welcome to the Forum Earthman
It may be easier for right now to just route the cable the longest way you can so it
bows out in front of the bike and back to the throttle grip. You can get it
up and running and test everything this way without modifying it while it may be under some
warrenty terms with some vender.
A dremel tool with a fine adbrasive cutting wheel works well on cutting those stranded cables.
Cutting the lug off the carb end may cause the cable to roll up into the outer housing. No
worry if it happens as it can be delt with later. Now route your cable to the carb where you want it and remember to turn your handlebars hard to the left and right to see if you have
enough slack. (do this before cutting the housing) Measure twice and cut once. Just pull the outer housing out from the throttle grip so that when you cut it you won't be cutting the inner cable too .To cut where you have marked the housing, take a thin knife and cut thru the vinyl outer housing. Then take a pair of diagonal cutter pliers and ease them into the cut and squeeze. You'll be cutting one of
the windings that makes the housing structure. Have a nail that will fit into the housing handy to insert and size the opening. (so it's good and open) A sandpaper fingernail file will work good to
dress the opening and remove any burrs.
You'll likely have to pull the housing down from the throttle grip now and pull the cable out of
the spring loaded handle grip reel. Have a small modelers clamp ready now and when you get
enough cable out to come thru the end you just cut put the clamp on it and
shove the housing back into the throttle housing tight. You'll have nearly the extra foot
of moving cable exposed now at the carb end of the cable. (where you cut the outer foot of
housing off)
You'll need to cut the same amount of cable off to match the housing you cut off.
At this point you'll have to form a lug on the end of the cable like the one you cut off. It will have to be the same so it fits into the carb's throttle slide and not come off. You may find some of these
at a bicycle shop. These clamp on with a pair of pliers to squeeze them onto the cable.
"red" locktite would help hold it secure and dependable. You'll only need a drop and this is where
it may be a good idea to take it somewhere they have the materials to fit the lug onto the end of
the cable for you for a few bucks. If the new lug is larger than the original (make sure you keep
the original to compare it to) you'll have to sand it down by hand and make it fit properly. But once
you get it done like this you'll probably have a job out of it that you'll be satisfied with.
I would strongly suggest you fit it up first so you'll understand how it works if this stuff is all new to you.
But if I were doing it, this is how I'd go about it. Those small modeling knock off's of the Dremel
tool can be bought for less than $10 now and come with many cutting and grinding wheels and bits.
Some people mark the moving cable where they want to cut it with an ink marking pen and then put some soldering flux on the cable. Then take a small torch or soldering iron and heat it and melt some solder into the cable. When it cools they cut thru that. The solder serves to bind the strands of wire
in the lead solder so it won't fray. This is an old trick and works well.
Good luck and let us know how it works out.