Yamaha YZF-R125 Service Manual: Gaskets, oil seals and o-rings

1. When overhauling the engine, replace all gaskets, seals and O-rings. All gasket surfaces, oil seal lips and O-rings must be cleaned.

2. During reassembly, properly oil all mating parts and bearings and lubricate the oil seal lips with grease.

Gaskets, oil seals and o-rings


  1. Oil
  2. Lip
  3. Spring
  4. Grease
    Replacement parts
    Use only genuine Yamaha parts for all replacements. Use oil and grease recommended by Yamaha for all lubrication jobs. Other brands may be similar in function and appearance, but inferior in qua ...

    Lock washers/plates and cotter pins
    After removal, replace all lock washers/plates "1" and cotter pins. After the bolt or nut has been tightened to specification, bend the lock tabs along a flat of the bolt or nut. ...

    Other materials:

    Assembling the crankcase
    1. Thoroughly clean all the gasket mating surfaces and crankcase mating surfaces. 2. Apply: Sealant (onto the crankcase mating surfaces) NOTE: Do not allow any sealant to come into contact with the oil gallery. 3. Install: Right crankcase NOTE: Turn the shift drum segment ...

    Checking the radiator
    1. Check: Radiator fins obstruction clean. Apply compressed air to the rear of the radiator. Damage  repair or replace. NOTE: Straighten any flattened fins with a thin, flat-head screwdriver. 2. Check: Radiator hoses Cracks/damage Replace. 3. Measure: Radiator cap ...

    Throttle position sensor
    1. Check: Throttle position sensor a. Connect the digital circuit tester to the terminals of the throttle body sensor assembly coupler as shown. Positive tester probe → gray/red terminal "1" Negative tester probe → gray/black terminal "2" b. Measure the throttle pos ...

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