Yes, Sigma bike computers work fine. Punch it into the search engine to find all the threads.
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This is a cut from one of the threads you will find
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1181496112Any tire that is larger or smaller in diameter than the stock IRC rear tire will result in speedometer error. This is additional error on top of the natural speedo error that we all have on our bikes.
(don't let kph and km fool you, you select mph and miles in the setup menu)
You can get an independently settable, waterproof, durable, easy-to-set-up digital speedo for $15 bucks that does an excellent job of telling you the truth about your real speed and distances traveled. Best source right now for this little jewel is LL Bean.
http://www.llbean.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=1&cat...
Instructions on how to set the speedo up can be found on this excellent web page. Don't be fooled by the different model numbers, the same company makes both and your 506 is a newer version of the same speedo this guy is talking about.
http://www.geocities.com/toms_toys/bc80.htmlLastly, you may need a source for a stronger sensor "sender" magnet that can bridge the larger air gaps between your motorcycle front wheel rim to the side of the front fender. You can mount your sensor under your fender next to the edge of the rim and put one of these 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=346Do use the mile marker setting trick on the black background web page referred to above. 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.
If you can't find it on the black web page, here is the calculator that makes all this math and mm-to-mph translation dirt easy.
http://www.geocities.com/toms_toys/bc80c.html