View Full Version : Speedometer ratio

DavesXS

06-28-2008, 08:41 PM

Does any one know the speedometer ratio is 2:1 or 1:1?

I did a search and it wouldn't let me. Not enough terms or something.

Thanks

David

DavesXS

06-28-2008, 09:29 PM

I am going to replace mine with this.

http://www.debrix.com/Items/39-0578?sck=54820987&caSKU=39-0578&caTitle=60mm%204-LED%20Black%20Face%20Speedometer%20for%201973-1994%20Harley%20Big%20Twin%20XL%20Sportster

TopCatGr58

06-28-2008, 10:32 PM

Hey Dave,

I found this info on the Partsnmore.com site about their generic gauges for all jap bikes:

2240 rpm = 60mph which means that the center drive cable must spin 2240 times a minute to read 60mph.

So...some simple math ensues:

60mph=1mile per minute

1mile=5280 feet

5280 feet x 12"= 63360"

Avg. front tire 19" total diam= 26"

1 rpm = 81.64" circumference/distance travelled

63360" / 81.64=776 rpms of the wheel at 60mph

2240 / 776=2.88 ??

That's almost a 1:3 ratio..1 wheel rpm generates 3 rpms of the speedo cable.

But is this the real value?

So....you could just take the cable off your old speedo at the speedo end, put a piece of tape/chalk mark on one side of the inner square cable piece, and slowly rotate the front wheel and see how many times the cable spins around. IF it's ~3 rpms of the cable, then it's probably a 1:3 ratio!?

T.C.

DavesXS

06-28-2008, 10:47 PM

I'm not that good at math. But the end test of how many times the cable spin vs tire rotation might give me the answer. If indeed thats what the ratio represents.

I see 3 options for ratios in my searches for the right speedo. 1:1, 2:1 and 2240:60.

And I can get this same guage in any of the 3

DavesXS

06-28-2008, 11:06 PM

After hours of searching this is the best I can find.

I'll try the test tomarrow.

http://viragotechforum.com/phpBB/viewtopic.php?p=91137

81xsproject

06-29-2008, 12:20 AM

Someone posted on here once that ALL speedos read x number mph with z number rpm of the tach cable. Would be worth a search.

DavesXS

06-29-2008, 06:40 AM

Originally posted by 81xsproject

Someone posted on here once that ALL speedos read x number mph with z number rpm of the tach cable. Would be worth a search.

I have searched every thing I can. This forum, and others. The link I posted is the only definite answer I can find. The rest is all speculation. All jap bikes are supposed to be the same ratio.

Has no body on here replaced there speedo with aftermarket one? With all the speedo problems I found its hard to believe.

DavesXS

06-29-2008, 07:40 AM

Originally posted by TopCatGr58

Hey Dave,

I found this info on the Partsnmore.com site about their generic gauges for all jap bikes:

2240 rpm = 60mph which means that the center drive cable must spin 2240 times a minute to read 60mph.

So...some simple math ensues:

60mph=1mile per minute

1mile=5280 feet

5280 feet x 12"= 63360"

Avg. front tire 19" total diam= 26"

1 rpm = 81.64" circumference/distance travelled

63360" / 81.64=776 rpms of the wheel at 60mph

2240 / 776=2.88 ??

That's almost a 1:3 ratio..1 wheel rpm generates 3 rpms of the speedo cable.

But is this the real value?

So....you could just take the cable off your old speedo at the speedo end, put a piece of tape/chalk mark on one side of the inner square cable piece, and slowly rotate the front wheel and see how many times the cable spins around. IF it's ~3 rpms of the cable, then it's probably a 1:3 ratio!?

T.C.

I did the test. Your right on. 7 wheel turns=20 cable turns. So its barely off of 3:1 ratio. If thats what the ratio is based on.

As per your post above, does this mean the ratio is 2240:60?

I guess if no body here knows for sure 100% then I'll ask Yamaha tomarrow.

DavesXS

06-29-2008, 09:07 AM

Just paced my bike with my dads car. My speedo is almost exactly 10mph off.

Theres a lot of cool speedo's out there, soon as I can be 100% on the ratio.

planedick

06-29-2008, 10:49 AM

We have radar speed signs around here. ie: Speed limit is 40 mph, I approach the sign at indicated 50 mph and the sign says "Your speed 45 mph, slow down" so I know mine is 5 mph fast and every XS11 I've seen so far is also 5 mph fast too. I have also checked the mileage on highway trips using the mile post signs and find in 5 miles the XS11 indicates 5.2 miles.

TopCatGr58

06-29-2008, 11:12 AM

Hey Dave,

Some other searches I've done recently regarding speedo drive units...for Harleys, and they list 3 distinct drive ratios,

1:1

2:1

AND 2240:60 which is the Jap bike ratio, which we have speculated/calculated to a 2:88:1 ratio!?

So....I'm speculating that the gauge with 2:1 ration will NOT be accurate! :( Hopefully you can exchange it with one designed for the 2240:60 ratio, or get a refund and buy a different one!?

T.C.

DavesXS

06-29-2008, 11:49 AM

Originally posted by TopCatGr58

Hey Dave,

Some other searches I've done recently regarding speedo drive units...for Harleys, and they list 3 distinct drive ratios,

1:1

2:1

AND 2240:60 which is the Jap bike ratio, which we have speculated/calculated to a 2:88:1 ratio!?

So....I'm speculating that the gauge with 2:1 ration will NOT be accurate! :( Hopefully you can exchange it with one designed for the 2240:60 ratio, or get a refund and buy a different one!?

T.C.

I havn't ordered anything yet. I have a 2240:60 one loadded in the shopping cart along with some cool mirrors. I am so close to hitting the confirm order tab.

I just want to be sure. Always try to look before I leap. I am still considering checking with yamaha in the morning befor clicking the order.

Whats gonna be funny is if nobody at yamaha can tell me either.:p

Thanks for the time you guys have spent helping especially you TC:D

I'll post results and definitive answers to this when I get the speedo.

Still waiting for my tach too

dbeardslee

06-29-2008, 11:59 AM

Dave - did a little checking, and it appears that the 1:1 and 1:2 ratios are for transmission driven speedometers. The only other ratio I could find is 2240:60 for the front wheel driven speedos. This being the case I'm thinkin' it's the front wheel speedo drive and its gearing that makes the adjustment for different wheel sizes. If the jap bike speedo's are all 2240:60 as the literature suggests then you already have the right speedo drive. If you're off on more than one speedo, I'd take a close look at that drive and make sure the hole isn't rounded out.

DavesXS

06-29-2008, 12:49 PM

I finally found definitive answer.

Control Japan 2 1/4" Dia. Chrome/Black MPH

All Japanese Motorcycles are equipped with mechanical speedometers of 2240 RPM= 60mph! This will work on all Japanese bikes with cable driven Speedo! Universal on all Japanese Bikes - Honda, Kawasaki, Yamaha, Suzuki. Great for Cafe Racer or Retro Projects. 2.25" Dia.

Category: Control

At this site: http://www.oldbikebarn.com/Motorcycle_Parts/Speedometer/Mini-Speedo

Shopping cart, click, confirm, and speedo/mirrors on the way:D

http://www.debrix.com/Items/39-0859?sck=21568647&caSKU=39-0859&caTitle=2240%3a60%20Ratio%2060mm%20Digital%20Speed ometer%20for%20Harley%20Big%20Twin%20Sportster

http://www.debrix.com/Items/34-0722?sck=21568647&caSKU=34-0722&caTitle=Chrome%20BILLET%20Smooth%20Ace%20Style%20M irror%20for%20Harley%20%26%20Custom

JACKHAMMER01

06-29-2008, 05:06 PM

Dave, at $70 from Old bike barn you don't even get the indicator lights! So, in an effort to be nice and help someone find the needed part, go to;

http://www.mikesxs.net/mikesxs-accessories.php?category_id=8.5 I beleive you'll find what you need, at a better price, and yes they work perfectly for the XS1100

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