Speedo ratio what should it be.

good-hifi · Post by **good-hifi** » Sun Jan 07, 2007 10:55 pm

Please, please, please can anyone tell me what the ratio number (is that what it is called) should be on the speedo for a 1963 AJS Model 14 CSR?.

I've two speedos but they are not the same ratio. The one fitted to the bike when I bought it seems to have the end of a cable broken off in the speedo drive which means that it is not possible to get a cable far enough into it for the square end to engage properly.

I've been using the speedo off another model 14 CSR (1966) I have but it has a slightly different ration and has indicated up to 80 MPH when I reckon I've only been doing about 65.

Anyway, thing is I want to get it right and the 'borrowed' speedo has 58000 on it with the bike only having done 12000.

So if, after all that bull***t, you have forgotten what I what to know, what should the ratio figure actually be?......

CheersEdited by - good-hifi on 08 Jan 2007 07:49:59 AM

Don Madden · Post by **Don Madden** » Wed Jan 10, 2007 3:07 am

I do not have the official number to hand but the ratio printed on the speedo face is the revolutions per mile.

Calculate or measure the circumfrence of the rear tire, (rim dia. + twice the tire size x pi). Multiply by the speedo gearbox ratio, close to 1:2. Divide the mile by the figure obtained above. You should come to about 1218, depending on the actual gearbox ratio & the size tire.

Competion bikes had slightly different gearbox ratios to correct for the larger tires and/or knobby tread.

Cheers, Don.

good-hifi · Post by **good-hifi** » Sat Jan 13, 2007 11:59 am

Well having done that maths the 100% accurate figure would be 1667. Since I have a 1664 one in need of repair that will be the boy to use if I can get it fixed.

1218 would make the bike appear to be well over 100 MPH. Perhaps I'll get one of those for a track day.....