[smitchell22]

Hello! I just bought my first bike, a 1979 cm400t, and the only major problem with the bike is the speedo has been busted and does not work, the cable does still spin the gauge just spins around. I'm wanting to replace the speedo but I really don't know what I should get, I'm looking for any advice I can get, the speedo does not have to be original (just not expensive since it's my first bike) I just want something that will work. Thanks in advance for any and all help!

 

[tepetit53]

What do you mean 'the gauge just spins around'?
You'll need a Factory Service Manual. PM sent.

 

[smitchell22]

When I got the bike the previous owner removed the throttle cable from the speedometer, after I got the bike i reattached the cable to the speedometer after doing so I went for a drive and even at slow speed it was showing me going 80mph as I sped up the needle just went around and around.

 

[dtsmjr8dan]

Welcome to the forum. Great to see another 400 series here. Got any pics of it to share?
Here's some good reading....http://www.hondatwins.net/forums/74...n/18504-basic-checklist-new-you-old-bike.html
You'll also need a manual. PM sent.
AFAIK, any speedo from 79 to 81 CM400 and 82 to at least 85 450 should be fine.

 

[tepetit53]

Sounds like your speedo is sticking. Mine used to fluctuate between 20 and 60. Lubed the cable with liquid graphite (lock oil) makinf sure that the drive going into the speedo was well lubed. Wicked up into the speedo and now it works very well. (took 3 times before it got rock solid, though)

Either that, or your flux capacitor is overcharged

 

[dtsmjr8dan]

Dirt/grease gets between the magnets and the disc attached to the needle shaft and instead of magnetism driving the disc, there is a physical connection between the two. (Most common.)

They are old units and could also be worn bearing surface causing misalignment of the shaft with the magnets to contact the disc.

 

[smitchell22]

Thank you for all the helpful replies but I did forget to mention in the original post that the speedo looks to have had a screw come out and that's what caused it to quit, the trip and odometer both have fallen back into the speedometer. I'm not sure if this is something I can fix myself or if it's better to just buy a different speedo.

 

[longdistancerider]

The speedo can be opened up by slowly and carefully bending open the band that holds the whole unit together. There's a couple of you tube video's and some other stuff if you search Google. I haven't done it so no other real info to offer