What causes Reed valves worn or broken on the Yamaha Banshee 350 (YFZ350)?

Listen for rattling, inspect reeds for cracks or warping Estimated fix cost: $40-$80

What causes Seized or scored cylinder/piston on the Yamaha Banshee 350 (YFZ350)?

Pull plug, check compression, inspect for smoke on startup Estimated fix cost: $150-$400

Rough idle, bogging under throttle, uneven power delivery Estimated fix cost: $20-$80

Idle surging, hard starting, engine runs lean at idle Estimated fix cost: $100-$250

Known issues to inspect before buying a used Yamaha Banshee 350 (YFZ350). What to check and how much repairs cost.

SERIOUS

Listen for rattling, inspect reeds for cracks or warping

Fix cost: $40-$80

SERIOUS

Pull plug, check compression, inspect for smoke on startup

Fix cost: $150-$400

MODERATE

Rough idle, bogging under throttle, uneven power delivery

Fix cost: $20-$80

SERIOUS

Idle surging, hard starting, engine runs lean at idle

Fix cost: $100-$250

☐Test ride and check for bog or hesitation

☐Compression test both cylinders, expect 120+ psi

☐Inspect frame for cracks near engine mounts

☐Verify spark plugs are clean, not fouled or white

Bulletproof if maintained, neglect kills it fast