Tachometer

Discussion in 'Motorized Bicycle General Discussion' started by MarkTur, Jun 7, 2008.

  1. Mike Hunt

    Mike Hunt New Member

    Joined:
    Jun 9, 2009
    Messages:
    184
    Likes Received:
    0
  2. Coval_PL

    Coval_PL New Member

    Joined:
    Jul 28, 2009
    Messages:
    57
    Likes Received:
    0
    I have an idea, that i want to try. I want to use standard cyclo-computer and place his sensor near magneto. The sensor is a magnetic sensitive element, which has 2 little steel "leaves" that contact when the magnet mounted on the bicycle's weel goes by. I'm curious if it's possible to set computer so it will show approximates value of engine turns. I have to calculate how to set "wheel size" to get good results.
    I don't know if this device can record impulse so fast as magneto turns. If it could handle it it will be cheapest way to measure RPM's :)

    zpt
     
  3. Dan

    Dan Staff
    Staff Member

    Joined:
    May 25, 2008
    Messages:
    12,641
    Likes Received:
    62
    Great idea Coval! Keep posting. That is great out of the box thinking and I am really curious!
     
  4. Coval_PL

    Coval_PL New Member

    Joined:
    Jul 28, 2009
    Messages:
    57
    Likes Received:
    0
    I made a quick calculation and if 1000RMP would be tepresented by 10km/h, the "wheel size" in cyclocomputer must be set to around 8cm. (wheel size setting resolution is 1cm). I hope this little computer can be set to this value and hold this frequency.

    My calculation:
    10km/h = 2,78m/s
    1000 Rounds/Min=16,66 Rounds/Sec
    so: 2,78ms / 16,66 R/S = 0,1669 = 16,69cm

    Magneto has 2 poles so it makes 2 tacts per round, that mean 16,69cm mus be divided by 2. It gives result around 8cm (exacly 8,35cm).

    The same calculation has to be done for US miles/h.
    Am I right?
     
    #44 Coval_PL, Aug 11, 2009
    Last edited: Aug 11, 2009
  5. Coval_PL

    Coval_PL New Member

    Joined:
    Jul 28, 2009
    Messages:
    57
    Likes Received:
    0
  6. BarelyAWake

    BarelyAWake New Member

    Joined:
    Jul 21, 2009
    Messages:
    7,209
    Likes Received:
    5
    Tiny-Tach is an awesome product, I've had them before. Small, simple, perfect for this application...

    why the heck didn't I think of that? /facepalm lol Thanks guys!

    Tiny-Tach: Gasoline Tachometers
     
    #46 BarelyAWake, Aug 11, 2009
    Last edited: Aug 11, 2009
  7. Coval_PL

    Coval_PL New Member

    Joined:
    Jul 28, 2009
    Messages:
    57
    Likes Received:
    0
    I would really like to try this device, but it's not available in Poland :( I need to find another solutions .
     
    #47 Coval_PL, Aug 11, 2009
    Last edited: Aug 11, 2009
  8. Coval_PL

    Coval_PL New Member

    Joined:
    Jul 28, 2009
    Messages:
    57
    Likes Received:
    0
    I have bought two sets of this cyclocomputer linked in my previous post. It looks great. I would be happy MBiker if this could be works as RPM meter. I'll have both of them on my bike: one for speed and one for RPMs :D
    Unfortunatelly I have to wait allmost 2 weeks becouse i just started my vacation :(
     
  9. restapukin

    restapukin New Member

    Joined:
    Jul 22, 2009
    Messages:
    112
    Likes Received:
    0
    Got a harmonica? or guitar pitch-pipes?

    when an engine is running in the midrange @ 3,300 it will be in-tune with the A note on a musical instrument.....

    mmm... but 6,600 revs is also an 'A' ...as is 1,650rpm and 825rpm...

    once upon a time you could buy a "tyne tachometer", they looked like a metal dreadlock comb.... you mounted 'em to the chassis somewhere and watched for which comb prong or tyne was vibrating in tune with the motor....
     
  10. Norman

    Norman LORD VADER Moderator
    Staff Member

    Joined:
    Jan 16, 2008
    Messages:
    2,605
    Likes Received:
    1
    Log On
    this wil get you to american power sports I think but you can google the name and look for tachs digatron 30 or 40 series they are not cheap!
    here is a tach and head temp gauge from American power sports GoKart racing
    its not cheap but a very rugged gauge I have one on my racing kart. I haven't raced the kart in a couple of years so I might take it off the kart and put it on one of my bikes this tach will work on either 2 or 4 stroke engines it has a head temp sensor and a lot of features it will record your highest rpm and head temp etc. I know they cost more than the bike engine just wanted to let you all know what is out there. Turk brothers also sells them google racing karts you might be able to find this gauge for less money if you want to do some searching.
    Norman
     
  11. MikeJ

    MikeJ New Member

    Joined:
    May 3, 2009
    Messages:
    82
    Likes Received:
    0
    Here is another site: SenDEC Products Group - Home.

    Look at their Inductive Meters (Surface Mount). I ordered one today; the cost to my doorstep (product and shipping) is less than $48. A picture shows you wrap the pickup wire around the sparkplug wire. There is no stated voltage source. It appears that the inductive pickup wire also supplies enough energy to power the internal microcircuit. With velcro tape, I plan on making mine portable from one bike to another. They claim the meter is good for up to 8,000 rpm.
     
  12. BarelyAWake

    BarelyAWake New Member

    Joined:
    Jul 21, 2009
    Messages:
    7,209
    Likes Received:
    5

Share This Page