There are several different systems for "compression release" on engines. Some engines only "reduce" the compression - while still retaining enough compression to allow the engine to start. These systems can be operated by a hand lever - or are sometimes activated by a small movable weight on the camshaft. On the lever systems there is usually a small orifice that allows only a small portion of the exhaust to escape - or there is a little hole part way up the cylinder that is then closed off when the piston passes above the hole. My big chainsaw has a compression release "button" on the top of the cylinder - you push it in and it releases a small amount of compression, and when the engine starts the force of the explosion forces the button into the closed position. For the camshaft operated systems - when the engine is not running the exhaust valve is held open a little longer by a pin or ramp, and by releasing the compression out the exhaust valve for a portion of the compression stroke the compression is reduced.....then when the engine starts the weight moves outward on the cam and the exhaust valves work normally. Most lawn mower engines have this system, and a lot of motorcycles use this camshaft operated system as well....and you don't have to do a thing as it is all automatic.
The compression release on the Savage holds the exhaust valves open so far that the engine will never start or run - and the electrical release only functions long enough for the engine to turn over once or twice and build up some momentum to ease the work of the starter. When you remove the electrical system you need a way to hold the exhaust valves just long enough for the starter to turn the engine over to build up some momentum - then you have to release the lever for the engine to make compression and start.
The lever up on the handlebars is half of the system....the part down on the engine has to be compatible with the lever.
Buying and using the handlebar lever from another bike has some problems. Most of the bikes that use a compression release lever have 7/8" diameter handlebars - while the Savage is a 1" diameter bar. I switched my bike to use 7/8" diameter handlebars, and I tried using a Honda CRF450 clutch lever with a "Hot Start" lever built into it. The 2 problems I ended up with is the clutch lever did not have a long enough pull to get the Savage clutch to release completely, and the Hot Start lever did not have enough leverage to pull the compression release shaft on the Savage. IF the exhaust valves happened to be open when you pulled the lever it worked fine....as the valves were already open and you did not have to lift them off the seats. If the exhaust valves were closed the lever just couldn't be pulled hard enough to overcome the valve spring force to open the valves.
I ended up using a BMX bicycle left brake lever, and I had to modify the compression release lever down on the engine to provide a longer lever that provided more leverage and matched the cable pull length of the BMX lever. It also required a new cable mount to move the cable end in line with the longer lever, and I had to build a cable.
And now a plug for a future sale. I have found a way to bore the hole in the BMX lever to fit the 1" handlebars, and I am making 5 kits to install this manual compression release. I have not yet established a price, as I need to finish the kits and see how much money and time I have in them. It does take a lot of time....probably about 4 hours for each kit plus parts cost. I had to make all the cable ends, make a holding jig for boring the levers to 1", cut the cables to length and solder the ends on, make the longer levers for the engine, and either make of modify the cable mount (not sure yet which way to go). I have all the parts purchased, the levers have been completed, and I will have the engine related parts and cables finished in about a month.