Universal Speedometer Installation - question on internal nightlight

[Sarhaider]

I want to install this speedometer. I've got some clubman bars on my 2006 ninja 250, and I was going to get a bar clamp for the speedo.

My question is about the red/white 12V connectors for the internal light. The stock gauges connect via pins, so I don't know how to go about connecting the light. Do you just remove the pins? Anyone have any ideas?

[rabies]

the front of the bike as acc connectors. plug those wires into those. .
pics of bars son.
also pics of speedomter installed when yoru done plz

[Sarhaider]

I'll put up pics sometime this weekend.

If I wanted to buy one of these universal speedometers, what sort of ratio should I be looking for?

[rabies]

ratio? should be adjustable or programable. some are. make sure the tach if its not digital get one that matches yours. goes up to 13k rpms.

[rawbert625]

you could just wire tap them.

[aristurtle]

I bought a similar speedometer recently. (The one I bought also had little LEDs for the oil/highbeam/turn/neutral lights)

Don't use the accessory wires -- they're always on, even when your bike is off and the key is out.

I cut off the stock instrument cluster's wiring harness and soldered it to the speedometer, then covered up the exposed wires with heat shrink tubing. Then I could just plug it into the plugs on the bike's wiring harness. This is the right way to do it.

Here's a picture:
http://imageshack.us/a/img571/1933/20121013143257.jpg

The wrong way to do it would be to just twist the wires together and then cover it with electrical tape. That might work for the wiring in your house but after a year on a motorcycle, that connection will be sketchy at best.

The internal light is probably an LED, so make sure you connect the wires right. Normal light bulbs (like the ones in the stock gauges) don't care, but LEDs are diodes: electricity only flows through it one way. On that speedometer, red should be +12V and black should be ground. On the stock wiring harness, black with the yellow stripe is ground, and for power you can use either the brown wire or the red with blue stripe (but not the blue with red stripe, that's the oil warning light).

Finished product:

[aristurtle]

Originally Posted by rabies

ratio? should be adjustable or programable. some are. make sure the tach if its not digital get one that matches yours. goes up to 13k rpms.

Mechanical speedometers are not adjustable.

tl;dr: you want a 2:1 ratio, and it will read about 7.6% high.

Here's why:
The stock speedometer ratio is 23:9, meaning for every 23 times the front wheel rotates, the speedometer cable rotates 9 times. You will not find a 23:9 speedometer in the aftermarket. The ratios you will find are 2240:60, which was commonly used on older Hondas, 2:1, which was used on older Yamahas and on some Harleys, and 1:1, used by most other Harleys until they started using electrical speedometers.

Now, quick math seems to imply that the 2:1 speedometer would have an error of (23/9) / (2/1) = 1.278, meaning that it would read 27.8% high. However, it's not actually that bad. You see, these speedometers are calibrated for a 19" front wheel, but the front wheel on the Ninja 250 is 16". So the error is actually ((23/9)/(2/1))*(16/19)=1.076. This is the closest you'll get with an aftermarket mechanical speedometer.

Keep in mind that the odometer will also be reading 7.6% high. In fact, that's a way to verify this: ride a route of known distance and see how far off the odometer is.
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[rabies]

^i knew that. i meant if he wired it to be digital. which is a pain. havent seen anyone do a DIY install/wiring "any brand" digital tach/speedo for pregen

[aristurtle]

If you want an electrical speedometer you will need to wire up your own speed sensor. The people on the other Ninja 250 site have instructions on how to do this with a bicycle speedometer.

Bicycle speedometers generally use their own battery and aren't backlit, though. I'm not a fan of this method.
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