Topic: Testing a speedo

[my78k]

So the speedo on my bike seemed to die....it is very eratic and sometimes doesn't work at all (when I say eratic I mean it bounces wildly at speed)

Just wondering if there is a sure fire way to tell if that's the speedo itself or the drive unit? I assume the cable won't be the issue as it either works or it doesn't (snapped) or atleast that's my logic...

I removed the unit and put my drill to it and it hovered nicely at just shy of 40 km/h but with the eratic nature of it I am not sure it proves anything....also it seems to be worse at higher speeds.

Thanks,
Dennis

[Johnie]

A dry cable with no lube and ready to break will do that. I would try a new cable. They are only about $20.

[my78k]

really? I would have thought that the cable would either work or not....Could you expand on how? My intuition says it spins or it doesn' With it being attached on both ends can it be intermittent like that?

Thanks,
Dennis

P.S. I have no problem buying a new cable I just want to ensure I am not throwing good money after bad....

[BobbyR]

really? I would have thought that the cable would either work or not....Could you expand on how? My intuition says it spins or it doesn' With it being attached on both ends can it be intermittent like that?

Thanks,
Dennis

P.S. I have no problem buying a new cable I just want to ensure I am not throwing good money after bad....

Sometimes it momentarily  binds and twists like a spring and then releases, when it does that the needle will become erratic.

[Johnie]

Pay no attention to Bobbys avatar. It will distract you from the facts.
Now what was your question again?

[my78k]

You know...for a really hot blonde with killer cleavage you seem to know your stuff Bobby!

I will replace the cable and see if that solves my woes...I suspect given it's age even if it isn't the primary cause it certainly cant be helping. Plus it's the cheapest/easiest thing to tackle first.
Thanks guys,
Dennis

[ZanVooden]

My speedo on my 78K bounces as well. The cable is good. Once in awhile I just have to smear some lithium grease on the lenght of the cable, and a little extra where the cable attaches to the speedo. that eliminates the bouncing for a couple weeks.
I read somewhere on the forum that some of it can be caused by a PO using motor oil to lube the speedo which can affect the magnets in the speedo. Although dont quote me on that...

[boulder74]

Mine was dong that & I removed the cable at the drive and cleaned what I could, lubed and reattached it....it quit for a while.  Then I got the JC Whitney aftermarket speedo & tach (same cable) it's steady at any speed.  Could be your speedo going.

my $.02

[my78k]

Well my official guess is the speedo but I figure the cable could use replacing anyways so I will start there...

You mention a JC Whitney Speedo?!?!? Got a link? Can I buy just the Speedo?

My bike is a toad and I couldn't care less about looks I just need a speedo that works! I will take ANYTHING as long as the ratios match. Even the wrecker quoted me 125$ for a USED speedo!!! That's insane!!!

[Terry in Australia]

G'Day Dennis, I'm guessing it's the cable as well mate, like a previous poster said, a frayed cable will drag, momentarily bind, then snap free again, causing your needle to dance around your speedo.

My speedo cable on my gold K2 looked like new on the outside, then it started to dance around and then it stopped completely. I removed the cable and the thing looked like it had exploded inside the outer sheath. I replaced the cable (10 bucks well spent) and it now works fine again.

I don't particularly like the mini gauges I put on it, and am less impressed with the electronic speedo/tach I just bought, so I might check out Jesus C Whitney's product too!  

[Yamonda]

Hi Dennis, I have a mate who fixes my speedo's and tacko's for me, the cause of the needle bouncing around is because there is no silcon damping fluid left in the little dash pot inside your instrument, this is a very small cylinder which is fitted around the  shaft coming through to the face of the instrument.

   We are able to purchase it from the USA , and the only way to get it into the instrument is to pull it apart and inject a small amount of the silicon damping fluid into the little pot.

    He has fixed all my speedo's and tacko's , they now run very steady, the reason the fluid leaks out is because when you place the instrument upside down it slowly leaks out and you'll notice a damp patch around the shaft on the face of the instrument.

     Hope this helps you.

[Steve F]

siliconE vs. silicon
sand or polymer...I'd prefer the lubricant myself 

[OrganDonor]

If finally decide you need a speedo I have a used one with cable you can have for $50 including shipping.  It's from a 76 550F and has 10K miles on it. 

Bob

[my78k]

Well I replaced the cable and it has definitely improved. I am not convinced it totally eliminated the problem though as my only test ride was with my 8 year old girl on the back and she wasn't very comfortable at speed so I stuck to the back roads etc. I do think it is reading way fast but I suspect that may be since it came from an unknown bike (wrecker) and the ratios may not line up.

I plan on taking it to work on Fri so I should know better then (have to take the work vehicle in for service so it makes for a good excuse to ride!)

OD, I will get back to you on the weekend. I definitely have interest I just want to double check (will be bringing my GPS to see just how out of whack it is).

Thanks,
Dennis