BOYESEN Reed Petals for OEM reed valve for YAMAHA YZ 125 1988-1992

On YAMAHA YZ 125 from 1988 to 1992, the BOYESEN BOY604 set of reed petals fits in place of the original part. The reeds control the intake of a two-stroke engine. Over the hours, the petals tire, split or fray at the tips: the engine responds less well to the throttle and is harder to start.

Key features

• Designed to fit the stock reed block.
• Designed for Boyesen reed blocks.
• Made in the USA.

Specifications

• Brand: BOYESEN
• Manufacturer part number: BOY604
• EAN code: 804429002924
• Engine: 2-stroke

When to replace it?

• Petal tips chipped, split or frayed.
• Petals no longer sitting flat on the cage (visible gap).
• Weak pick-up at low revs, hard starting.

Inspect the petals at least once a season and at every piston change; replace them as soon as a tip is damaged.

Fitting tips

1. Remove the reed valve block and clean the cage.
2. Fit the petals the right way round and tighten the petal screws with threadlocker to the recommended torque.
3. Check that the petals sit flat on the cage before refitting.
4. Refit with a new reed block gasket.

Why BOYESEN?

Boyesen is an American brand specialising in the intake and the engine covers of two-stroke engines: reed petals, RAD Valve reed blocks, engine covers and Supercooler water pumps.

Spare parts and items to plan

• Reed block gasket : BOYESEN · V FORCE
• Spark plug : NGK 3530 · NGK 3230
• Carburettor repair kit : ALL BALLS 46-5019 · ALL BALLS 26-1145

Frequently asked questions

Do I need to re-jet?
Usually not on a well-tuned engine; check the colour of the spark plug after the first few rides.

Compatibility

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

Fits:
YAMAHA YZ 125 1992
YAMAHA YZ 125 1991
YAMAHA YZ 125 1990
YAMAHA YZ 125 1989
YAMAHA YZ 125 1988