As the Speedo is in an awkward position to view with a full face helmet.
I am considering fitting a bicycle speedo, On a Google Search a guy has fitted one to an enfield, and he said not to use a wireless one , but did not say why.

Has anyone on this forum done it? and what did you use? etc

Yes, don't use the wireless, I think the ignition causes enough interference for it not to work.

There's also several other kind.  The bicycle sigma being on the bottom rung as far as cost.  I have a Veypor VR1, you can get from lancer.  Also I think in the market place a "VR" ? for $100 to $200, not only a speedo, but tach, time, temp and several other options for monitoring engine temp or pressure.  

Trick to putting in a electric device that is wired is to use a supermagnet on the top surface of your rim with the pick up coil mounted on the underside of your fender (there's a mount flange there that is all nice and neat and out of sight).  Doing this trick means the stock length of wire they give you works out perfectly -- you don't need to add wire to it.

You can mount your sensor under your fender next to the edge of the rim and put one (or more if needed for the weight) of these magnets on the top of the rim  (narrow side out)  exactly opposite from the air stem so as to not affect wheel balance adversely.  This magnet is a "lengthwise" oriented magnet so it projects the strongest field distance from the narrow ends.

The Sigma 506 unit is neat for our use because the wire length works out to be exactly what we need on a Savage when we do it with this stronger "sender" magnet to make the tucked under the fender across from the rim mount position for the sensor work correctly.  Buy yourself at least 4 of the little magnets, because they double as BALANCE WEIGHTS for your tires (and they cost a lot less than the chrome plated lead spoke weights they sell for $7.00 EACH)

http://www.supermagnetman.net/product_info.php?products_id=346



Do use the mile marker setting trick on the black background web page referred to below.  If you take a trip on an interstate just stop at a mile marker and restart your computer as per his directions and write down all the info you get when you stop at a goodly distant mile marker.  Mile markers are not dead nuts accurate as individuals, but when you are averaging say 40 to 100 of them you get a very very accurate setting for your speedo computer.  

Here is the calculator that makes all this math and mm-to-mph translation dirt easy.

http://www.geocities.com/toms_toys/bc80c.html


Remember, same magnet can be used as a balance weight for your front tire.  I currently use 2 as that is the correct counterbalance weight  to the valve stem that I need for my newly mounted hard rubber front tire.  

Here is a picture to show you the "easy way" to do it using the stock cable length and a dab of epoxy on the edge of the fender bracket (totally hidden from view).  

Some folks like to splice in some extra wire and run the wire all the way down to the brake rotor to mount their sensor. This amounts to good bit of extra work, is readily visible and does nothing to aid in the properly balancing of your front wheel assembly.  

Some have even built aluminum brackets to hold their sensors down by the rotor -- a lot of extra work went into that one.

i've got a sigma but havent put it on yet.  then i can turn the hole into a cupholder or maybe a secret compartment.   well now that i've said it, it's not secret  

* sluggo