What causes Valve seat wear, tight intake clearances on the Honda Crf 450r?

Cold valve clearance, hard starting, top-end noise Estimated fix cost: $400-$1200

What causes Unicam cam chain and tensioner wear on the Honda Crf 450r?

Rattle at idle, chain slack, service records Estimated fix cost: $200-$600

Crusty residue at pump weep hole, milky oil Estimated fix cost: $60-$200

Dirt in airboot, filter condition, compression test Estimated fix cost: $800-$2000

Known issues to inspect before buying a used Honda Crf 450r. What to check and how much repairs cost.

SERIOUS

Cold valve clearance, hard starting, top-end noise

Fix cost: $400-$1200

MODERATE

Rattle at idle, chain slack, service records

Fix cost: $200-$600

MINOR

Crusty residue at pump weep hole, milky oil

Fix cost: $60-$200

SERIOUS

Dirt in airboot, filter condition, compression test

Fix cost: $800-$2000

☐Leakdown or compression test before buying

☐Inspect valve clearances yourself, cold engine

☐Check hour meter versus maintenance receipts

☐Look for frame cracks, subframe, mounts

Reliable if maintained; brutal if hours neglected