If your speedometer isn't working, there are three culprits. Not sure if this applies to the SOHC's.
1. The unit (the part that displays the speed) is broken - I don't think that this is serviceable - ebay has lots
2. The cable is bent/broken/kinked/binding - check the path for binding, and either pull the sleeve off for inspection or disconnect from the unit and lay as flat as possible on the ground and spin the wheel. If it flops around a significant amount it's probably kinked and you need to replace it. You should also make sure that the cable is well lubed.
3. The part attached to the front tire needs servicing. Detailed instructions below.
First you'll need to put the bike on the centre stand, slightly loosen the nuts that attach the front tire, and lift the front tire. If you can't jack it up because of your exhaust (I can't), and easy way to lift it is to use a ratchet strap connected to a sturdy rafter.
Finish removing the nuts and take the front tire off. Unscrew the phillips head screw and disconnect the speedo cable. Remove the axle. I needed a 16mm and a 22mm wrench (or I would have if this wasn't so loose that the speedometer gear was unseated, which was causing my speedometer to not work at all).
Pull out the axle, nut and speedo.
Now clean the old grease out portion attached to the wheel
And the speedo
I also used this opportunity to give the speedo a good cleaning. The outside of it was caked in old grease.
Repack new grease in the speedo
And the wheel
Reassemble the wheel.
Ensure that the speedometer seats correctly. If it does, the flat piece you can see in the end should spin when you move it. See the video below for a demonstration.
Put the wheel back on the bike and you're good to go.
My speedo is a little crazy, and 9 MPH over, at 55 MPH (actual speed is 46...). I took the cable apart, cleaned it of all oil/grease, and then I applied wheel bearing grease along its length, before sliding it back into the outer cable housing. It improved the performance (reduced the jumping around), but not the accuracy. I may need to go this route. Heaven knows what 33-year-old grease (with 22,000 miles on it) will look like.
Thanks for sharing. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
After doing this, my speedometer has been rock steady - almost no jumping. My tach still jumps a lot though and the steady speedo makes it appear even more erratic in comparison.
I don't think it fixed the accuracy, nor did I expect it to. Its a gear, a cleaning shouldn't impact accuracy much.
It was a surprisingly simple job to do. The part that took the longest was cleaning the gearbox, but that is just because I wanted it to look decent.
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I am a little afraid to disassemble my front tire... I am afraid of what the grease will look like, as it is likely the original, from the factory, circa 1979.
My speedo is a little crazy, and 9 MPH over, at 55 MPH (actual speed is 46...). I took the cable apart, cleaned it of all oil/grease, and then I applied wheel bearing grease along its length, before sliding it back into the outer cable housing. It improved the performance (reduced the jumping around), but not the accuracy. I may need to go this route. Heaven knows what 33-year-old grease (with 22,000 miles on it) will look like. Thanks for sharing. Cheers!
1979 CB750K
1993 Kawasaki Voyager XII
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Is it necessary to remove the front axle? It almost seems as though you could remove the speedo gear assembly without pulling the wheel. Also, did you clean and re-grease the axle when you reassembled the front end? I have not looked at the FSM on this topic, yet, but it seems as though it would be a good idea to re-grease the bearing, as long as you have it all apart. Just curious. After hearing that this mostly eliminated the bounce in your speedo needle, it seems as though I really do need to perform this maintenance. Besides, it sounds like it will be fun to do.
You have me wondering if a similar cleaning/re-greasing could cure the tachometer of its jitters, but this would be much more complicated to achieve. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
The axle passes thru the speedo drive,so the wheel would have to come off. I have been curious how the tach cables are setup on the DOHC's.On my SOHC the tach cable stay full of oil that comes out of the valvecover. I have a new tach seal in place and it doesnt leak whatsoever,but if you pull the cable it'll drain quite a bit of oil.
Yep, I did regrease the front axle while I did this. It is a great time to do it since it was off already.
Regarding the tach, I didn't think lubrication would be a problem because I thought it would just get oil from the engine as opposed to needing grease. Maybe I'm wrong?
Sent from my BlackBerry device on the Rogers Wireless Network
Is it necessary to remove the front axle? It almost seems as though you could remove the speedo gear assembly without pulling the wheel. Also, did you clean and re-grease the axle when you reassembled the front end? I have not looked at the FSM on this topic, yet, but it seems as though it would be a good idea to re-grease the bearing, as long as you have it all apart. Just curious. After hearing that this mostly eliminated the bounce in your speedo needle, it seems as though I really do need to perform this maintenance. Besides, it sounds like it will be fun to do.
You have me wondering if a similar cleaning/re-greasing could cure the tachometer of its jitters, but this would be much more complicated to achieve. Cheers!
1979 CB750K
1993 Kawasaki Voyager XII
If you reply to this email, your message will be added to the discussion below:
There's probably a little bit of oil in the tach cable, since the "business end" is inside the valve cover. The seal is to keep oil from getting on the headers/engine/ground/back-tire.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
Well, considering the tachometer cable is not sealed (as far as I can tell), and the oil pressure maxes out at 72 PSI (on DOHC's), I am guessing the cable end plugs into a spinning gear, rather than penetrating the valve cover. That 72 PSI can really throw a jet-stream of oil! When I put my oil cooler on, initially, I used worm-gear hose clamps (later replaced with T-bolt hose clamps): there was a thin jet-stream of oil that shot straight down, past the hose clamps, onto the ground, creating a rapidly growing puddle... I believe the same would happen were the cable to plug into the header cover, as the cable would then be subjected to the oil pressurized within the engine. One way to find out, is to pull the cable, start the engine, and see if I get a geyser.
My thought in bringing it up is that my tachometer needle really jumps around. Perhaps if I clean it out, then re-grease it, it might settle down a bit? Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
The cable does go in to where oil is in the valve cover,but not in the galley itself,where pump pressure is present. A gear is mounted on the valve cover that runs off another gear that is made on to the cam. The oil present is run-off or sling-off oil from inside the cover. Not pressurized,but will leak like crazy if the tach seal goes,nothing like your jet stream hose ordeal,of courseSo the DOHC's are cable driven too,that answers one of my many questions.
Locked
So the DOHC's are cable driven too,that answers one of my many questions.
