Speedo problem / issue. need help - Honda RC51 Forum : RC51 Motorcycle Forums
 
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post #1 of 6 (permalink) Old 08-06-2013, 01:56 PM Thread Starter
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Speedo problem / issue. need help

as I went for a ride at lunch today I noticed that my speedo was going haywire. Once I got past third gear and above 4,000 RPM, the speedometer would start sowing some wildly varying numbers. For example, in 6th gear it would read that I was doing 90 at 5,000, but then it would suddenly go to 76mph. then to 86 and so on. At one point when I was at 4500 rpm, it dropped to 0mph, then 23, the 36, then 3, then 76, then 85 etc...

I'm trying to figure out how the speedometer works, and where the measurements are taken or where the sensor is. Also, I have a few tight links in the chain and will be replacing it in a bit. not sure if that would cause any of the issues. -I could see the bouncing of 4-6mph but for the speedo to drop to 0, its nearly imposssible.

BTW, i have stock gearing as far as I can tell, no speedo healer and no power commander.
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post #2 of 6 (permalink) Old 08-06-2013, 03:47 PM
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Sounds like a faulty speed sensor or connection. The sensor is at the right rear of the motor near a ground. Find it and follow the wiring
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post #3 of 6 (permalink) Old 08-06-2013, 05:26 PM Thread Starter
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Thanks. That gives me some place to look at least. I also noticed it started doing it in every gear, and almost every RPM. The temp gauge works fine and the RPM bar works fine. I have to assume it is the sensor or wiring. Supposed to rain for the next three days so I hope I can get things sorted by next Monday.
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post #4 of 6 (permalink) Old 08-18-2013, 10:24 AM Thread Starter
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Well I replaced the speed sensor last night and went for a ride today. Same exact issue. There isn't a lot of wiring either, as the pigtail connects to the main harness which leads right into the engine control computer, after maybe 9" of wire.

This is so frustrating because I know it cannot be more than a handful of things, among them were the speed sensor, the computer, or the dash panel. Since the bike runs perfect in every other way, I have to imagine the computer is good. Today on my ride I mashed the throttle and the bike took off but the speedo didn't. Just read 0. Hit the highway and got to at least 90 or 100 and same thing... it bounces around then hits 0.

I had no issues until I adjusted my chain. I had found it was really loose and had a pile of tight links. (bought the bike used just over a month back) The only thing I can possibly think of is that the tight links are causing an issue with maybe the clutch or the output shaft as you can feel the chain "catch and release" as it goes around the front sprocket. I think I may just buy a cheap chain to test my theory as this could get pricey in a hurry if that isn't the problem. I have no idea what computers go for, but I can't imagine that they are cheap, even used.
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post #5 of 6 (permalink) Old 08-18-2013, 10:28 AM
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Man, I'd be getting that chain changed out. I sure as hell wouldn't be doing no 90 - 100mph with all those kinks you know you have.

John, 2000 RC51 #000100

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post #6 of 6 (permalink) Old 08-18-2013, 10:31 AM Thread Starter
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Yeah it kinds a pissed me off because the back sprocket looks new with no wear. The chain is a DID and is either stretched a fair amount or it has the wrong amount of links on it. Either way it need to be replaced. Will probably order one up on Monday as long as I can figure out what size it is. This is so frustrating because I love love love the bike in every other respect.
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