New 8tooth driver-will they throw off the speedo? A fix

Sasquatch,

Do you know if your speedometer is off by the same percentage across its range or is just at the top end? If the reading is good at lower speeds but gains as you approach the max I suspect something at the sensor is making it pick up extra counts.

When the snow returns try checking your speedometer against a GPS at 30, 40, 50, etc. Plot what you see on the speedo against the GPS in Excel. If the two lines diverge consistently, then it's a programming function. If the two lines stay together until, say 100 kph, and then the speedometer values begin to differ significantly from the GPS values, it's likely to be a mechanical issue leading the system to over count.

You said your odometer was dead-on. This makes me think your speedometer is only off near your top end. Even if you're Speed Racer most of your seat time would still be at something less WOT where the speedo and thus the odometer is operating correctly. I don't think occasional runs at WOT wouldn't show up as a significant error on your odometer over 100 km or more.

Let me know what you find out.
 
My speedo is off at 60mph as well. At 120 on the dream meter I'm out about 14 or 15 mph. GPS is 105 mph. I've maxed out at about 122 on the dream meter. At about 60mph My GPS reads around 54 55mph.

Hard to watch both at the same time and keep a constant speed. But it seems to be off all the way through the range. Getting to be a little more off at top speed. Something I always attributed to track spin at speed. This is of course on hard pack.

My odo is very close to my GPS after a long 1000 mile trip. In a thousand miles I might be out by 20 miles give or take. The worst for out was last year when I was out by almost 100 miles of track spin in wet slushy soggy conditions. Bloody rain!
 
I have checked my speedometer against my GPS at various speeds and the "dream meter" is always about 11-12% fast regardless of speed.

The odometer however is always nuts on. Again, this tells me that Yamaha intentionally programmed the speedometer to read high to make the sled seem faster than it actually is while making sure that the odometer was still accurate.

There must be a way to alter the display programming to correct the speedometer without changing the already accurate odometer. It could be as simple as accessing a "secret" menu via the display buttons but it more likely involves a special interface cable and proprietary software.

If anybody ever figures out how to change this calibration I would be interested in learning how.
 
I'll flog this dead horse one more time because it's interesting technically.

It probably depends on the math used in the pod, but having the speed and distance functions so far off makes it seem like someone wasn’t even trying to get it right. The input for both the speedo and odometer come from the same source; the gear and sensor setup.

The simplest method mathematically is to count the impulses from the sensor and multiply this by an appropriate factor to get distance traveled. For the speed you'd count the pulses for a short duration (depending on how often you want to update the display) and divide that distance by a predetermined time interval. The more complicated method is to use the distance vs. time data and compute the derivative to get instantaneous speed. Either way, under ideal conditions, both should give you very close to the same values. It seems in your case there are separate books being kept for each function - which makes no real sense to me and strengthens the conspiracy theory.

Go with the GPS.
 
arteeex said:
I'll flog this dead horse one more time because it's interesting technically.

It probably depends on the math used in the pod, but having the speed and distance functions so far off makes it seem like someone wasn’t even trying to get it right. The input for both the speedo and odometer come from the same source; the gear and sensor setup.

I agree that it is interesting and I believe that the internal speedometer error is intentional since the odometer is accurate and they share a common input. Somebody must know how to change the speedometer calibration internally without effecting the odometer.

Most likely it requires a proprietary interface and software that not even the dealers have access to. Too bad nobody at TY works for Yamaha in the R&D or another department that is responsible for this sort of thing.
 
How about pulling the needle off and replacing it in the corrected position?
 
Mikey said:
How about pulling the needle off and replacing it in the corrected position?

The error is a % which results in the actual MPH difference being greater at higher speeds. Therefore moving the needle (if that would even be possible) would not correct the error at all speeds.
 


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