coleman starter not cranking fast enough?

I have a used coleman starter for kt100 and the basic way to start it was to find random pieces of wire and touch them to the solonoid/starter to the battery,pretty billy bob style actually so I decided to take some jumper wire with aligator clamps attached and solder them to the coleman/solonoid.

after all said and done the starter doesnt spin fast enough with a fully charged battery and the cable gets hot as hell,seems like a serious voltage drop and looking at the cheap jumper cable its super super thin I cant believe its used as a jumper wire even,non the less its too small what would be a recommended wire diameter for these coleman starters?I was thinking maybe 6 guage or even 4 guage but not sure,it will only be 2x 6' long cables what do you think would be a good size,im sure bigger is better but i dont wanna lug around 20lbs of cable let me know thanks guys.

heres a pic of the wire i used lol you would think JUMPER cable would be cable not a few threads of wire...

Yea you really got to check them jumper cables before buying, otherwise may as well use a drop cord.
my coleman starter with a lawn and garden battery starts the kt just fine. its at least 12 years old, prolly the 5th battery.
may need to disassemble and oil the bearings and check the brushes.
Any way I think .8 or 10 gauge would be sufficient.