You would need a lot more information than just a vague description of a single symptom to figure out what parts needed to be adjusted or replaced.
yes
The dry weight for a 1997 Yamaha 25 hp is listed at 108 lbs.
1997
no
1997-2001
400 cc Yamaha engine
yes the crankshafts are the same
The suggested spark plug gap on a 1997 Yamaha YZ 80 is .036. That is the standard gap for most Yamaha small engines.
What causes a 1997 Pontiac sunfire gt with a 2.4 liter engine to stall when stopped at a light
24 to 1
17 hp
aproxamently 1200 $