Digital speedometer troubles

[Fishermanblues]

I got a new digital speedometer yesterday because my old mechanical one broke. It works fine while I'm pedaling but whenever I start the engine the speedo shuts off and resets itself. It isn't the wireless type, I've heard that the wireless ones in particular have trouble with interference from the cdi. I tried wrapping the wire in aluminum foil and grounding it to the frame to shield it from whatever interference the cdi might be causing.

Does anyone have any ideas for fixing it?

Thanks,
Andrew

[Ghost0]

Replace your spark plug wire, and while your at it the plug, with good ones. The stock plug wire has no shielding. Get a good EMI suppression plug wire. It solves the problem.

[wheelbender6]

The engine spark causes your speedo to lose its settings.
Mine goes blank upon cranking, so I quickly enter through the setup menu and it begins to work again. Give it a try.

[comfortableshoes]

try twisting the wire around the fork rather than running the wire straight down, sometimes that helps

[Fishermanblues]

I went over to autozone and bought a motorcycle wire for $5, chopped it in half and screwed it onto the cdi - that fixed it.
I will have to wait til tomorrow to see how fast I really go because I don't want to anger the neighbors too much.

Thanks for the help everybody,
Andrew

[Norman]

at radio shack they are supposed to sell a ring called a shunt,choke, shoot I can't think of the name maybe a ferrite ring? but you put the speedo wire through it one turn and its supposed to stop the RF from messing with the speedo.
Maybe someone knows the name I've, seen other posts about this problem and have had it too I cured the problem by not using the speedo on a motorized bike got it on the pedal only one, I'm lazy I hardly ever ride it.
Norman

[jasonh]

Are you referring to one of these Norman?

Snap Choke Core - RadioShack.com

You can also replace the wire for the sensor with a twisted pair (like in ethernet cable - + and - twisted around each other) and that should shield out interference too.

Yes thats the thing thanks.
Norman

[Dave31]

I've been using some wire loom with good results.

[mechanickid]

i have this problem too, i've replaced the spark wire with ngk snowmobile spark plug wire, and it didn't help. i have the 1 dollar kind from ebay.

[2door]

I'm on my third digital speedo in 700 miles. The first one didn't work at all. The 2nd one a wireless, would only go to 12MPH and the 3rd one, a WallyWorld wired cheapo worked great for about six weeks now it dies from what most of you say is ignition interference. I thought that too but wondered why it worked flawlessly for 6 weeks before having problems. I tried it this weekend, no motor, pedaled around and the thing went blank and lost its programing just like it does with the engine running. Okay, so it's not because of RF interference so what's happenin? I removed the battery and bent the little clips in to hold the batt tighter thinking maybe the batt was shaking loose from road vibration and bumps. That didn't help. It still goes blank, engine off.
I'm in the market for a good old cable drive speedo. No batteries, no electronics, no problems.
Tom