Far as I know , no fuel injections been done but Lancer sells a vm carb kit that will dramatically improve performance, get his cam too if you can.
You'll not believe the difference.
Seviersavage

EricTheRed wrote on 09/06/09 at 05:23:07:


There are options for gaining more performance, and they depend on what you want to achieve, what you want to do work wise, and how much you are willing to spend.
The typical mod is to replace the stock muffler with a dyna or sportster unit and rejet the carb to match, with the engine remaining stock.

If you want to go beyond that and use a higher flow muffler like a Supertrapp or Jardine, then you can benefit from a more performance oriented carburetor.  There are several to choose from.
Mikuni VM roundslide or TM flatslide;  Keihin round or flatslides, though a bit higher priced than Mikuni's; Edelbrock Quicksilvers which are also high priced if new, but can be found on ebay at times for good prices.

For a stock engine I would recommend a 36mm carb, or 38mm at most.  A stock engine with stock header, even with a high flow muffler, restricts total exhaust flow.  With that in mind, a 36mm sized performance carb is best suited for a stock engine.  
If the engine and/or header are modified then a 38mm will fit the bill.
Your best bet for a header is 1.5" ID, or 1.65" at most.  Anything bigger and you will loose power.

The Mikuni roundslide is the best bang for the buck.  They are inexpensive to buy, new or used, and parts/jets etc are cheap and plentiful.  That is why I use them in the Performance Carb Kits.

If you wish to take a look at what I've put together, here is the link:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120449278314&vi...

If you want or need to try to put together something on a shoestring budget then watch ebay for carburetors; some can be found for very low prices if you are patient.  Keep in mind that you will need a new rubber mounting flange for the carb since the size varies, and a custom throttle cable is also required.
Of course, the jets and needles will need to changed to match the requirements of the Savage/S40 engine.  
A carb setup can be done for $150 to $200, depending on how many of the jets need to be changed.  If you got a used carb that happened to be setup for a 2 stroke racing bike (lots of those on ebay) then every thing will require replacement except the carb body itself, and maybe the slide, but the needle jet, needle, pilot jet, main jet, air jet, and needle valve will all require relacement if you want a proper setup for the Savage engine.  It would also be wise to replace the bowl gasket and check the float setting as required for a 4 stroke engine vs 2 stoke.
The 2 stroke engines typically use almost 2x the fuel compared to an equal sized 4 stroke.

good luck with your project ... just holler if you need more help; lots of folks here have made an assortment of carb performance mods

Part of my life is living on ebay.    When you have a shopping list and can take the time, ebay is a terrific source.  
Both of my Savages have Progressive 418 shocks, one black set with less than a 1000 miles on them when purchased for $125 incl shp.  The other set are chrome and purchased new in the box for $60 + shp.  These shocks normally retail for $400+


There are all sorts of things that show up on ebay that are useful for a Savage build.  I look for parts that are 10 cents on the dollar, but will on occasion go up to 50% if it is something I really need for myself.  I never go beyond 50% of retail.

The VM is no larger than the stock carb, but the throttle cable does mount through the top of the carb  vs the side attachment for the stock unit.  But that does not present a problem when mounting'