I'm bringing a 1981 XL back to life. It has an aftermarket Fat Bob style tank with a dashboard mounted, HD OEM speedometer that is wrecked and I want to replace.

There are no markings on the speedometer to identify the type (1:1, 2:1, 2240:60). When I replaced the front wheel mounted speedometer cable I counted the revolutions it makes at one full turn of the OEM 19" wheel.

The cable turns more than twice for each revolution of the wheel - about 2.3:1 would be my estimate. Is that what a 2240:60 drive does?

Why does this oddball drive even exist?

Thanks!

 

I can tell you that all ironhead sportsters (whether tranny driven or front wheel driven) came from the factory with 2:1 speedometers.

On my '82, my stock speedometer says I'm going about 10% faster than I really am, and my odometer shows I've traveled about 10% farther than I really have. I had to replace my speedo once, and the stock replacement speedo was exactly the same as the original. So 2:1 isn't very accurate, IMHO.

On a 2:1 speedo, "2000 rpm of the cable equals 60 mph" on the speedo dial. On the 2240:60 speedos, it's "2240 cable rpm equals 60 mph" on the dial.

This is mostly a guess on my part, but it seems to me they're trying to improve the accuracy with the newer 2240:60 speedo, since 2240 is just a little bit more than 10% of 2000.

 

Thanks for the help! It certainly makes sense, explaining the 2:1 nomenclature brought it all together, although why it isn't termed 2000:60 is beyond me.

There aren't as many style selections in the 2240:60 style. You have to really want one I guess.

I bought one this afternoon and will be matching it to the drive that came with the bike. I'm sure it will be fine.

Thanks again!

 

I have never looked into these different speedometer ratios, so I personally have no clue as what ratio to look for, or even what the ratios mean. I would trust everything that yellowstone kelly had to say because I have known him on these forums for many years.

What I have done is, when needed, replaced with a used or aftermarket Harley Davidson model and not even given a thought to those reference numbers. And quite frankly I do not give a Tinkers D@mn if it is 10% or whatever % off

 

If my memory serves me correct, the 2240:60 was used in the early mid 90's with the reed switch to cancel the turn signals. Late 90's HD changed to the electronic speedo & turn signals. You will need a Big Twn speedo with a 2:1 ratio.

 

Texas, Reed switch...more research needed I guess. There's turn signals and they work but who knows how or if they self cancel at all.

Iron Mick, This is the same bike you advised me on a few weeks ago...New topic.

 

No IronHeads came with self cancelling turn signals - unless you mean "cancel them yourself"

 

Mick, this is an AFTERMARKET FAT BOB conversion tank with BIG TWIN speedo. Looks like you missed this little detail. LOL

 

Spurlee, take a photo of the speedo - face and back side. Let's see if it can be identified. There are still Fat Bob tank conversions out there by different manufactures. Some use 2:1, some use 2240:60.

 

I guess I should have taken a picture right away, no? I'll grab one this afternoon when I'm at the shop.