TOPIC:

My friend wants to keep the actuall miles on his bike correct and he bought a used speedo, his has 21k and the new speedo has 13k. Can you roll a speedo forward and if so how?

kzmarvo wrote:

My friend wants to keep the actuall miles on his bike correct and he bought a used speedo, his has 21k and the new speedo has 13k. Can you roll a speedo forward and if so how?

Buy another cheap bike. Hook it to that bike, and ride 8000 miles.

Seriously though, there have been people in the forum who have done speedo and tach reconditioning, I wonder if they could do it... Those puppies are mighty fragile though, be careful...

It would probably take too long with a dremmel or drill connected to it.... like a year...

I tried using a drill to increase the miles on an odometer one time, and a year is a pretty good guess

Go hang around some crummy used car lot. Some old guy there probably knows how to roll them BACK, just get him to show how to go forward!

I don't believe in turning odometers back, it's just wrong. That said though I don't have a problem of setting a replacement speedo to the actual mileage.

A little math might be in order. A 19 inch rim with tire is going to about 25 inches in diameter, that means the tire has a circumference of about 79 inches and will cover that amount of ground per revolution. There are 63360 inches in a mile, so divide that by the circumference and you get 802 revolution to go a mile. Take your average 3600RPM electric motor and multiply that by 60 minutes to get an hours worth of rotations and you get 216000RPH. Assuming the speedo's drive is 1:1 at he wheel then divide that by the 802 and you get about 270MPH! Divide the desired 8000 miles by 270 to get the numbers of hours needed to get the new speedo reading the same as the old.

That would be about 28 hours or a little over a day and 4 hours of constant running.

I don't think the speedo is going to like the 270MPH so I'd cut the RPM down on the motor to around 900RPM.

If you do it be sure to note the direction of rotation of the cable as the motor will have to match it so not to spin the speedo in the wrong direction. I'd also put a fan on the whole setup to keep things somewhat cool.

Post edited by: KZ_Rage, at: 2006/07/11 23:54

Sound like a pain in the pooper ta me. I'm gonna just tell him that he is either gonna deal with the change or stay with the old crunchy one. But thanks for the info ppl.

Way back in about 76 a guy I knew tried to run his Z1 speedo back before he traded it in. He hooked up a drill and left it overnight. When he came back the next day he found a burnt up drill and ruined speedo, serves him right, lol.

Post edited by: ZXDavid, at: 2006/07/12 04:29

I did it once with a drill also. You probably don't want the drill spinning at 200 mph for hours though. Not sure if it would hurt or not. If you spin a drill at 100 mph it would take 80 hours to spin 8000 miles.

Should add that I have an old Black/Decker drill from about 1980 and I ran it for days doing mine and it never burnt up or hurt a thing. I'm still using the same drill. Of course modern drills made in China probably would not hold up for 1 hr let alone 80.

easier way look here..steve
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