SuzukiSavage.com - Speedo options

Kris01

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Speedo options
04/10/14 at 19:24:16

I've been thinking about converting my bike to chain but I need to have the speedometer read correctly. The first place I checked for a replacement speedometer (to mount on the handlebars) was Ryca. Their speedo says 60 mph=2,240 RPM. I've also found others that say this. Can someone explain this? Is this the speedo drive cable RPM or the engine RPM? Is there some kind of formula to figure what gear ratios/tire sizes are compatible with "60 mph=2240RPM"? I'm just trying to figure out my options.

BTW, digital speedos (like Trailtech) are out. Don't like 'em!

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WD Serious Thumper 2005 No Login Offline Professional "scooter trash". Posts: 5207 Rosemark TN Gender:	Re: Speedo options Reply #1 - 04/11/14 at 00:55:15 The Trail Tech on my 03 works fine. Reads a consistent 2 mph faster than the analog factory gauge. The look takes some getting used to, but, the function can't be beat. I do need a small analog gauge for the 98 full custom though, digital gauges weren't available in the era that bike is built to emulate...
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Dave

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Re: Speedo options
Reply #2 - 04/11/14 at 03:08:40

It is a shame that no one has figured out how to make an electronic speedometer in a conventional housing.....with a matching electronic tachometer in a conventional housing. You could have a vintage look with all the cool stuff that electronics offer like temperature gauge, elapsed time, trip odo, clock...yada,yada.

I have a Trail Tech Vapor and I got it so that I could have a tidy look, and the convenience of an accurate speedometer when I changed to an 18" wheel and I keep fussing around with different pulleys.

The Trail Tech Vapor requires you hooking up about a dozen wires, mounting a magnet to the front wheel and sticking the sensor on the fork leg, then mounting the unit. I have the optional dash which has indicator lights for the turn signals, neutral and high beam - they are a bit tough to see in the daylight.

Dave

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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: Speedo options Reply #3 - 04/11/14 at 05:06:47 I looked at a few overpriced Autometer gauges and they all said pretty much the same thing -- 60 mph = 2240 rpm. So how can these be compatible with ANYTHING? Every car/motorcycle/whatever has different gears/tire sizes. Am I missing something here?
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Re: Speedo options
Reply #4 - 04/11/14 at 05:55:40

Cars can use different ratio speedometer drives to account for changes in the final drive ratio. If you are looking at Motorcycle units - they are going to be built for the most common bikes, as it is just not economically affordable to make a ratio for every possible gear combination.

You can get "little" devices that can corrrect for changes in speedometer cable speeds. They are little for the use in cars but kind of bulky for motorcycle use. They also require you to make custom drive cables. or connect it right to the engine block or speedometer housing. Click on this link and you can see an adapter and cables in the upper right had corner. North Hollywood Speedometer can also recalibrate things.....for a fee.
http://www.nhspeedometer.com/

If you want an off the shelf and cheap mechanical speedo for a Savage with different gear sets and tire sizes....and you want it to be accurate.....you most likely are NOT going to find it. If you want accurate...you have to do digital!

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Kris01

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Re: Speedo options
Reply #5 - 04/11/14 at 09:29:32

Thanks Dave. I'm not wanting to spend a fortune on this so I might have to forget about an analog gauge. I don't like the digital versions but I may have to learn to live with it.

What about the Ryca analog gauge? It's one of the "60 = 2240" gauges but they use a taller tire and slightly different gearing. How can I compute what gear/tire works with a gauge like this?

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Re: Speedo options
Reply #6 - 04/11/14 at 10:17:09

Read through the Cafe' Bike Builds listed in the stickey at the top of the this section. I know some have commented about speedometer accuracy.

Also some folks have used small bicycle electronic speedometers as both accurate speedo's and a way to get a trip odometer. If you do get one make sure it has wires to the sensor, as the signal of the wireless stuff gets screwed up by the electrical activity on the Savage.

Also you can place small paint dots on your speedo face to indicate real speeds. I have a friend that changed the gearing on his dual sport, and he used his GPS to get accurate speeds to mark on his speedo face.

And lastly....I just read somewhere that GPS driven speedometers are starting to be available.

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swedishbiker Full Member Offline SuzukiSavage.com Rocks! Posts: 119 Växjö Sweden Gender:	Re: Speedo options Reply #7 - 04/11/14 at 11:02:50 http://www.wrenchmonkees.com/webshop/instruments
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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: Speedo options Reply #8 - 04/11/14 at 12:30:14 Those are some nice looking instruments! Unfortunately, anything made outside of the U.S. is going to be in km/h. I need mph.
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swedishbiker Full Member Offline SuzukiSavage.com Rocks! Posts: 119 Växjö Sweden Gender:	Re: Speedo options Reply #9 - 04/11/14 at 12:59:23 Kph or mph your choice.
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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: Speedo options Reply #10 - 04/11/14 at 13:07:04 Yep, sorry. I did notice that after re-reading that link.
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Kris01

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Re: Speedo options
Reply #11 - 04/11/14 at 13:32:55

Ok, so in my research I have found that as the speedo cable spins 2240 rpm, the speedo reads 60 mph. "2240:60" is the Japanese standard across all makes and models.

Since every bike is different as far as tires and gears go, what else is involved to make the speedo read accurately? I've been reading that a lot of bikes have a speedo gear thingy inside the front wheel hub. Ours does not have this feature. Our speedo reads off of the engine/transmission somewhere. There's got to be something else to convert gear rpms into accurate speedo cable rpms to cause the gauge to register accurately.

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runwyrlph

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Re: Speedo options
Reply #12 - 04/11/14 at 13:58:07

They would have to calibrate for each bike to make 2240 speedo rpm = 60 mph - based on the stock size rear wheel and tire e.g. for larger wheels, use a larger gear to drive the speedo cable or something like that.

I'm picturing something that runs off the front sprocket driveshaft (since it would turn proportionally to the rear wheel, regardless of engine - rpm,gear, etc then there would be some sort of gearing adjustment to make 2240 speedo = 60 mph

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Re: Speedo options
Reply #13 - 04/11/14 at 14:08:19

Kris01:

I had mentioned to you in a previous post that there is an adapter that can be used - but is is most often used on cars, trucks and busses and is not all that compact for a motorcycle. It most often screws onto the transmission and then the cable screws into it. You might be able to find one that would work on the Savage. You would have to contact a supplier and tell the me the thread sizes, and the ratio change you need so they can put the correct gears in it.

One of the reasons that dirt bikes used the front wheel to drive the speedometer is that for rallies and enduros where mileage needs to be accurate, rear wheel spin can make the mileage wrong...so they use the front wheel....and it allows sprocket changes without affecting the speedometer. You might be able to adapt a front wheel gear set up to use on the Savage - but then you need to use the same size wheel, and a 19" front wheel is not all that common.

OK....that is everything I know about speedometers.....I'm spent! Lips Sealed

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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: Speedo options Reply #14 - 04/11/14 at 19:01:01 Hmmm, I guess I'm making this more difficult than it needs to be. If I decide to regear this bike with chain, I'll probably just go the easy route with a bicycle speedometer. Yeah, I said it.... digital!
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