Separate names with a comma.
Discussion in 'Motorized Bicycle General Discussion' started by Fabian, Sep 30, 2009.
Isnt there a tac you can just hook up to the cdi or plug wire to work?
Problem is the engine is already geared down so the sprocket is not the same as the engine's RPM. Crankshaft = little gear and clutch = big gear.
Yes you can hook up a tacho which works of the sparkplug lead but it costs more than a $15 K-mart pushbike speedo and $3 worth of heatshrink tubing.
I've already done the maths and worked back through the jackshaft ratio and the engines primary reduction gear ratio (big and small gear) to tell the bicycle speedo what circumference it needs to be using for an accurate readout in kilometers per hour, that reflects engine rpm.
Just do my conversion, follow the instructions and you'll be amazed that the bicycle speedo reads the engine rpm correctly.
I've taken my bike to three engine shops and they've confirmed with their electronic tacho's hooked up to the sparkplug lead that the bicycle speedo is in fact reading the correct rpm's
Just do the maths yourself and you will understand how it works and why it works - "there is no problem".
there has got to be a simpler tack...is there some way of using those primary ignition circuits already on you handle bars(your kill switch)....other than that i got a timing light with a tack...its inductive off of the secondary ignition...a normal car tack works off the primary ignition...there has got to be some kind of product out there for single cyl. 2 strokes...
Maybe there is a more simple tacho but if you can find one for under $20 that doubles as a spare pushbike speedo and also holds max rpm and average rpm, please let the rest of us know.
There are tractor/lawnmower units that cost about the same as these speedos. I bought a half dozen a couple years ago and they work great. Unfortunately no links ATM.
The "Tiny-Tach" brand are mostly for planes and outrageously overpriced.
$36 for a proven, quality, and multifunction tach isn't really "outrageous" - tho I can see merit and certainly respect the do-it-yerselfer, even saving a few bucks but you really need a touch of perspective lol Have you priced replacing the entire tach unit on a new Honda motorcycle, or even just a taillight lens? heh, these TinyTachs are a great product for those that just want to stick a good, reliable gauge on their bikes w/o fuss or hassle.
Another way of lookin' at it is $15 bucks or so fer yer parts + say $10 per hr labor rate = about the same price as a TinyTach. The only difference being the justifiable pride in making something yourself.
They're for far more products than just planes lol - perhaps you've been shopping in all the wrong places The reason they're so popular amongst ultralight aircraft owners is their absolute reliability - an airplane is no machine for failures and a tach is a critical instrument for flight.
Tiny-Tach: Gasoline Tachometers
Certainly outrageous for bike when it costs half as much as a new engine. And you can get units with similar function for 1/3 the cost.
Maybe SOMEBODY owns stock in Tiny-Tach factory?
Nope - I jus like 'em and there's folks like this;
I gotta point out that these awesome bike engine kits @ $150 really skews a budgetary perspective - I've fallen victim to that myself lol
Gawd - I remember buying both marine and real aircraft parts, if you want truly outrageous prices lol Even just actual motorcycle bits really can put a hurt on the 'ol wallet!
edit: Despite all my going-on bout TinyTach, I still haven't gotten one fer my bike yet. If ya could manage to dig up a link or two for these "$10 tractor tachs" I'd be more than happy to check 'em out - not like I wouldn't mind savin' a few bucks myself lol, I've just NEVER seen a $10 gauge worth buyin'
Unfortunately I'm at the vacation house now waiting for foliage to change. Won't get back home for a couple weeks (another 300 mile BIKE trip). I'll see if I can find an invoice or read labels then. There were 2 models, one about $15 shipped and another slightly smaller and cheaper. Meanwhile Google is your friend (maybe ).
Engines kits in Aus range from $200-$350 depending on where you shop. I am actually keeping my eye on some 99c auctions on proper tachs at the moment though to see if I can score a bargain. If not I'll be building one of these myself.
Couple minutes of Google at local library came up with what I think is mine:
Item # LCD8010Y07, LCD8010Y Self Powered Engine Tach/Hour Meter sparks every other engine revolution on ENM Company
Says single $25 but a few guys at the airport got together and bought them for about half that. IIRC the half dozen I ordered came to $85 shipped. Certainly a fraction what I paid for Tiny-Tach (not so tiny price).
Certainly it's a good price and the sample time is reasonable - although not really relevant for a tacho (but i like the feature and it's important to me) it doesn't hold max rpm and average rpm.
In Australia, i haven't found a small compact tacho for under $80, some priced as high as $250
A $20 pushbike speedo calibrated to accurately read RPM with features that the others don't have, was an option too good not to experiment with or pass up.
I kind of glanced at this post on the home brewed tach. I'm wondering why you couldn't attach the speedo pick up right on the mag coil so the sensor could pick up the magnets on the rotor as they go by? There is enough space on the mags. coil at the back where I mounted a home made coil to power up an extra head light.
I don't know if the speed sensor will work there with the rf that the engines put out but its just a passing thought maybe one of you guys might want to give it a shot?
I suggested that in post #5. The sensor (reed sw) works but unfortunately range of calibration on my unit did not allow useable RPM readings.
i love tacos.
would 5 inch range work if i where to put the sensor by the magneto
i dont know about the voltages put out by the manito compared with the voltages induced into that tach's sensor but it sounds like they do the same thing so why wouldnt the coil primary wires work???other than voltages