Wössner Forged Piston for YAMAHA DT 250, TY 250, YZ 250 1974-1979

WOSSNER offers this piston kit for YAMAHA DT 250, TY 250, YZ 250 1974-1979. The piston slides in the cylinder and takes the force of the air-fuel combustion, passing it to the connecting rod and crankshaft.

Why choose a forged piston?

Instead of simply being cast, a forged piston is hot-pressed under very high pressure and then machined: its metal is denser and free of air pockets.

• Stronger when hot: it copes better with high revs, overheating and detonation.
• Lighter for the same strength: less stress on the connecting rod and bearings.
• Good to know: depending on the alloy, it expands a little more and is fitted with more clearance; slight noise when cold is normal.
• Why does it cost more? Forging tools, full machining and surface treatments cost more than simple casting.

Why choose WOSSNER?

Wössner has forged its own pistons since 1994: Molykote-coated skirt to reduce friction and ease running-in, kit supplied complete with rings, pin and clips.

When should you replace the piston on your YAMAHA DT 250?

Harder starting, loss of power, blue smoke, oil consumption or a knock when cold: these are the signs of a tired top end.

No manufacturer hour figure for this model. Cross-Mania guideline: compression check every 20 h in hard use and every 40 h for leisure.

Specifications and fitting tips

• Material: Aluminium
• Piston compression: Standard
• Rings Quantity: 2
• Stroke: 2T
• Forged piston
• Anti friction coated skirt

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore).

Cross-Mania tip: Measure the cylinder bore before ordering: the piston must match your cylinder size. Follow the manufacturer's break-in procedure and replace the top-end gaskets at the same time.

Also needed with this part

• Top-end gasket kit : CENTAURO · ATHENA
• Spark plug : NGK
• 2-stroke oil : LIQUI MOLY 1 L · LIQUI MOLY 4 L
• Air filter : TWIN AIR · TWIN AIR over-filter for FANTIC XE, XX…

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
YAMAHA DT 250 1979
YAMAHA DT 250 1978
YAMAHA DT 250 1977
YAMAHA DT 250 1976
YAMAHA DT 250 1975
YAMAHA DT 250 1974
YAMAHA TY 250 1978
YAMAHA TY 250 1977
YAMAHA TY 250 1976
YAMAHA TY 250 1975
YAMAHA TY 250 1974
YAMAHA YZ 250 1979
YAMAHA YZ 250 1978
YAMAHA YZ 250 1977