Well kzbesner, when you say "about to die any day now" that should be a pretty good indicator of the engines over all condition.
A NO2 kit will only blow a tired motor up.
I've experimented with NO2 kits over the years, and ive found they can be used with success IF you remember to add extra fuel as well.
These engines are rebuild able, might I suggest you buy a quality rebuild kit for that engine and also buy a new engine only.
The rebuild could be your NO2 engine and the new one can be your spare should anything go wrong.
Also, there is a safety issue... these thing can and do explode... NO2 will only hasten that possibility with possible catastrophic results , not only to the engine but to you as well.
Throttle cables are inexpensive, get a new one.
If you insist on saving the old one, I use a method for shortening my throtle cable to the length I want.
If its a stainless steel cable you will need a few things to repair it.
A propane torch,
Real silver solder,
Quality soldering flux,
and a fine grind stone or files.
#1- Unscrew or unbolt the top of the carburetor.
#2- PAY attention to the arrangement of the cable noodle("J" tube) spring and the brass carb slide.
#3- Remove the slide and spring and noodle from the cable and put them someplace safe so you wont loose them.
#4- If you have any slack in the cable housing, now is the time to measure and cut it to the proper length.
#5- Once you have the housing cut to length, examine the cable, is it still in good shape? if so your golden.
measure the cable its self, be sure to leave yourself a few inches of slack, you don't want the cable to short.
#6- I use a good quality cable cutter as a good clean cut is mandatory for this to work properly, be careful as not to let the cable unravel.
I slip a cable end ferule on to the end of the cable first, then the noodle, then the slide, you should have about 1" to 1 1/2 inches of cable showing.
#7- now for the tricky part, dip the end of the cable in the soldering flux, have the torch and solder ready, GENTLY heat the end of the cable and quickly applie solder to the very end as to build up a nice fat bead of solder, only silver solder will stick to a stainless steel cable, DO NOT over heat the cable! now you should have a nice fat bead on the end of the cable ready to shape.
#8- I use my bench vise for this next part, let the cable end fully cool, I gently clamp the end in the vise with just the new bead of solder showing, then very carefully I file the bead down to fit neatly in the slide, this might take a little time, go slow here keep checking the slides fit until your satisfied.
#9- Now reinstall the spring, this is your only throttle return spring, I like to use a slightly stronger spring to assure the throttle snaps shut when you roll off the throttle, slip the spring back on to the cable between the
slide and new cable end bead. and re assemble the top of the carb. TEST it first! work the throttle several times BEFORE trying to ride.
This is a good method to keep your cables the right length and looking clean.
Good luck.
BBB