane divided highways have marks in the left lane every quarter mile. Are they exact? That will depend on how they were set, but at least there should be no obstacle for painting the stripe on the pavement. Count 40 stripes and you will be much closer than the 10 miles shown on the mile markers. Now if you can find a city with 0.1 mile markers, those are probably more accurate as they are generally in the center divide ditch. GPS error over ten miles would be a maximum of about 60' (=/-30' on each end). The 100 miles test on a trip without many turns would be a good comparison.

Neal

Here's how I set mine up. Second page shows the arithmetic:

Here is what I believe your problem is; You installed the SpeedoHealer with the belief that it would correct the speedo and odometer. The problem is the two function are tied together on the ST. From the factory the OD us usually correct or damn close to it. On the other hand the speedo is off, usually reads high compared to what you are actually traveling. Now enter the SpeedoHealer and you set it to correct the speedo. Problem is the odometer is now going to read the same percentage less that you set the speedo for.

I think you have to make up your mind and determine if you want a more accurate speedometer or odometer but you can't have both on this bike. Now if it is the odometer that you want then remove the SpeedoHealer and you should be good to go.

I hope this clears things up for you.

I had a Speedo Healer on my ZX-6R installed at a shop here in Vegas. They put the bike on the dyno to do the calibration and it was very accurate.