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Cable Driven Speedo Question

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Hi ,

General question here, I bought an 81 xl500s recently, the Speedo gear was missing from the front brake hub so I bought a used one of eBay and a new Speedo cable. The Speedo gear fits into the worm drive in the hub perfectly and all appears to be very smooth. Long story short, it's wildly inaccurate!  Basically the Speedo overstates the speed by 10 to 30 Kim's per hour. The faster you go the more inaccurate it gets. The needle is steady and not jerking around at all. I have verified that it's not the actual Speedo by trying a different Speedo with exactly the same results.

Any ideas? Is it possible I have the wrong Speedo gear, even though it fits the worm drive perfectly?

Of course since it's a manually driven Speedo any electronic solutions are impossible. 

Cheers

Tony

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I remember a long time ago the same thing happened to me and I eventually took apart the spedo housing and found it was disconnected there.

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Yes I wondered about doing the same but I have another, almost new speedometer and I tried that one too. Same result. So I can't work it out.

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Hmm then you maybe right about the size of the gear. Did you buy it stock?

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I bought the used part off eBay according to the OEM part number 448-044-28000.

That's the right number and eBay said that's what it was, bit did the part provider get it right?

I don't see how it could be wrong since it 'fits'. Can a different gear fit the same worm gear?

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I searched up that part number on Honda parts house and I can't seem to find it. It shows the speedo assembly but as far as the worm gear goes it seems I can't find it in the diagram. Can you send me the link to the ebay posting that you bought it from

This is the site I always use look it over perhaps I missed something

https://www.hondapartshouse.com/oemparts/l/hon/5054158ff870021c54bef264/1981-xl500s-a-parts

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Thanks I did find it on the parts house and all numbers match, so I think that the gear that you installed is indeed the correct replacement. Just curious when the bike is not moving it is at zero correct?

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Yes it's at zero perfectly. It's worth noting that it's accurate ip to about 15 klms.per hour, then the speedo starts to overstate the speed.

Thanks for your interest, it makes no sense. 

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Check your tire size.

The good news is you may have a 21" front wheel/tire mod. Super easy to get the tires you want.

The bad news is the '81 came with that ridiculous 23" wheel/tire. If you have a 21" front wheel with a speedo for the 23" wheel, you will get a higher mph indication. 

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4 minutes ago, 76xtdrvr said:

Check your tire size.

The good news is you may have a 21" front wheel/tire mod. Super easy to get the tires you want.

The bad news is the '81 came with that ridiculous 23" wheel/tire. If you have a 21" front wheel with a speedo for the 23" wheel, you will get a higher mph indication. 

Nope, no such luck everything is OEM spec, including front and rear wheels and sprockets. It's a weird one. 

The only things ng I can think of is that somehow the speedometer gear is wrong. But if it was it wouldn't fit in he work gear, right?

Thanks for your answer though.

Sorry terrible typing...if the speedometer gear was not the right one it wouldn't fit the worm gear would it?

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Possibly something to do with a mix of kph vs. mph parts?

Spotted this bevel gear on Ebay. Seller says it's for a '79 xr500 that will fit the xl500. It looks like 29t to me, but double check.  At least you can do a comparison with what you have. Can't get a pic of the worm gear.

FWIW, motorcycle speedos are often optimistic by around 7 to 10%, but not as extreme as what you're seeing.

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