I'm going 50 MPH!!!!

Discussion in 'General Questions' started by emdude, Mar 12, 2009.

  1. emdude

    emdude Member

    ....not really.

    I just installed one of those cheapo $15 speedo's I'm sure many others have also used. I assume the following:

    Since the speedo gear drive at the wheel takes up space one side only we simply "shift" the front axle in the wheel hub until after installation there is roughly equal "thread meat" on either side of the axle after the wheel is installed in the now slightly spread front fork and live with the small amount of wheel offset.

    Yes, I do ok at run on sentences.

    I have no clue as to it's accuracy but if nothing else it will provide some form of comparative value as things are changed on the bike or engine. So long as readings remain reasonably constant.

    The problem I have is that at speeds above about 35 mph, and I don't mean to sound as though this is accurate, the speedo goes completely nuts. The needle will jump around, show a slower speed or sometimes peg the speedo!!!

    Initially I thought this may be due to vibration but after a few more runs I think the gears in the drive or something in the speedo is slipping and causing some pretty "off" readings.

    Do we know if these things break in in any way and settled readings become the norm, at all speeds, or do I need to open either side up for fixing?

  2. Zev0

    Zev0 Member

    That is the norm. They are made of plastic and COMPLETELY unreliable. I got a whizzer speedo and it works like a charm. Have over 1300 miles on it now and its as smooth as steady as the day I installed it.
  3. biken stins

    biken stins Member

    The problem I have is that at speeds above about 35 mph, and I don't mean to sound as though this is accurate, the speedo goes completely nuts. The needle will jump around, show a slower speed or sometimes peg the speedo!!!


    Maybe it is the bikes way of telling you something.
    Keep the rubber on the road.
  4. smitty

    smitty Guest

    I had an experience with a Whizzer speedometer, that would read fine, then it would start to buzz and the needle would fluctuate wildly. It turns out that it needed lubrication. I pulled the cable off the back of the gauge and put a few drops of TRIFLOW between the housing and the square holed cable fitting. After that the needle was quite steady, though I'm not sure how accurate it was. I broke the speedometer when my front brake shoe broke and locked the wheel and I went over the handlebar. (ouch.)
  5. spad4me

    spad4me Member

    It sounds like the cable is binding due to lack of lubrication.
    Try removing the inner cable grease the cable thoroughly and reinstall it.
    But hey the part could be so cheapy made . It will never workright
  6. macarollo

    macarollo Guest

    You got me excited when you said you went 50mph... thought we could initiate another into the club.

    It sounds like you have a mechanical speedo. I bought a cheapo speedomoter at walmart... $9.99. It is digital, very easy to install and pretty accurate. I went on a ride with it and a portable GPS and it was pretty much right on.

    It is made by Bell.
  7. HoughMade

    HoughMade Guest

    You can improve the longevity of the analog speedo by taking the spring out of the cable and greasing the whole thing. Also, avoid sharp bends.
  8. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor


    I used a new Whizzer speedometer on my new EZ Motorbike proto-type, and at approx. 475 miles the needle developed the "shakes". I continued to use it up to 500 miles, and then replaced it with another new one. The new speedometer has logged 573 miles, making the total 1073 miles. Of course I checked and re-lubed the original cable, but didn't solve the problem with the first speedometer. I now have a box with 3 defective Whizzer speedometers, they all work, but shake around 35 MPH.

    Have fun,
  9. emdude

    emdude Member

    Well, in case anyone might care, I did managed to "improve" my speedometers performance...if you can call it that.

    I took the whole thing out and investigated it a bit. I attached the "sending" end into a drill and ran it. I found out the the wild response at higher readings was caused by flutter...so to speak of the inner drive cable. It was WELL lubed.
    What occurs is that it has a tendency to wind up a bit and then quickly unwind. This causes the needle freak out.

    So I "dampened" the whole drive cable assembly, I had little to loose anyway, by covering the entire inner drive cable with heavy wheel bearing grease. This of course puts substantial drag on the whole thing but no longer does the wind up dance. I wonder how long the drive gears in the hub will hold up?

    The speedo, although I'm sure not remotely accurate in real world readings, does now work with some consistency. And the needle no longer goes wild at higher readings. So long as it will give consistent readings even if off by many mph that's all I can really ask for from a cheapo so that I know if my bike is getting faster or slower on any given known road.

    Also, this is NOT a conventional magnet drive speedometer. It's based on some type of "drag" against the return force of the needles spring. You kind of get the hint when you look at the back of the speedometer cable receptical and see that clear really sticky grease all over the place. This is the same stuff they use in electronic rotary controls to create the correct amount of drag to make it feel right.

    If you slowly push the bike up to say a 5 mph reading and then stop the needle will stay at 5 mph...hint.
  10. Irish John

    Irish John Guest

    I drip "White Lightening" bike oil down my cables - it's a white coloured silica based lubricant that seems to keep the cables free of water and smooth to use. A graphite based oil might be better or maybe something with Teflon in it. The good thing about White Lightening is it really grips and sticks after a few minutes of flowing. It's meant for chains really.
  11. ZnsaneRyder

    ZnsaneRyder Member

    I was hoping you were going 50 for real..............hehehe

    Maybe one day, someone here will hit 55mph.
  12. macarollo

    macarollo Guest

    I think someone has... 56mph I think... maybe it was 54.

    It was a small engine too... maybe 50cc high performance engine.

    I definately don't think anyone has hit 60mph.
  13. ZnsaneRyder

    ZnsaneRyder Member

    Kawasaki999 has hit 57mph with his, 43cc sooped-up go-ped engine.

    I've been to 52, so I'm planning on 55mph goal for my next build, but I'll sure try to hit 60 with enough RPM hehehe! I hope the old farts get scared already.
  14. macarollo

    macarollo Guest

    How do you plan to hit 55mph?

    Do you think the 196cc HF engine is limited to around 50mph by lack of HP OR is it all gearing? If you geared it really high would it have enough power to push a bike to 60mph?

    When I got to 50mph the bike just wouldn't go any faster... I think it was around 5200rpm, but I think the engine can rev faster. Maybe with a performance muffler that flows better it could reach higher RPM's.

    I think if you gear that engine much higher than 3:1 you start to lose usable power.... unless you were to use a CVT... maybe that is the ticket to high speeds.... use a smaller sprocket and also use a CVT.
  15. ZnsaneRyder

    ZnsaneRyder Member

    I'm going to use a 13-inch tire with a 3.2:1 ratio. (10T/32T) Calculates 55mph @ 4550 RPM.

    I'm sure they are HP limited some, but most stock engines can't rev much past 5200 because of valve-float. The stock valve springs are weak, but you can upgrade to 18lb valve springs to get 6000RPM from them. The go-kart guys are getting 9-13HP and over 8000 RPM out of them with some mods........just imagine 10+HP on a bicycle!
    Last edited: Mar 14, 2009