Hi Robert T,
When you go to Radio Shack look for the heavy duty coil cord.
I've used it for over 2 years now and have had no problem.
I also use it on my booster to kick start stuck compressors in A/C units.
You don't need 10 ga wire.
Even the starters come with 16 ga.
Look for the coil cord they sell for testing gear like an amp probe.
If the enging has a hydro static lock then you will feel the wires warm up after 10 seconds.
But under normal conditions 16-18 ga will do fine.
I also have a home made starter from a 12 volt bike generator.
I only have 20 ga wire on that and it cranks the 40 and 46 LX engine with no problems
I never saw 10ga coil wire