Hitchcocks Forum

Good evening, updating my 2000 bullet 500 export with a 50’s style kit, I purchased the ‘smiths’ speedo, new cable drive and new metal hub mounted speedo gearbox. However I have a huge over read. Hitchcocks state they can not take responsibility for the calibration of smiths speedo which I accepted when purchasing, I have now sent it to speedy cables to be correctly calibrated. I completed their test sheet, rotate the wheel forward one rotation and measure distance travelled, measure from centre of hub to road, then push the bike forward six rotations of the wheel and count how many times the drive cable turns. The last test is where there is some confusion, I’ve carried out the test twice, for every rotation of the wheel the speedo drive cable rotated twice. So over their specified test of six rotations of the wheel, the drive rotates twelve times. Can any one confirm this? Speedy cables seem to think their is a problem and the ratio should be one to one, every rotation of the wheel should lead to a single rotation of the drive? Any help appreciated.

They are all two to one as far as I know.

Enfield speedo drive is 2:1 as your calculation confirms

All the Indian Bullets used copies of the Smiths 2:1 speedo drive. Smiths had drives with different ratios, not relevant here unless you get a genuine smiths speedo calibrated to match, which includes tyre size.

The manufacturer of your front tyre should have some data on their web site which will either state or let you calculate the tyre circumference.

A.

Thank you for your replies, I was positive I was correct with the 2:1, speedy cables have responded saying they are unable to calibrate the speedo because of this and the only solution is to fit a gear correcting box in cable itself, which must be installed 6-8 inches from the cable end and is about the size of a large pack of cigarettes. I don't believe what they are saying so I have asked them to return the speedo and I'll find another route.

Try Speedograph Richfield Ltd.

How optimistic was the Speedo? 10percent is is pretty normal.

Speedograph Richfield and now Hitchcocks have confirmed the reproduction Indian made smiths gauge can not be recalibrated.

It’s way above 10%, if I am sat at 40mph the speedo is showing 65mph. I’ve thought about marking the correct speeds on the glass with a paint pen, but now likely try and source an accurate smiths speedo.

Unless my maths is wrong then a 65mph reading at 40mph is over 65% optimistic.

Was your speedo a ‘used’ part or a new item that you purchased? Is it a modern 'replica' of a Smiths?
Just what is it you've got? And what is it you need?

That is way above what other users have recorded. It may be worth asking our hosts if they would replace it as it looks like you have a rogue one.