Rocket Speedo Error

Toystoretom

Living Legend
Joined
Feb 25, 2006
Messages
2,449
HeHeHe... So the accepted speedo error on the Rocket (and most other Triumphs) appears to be 7% by all accounts, the TuneBoy even corrects in for this amount. Since the odometer runs directly off of the speedometer, this means that your displayed mileage is 7% too high, hurting your resale....
 

Pig9r

Living Legend
Joined
Mar 5, 2006
Messages
4,848
Location
Kansas City, MO USA
I think we need to make a tuneboy tune for Vonbonds that will not remove the 7% error but add to it. Maybe to something like 40% faster than actual speed. That way when he calculates his mileage he get over 50 mpg.
 

vonbonds

Supercharged
Joined
Mar 4, 2006
Messages
297
Location
Bel Air, MD
HAHA...good one! Since I removed the PCIII I am getting 32-33mpg with the Clearview barn door on. I can deal with that! I have almost 25K miles on my Rocket so obviously I am riding the crap out of it again :).
 

SteveRed

.060 Over
Joined
Mar 7, 2006
Messages
119
Location
Sydney, Australia
I'm not sure what to do with my PCIII... might try and put it on one of my other bikes! Will have to fit a different plug though!
 

Ogremeister

Turbocharged
Joined
Mar 9, 2006
Messages
658
Location
NW PA
Toystoretom said:
HeHeHe... So the accepted speedo error on the Rocket (and most other Triumphs) appears to be 7% by all accounts, the TuneBoy even corrects in for this amount. Since the odometer runs directly off of the speedometer, this means that your displayed mileage is 7% too high, hurting your resale....

I now have a GPS on my Rocket. I monitored speed and mileage on my last trip. The Speedo was reading between 8 & 9% faster than the GPS. However, the Odo was almost exactly the same as the GPS.
 

Pig9r

Living Legend
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Mar 5, 2006
Messages
4,848
Location
Kansas City, MO USA
That's interesting. I wonder if the speedo gets its information from one source and the odometer gets its information from another?
 

Toystoretom

Living Legend
Joined
Feb 25, 2006
Messages
2,449
They both run off of the Vehicle speed sensor, its is an AC pulse that is converted into digital info. If you look at the correction factor that TuneBoy uses you will notice that you put in a different wheel size, therefore each time the wheel rotates once a "distance" is calculated and the odometer motor turns the "numbers" to reflect the new mileage. The calculated distance traveled verses a period of time gets you the MPH. I don't know why Andy's miles didn't change but if his bike was off by about 8% his odometer should have reflected that. This info is also used by the ECM to help calculate engine load.

I wonder if Andy's GPS calculates milage more "as the crow flys" and doesn't take into account all the twists and turns actually traveled... possibly by some freaky coincidence these two cancelled each other out?? I dunno:D:D
 

wilbur-t

Top Fuel
Joined
Mar 8, 2006
Messages
1,576
Location
Carthage N.C. U.S.A.
The calculated distance traveled verses a period of time gets you the MPH. I don't know why Andy's miles didn't change but if his bike was off by about 8% his odometer should have reflected that.

I can't explain it either, but I have reset one of my odometers on the interstate and checked it against the mile markers for ten miles going about 65 mph. It seemed to be right on. I have no real way to check the speedo except comparing it with other bikes. The fact is, they all read different, even my friends matching Magnas don't agree with each other!
 

sullyjones

.060 Over
Joined
Mar 9, 2006
Messages
103
My speedo is out by about 7 % , but odo mileage seems spot on , when I compare to gps when I have it on the bike .
 

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