Topic: SpeedO is off

[SOHC Dave]

my speedo is showing 10mph fast. shows 60 I'm doing 50 according to my GPS. how can i fix that??

[bistromath]

You can't. I mean, you could open up the speedo and change/modify the return spring, but it's not exactly worth it. Most Honda speedos read high by about 10%, or 6mph at 60mph. Non-stock wheels and tires can add to that error.

[Alan F.]

hey Dave your avatar pic looks familliar, did I sell you some fork lowers from a 78 750K once over in Tilton a few summers back?

[SOHC Dave]

hey Dave your avatar pic looks familliar, did I sell you some fork lowers from a 78 750K once over in Tilton a few summers back?

yup. i need the parts for those 8in over forks. how ya been??

[SOHC Dave]

sorry,kinda hard to stay steady one handed at 100,well 90 something

[seaweb11]

Why do you care?

You have a gps.........look at that for an accurate reading.
Or.......look at your gauge and know that when it says 70mph your really only going 60

If this is the biggest issue you have with your SOHC your a member of a great "small" club

[the technological J]

every car i have been in that hasa GPS has a three or four mph difference between them usually the car reads faster but im gonna check it out with my bike because i just changed the front tire and now im curious

[SOHC Dave]

Why do you care?

caues i do

didnt know if there was different gears for the drive unit. so i guess im oin thesmall club

[SOHC Dave]

Why do you care?

caues i do

didnt know if there was different gears for the drive unit. so i guess im in the small club
 with only one issue

[Johnie]

Could always take the needle off and reset it.  Sure it may point lower when the bike is not moving, but you will have the right speed.  Maybe your bike has a peg the speedo rests against when not moving?  That would take care of it...

[SOHC Dave]

ill have to look into that. the milage will still be wrong

[Gordon]

ill have to look into that. the milage will still be wrong

If the problem is just with the speedometer, as in the spring tension is off, then the odometer is still right as long as it doesn't have its own issues.  You can check it pretty easily by riding down a stretch of highway and comparing what the odometer says to the mile markers you're passing. 

[Alan F.]

I've been doing well thanks Dave.  Motorcycle speedometers in general are notorious for being inaccurate.  Some are good at very low speeds but the error begins to creep in with each gear change and multiply as speeds rise.  I guess that's why many bikes left off the use of wheel driven speedometers.  One solution is to use a GPS to measure speed, another is to use a bicycle computer (which I'll be using when my K3 is done...but I'm keeping the stock speedo for appearances) Sigma Sport makes good ones that will read ridiculously high speeds, go with a wired unit as the wireless ones run afoul of the plug wires interference.

I wonder if a new speedometer drive at the front wheel will be any more accurate?  I wouldn't worry much about the odometer being less accurate if you move the needle a few degrees, it's probably off anyway like everyone else's.

[bistromath]

Like I said, the Honda speedos I've seen are off by a percentage, which makes sense. Mine is 10%. So if it's off by 3MPH at 30MPH, it'll be off by 6MPH at 60MPH. If you move the speedo needle, it'll only be correct at one speed.

I've gotten used to doing the mental math to know exactly how fast I'm going, so I can cruise at 82MPH indicated and be assured I won't get pulled over. =)