Batteryi have a john deere a LT155 riding lawn mower. when connecting ground there is an excessive amount of spark

shorten the links on either end of the connection

Here's the spark plug your John Deere needs. NGK Nickel Spark Plug BPR5ES 7734 Advance Auto Parts

1/2 x 60

Check all deck idler pulleys and make sure no bad bearings or flat spots

try this

if that is the Kohler 14 hp motor it may have the spark control untit on the motor cover. I recently ran into one like that and switched the coil out from a blown 20 hp kohler engine. I just taped up the excess wires and made sure they were not near any moving parts. The mower ran fine after that. Kohler wants about $160.00 for a spark control unit. There have been no repercussions since making the switch.

I had a similar problem lasy year.
Try this:
As soon as the machine seems to be stalling, loosen the gas cap.
If the engine continues to run, clean the gas cap vent hole(s).
Gary

need wiring diagram for john deere lt 155

I have googled LT155 and came upon john deere LT155 lawn tractor(noncurrent). It took me to John Deere's site. I put in your model number and it had several catagories. I would try the alphabetical list, go to B and look for traction belt.
Good day.

CK THE FLYWHELL KEY

u can change belt yourself need belt size and have to remove cutting deck but check belt tension first if loose with brake off belt stretched out and slipping needs replacement