550RH (Seca/Euro)

Camshaft, chain and sprockets

1. Camshaft

a.   The cam lobe metal surface may have a blue discoloration due to excessive friction. The metal surface could also start to flake off or become pitted.

b.   If any of the above wear conditions are readily visible, the camshaft should be replaced.


A. Battery

1. The fluid level should be between the upper and lower level marks. Use only distilled water if refilling is necessary.

Normal tap water contains minerals which are harmful to a battery; therefore, refill only with distilled water.

Pick-up coil, Generator and Starter

Pick-up coil assembly

1. Remove the alien bolt that holds the timing plate.

2. Remove the pick-up coil securing screws and remove the pick-up coil assembly.


Insufficient compression pressure will result in performance loss and may indicate leaking valves or worn or damaged piston rings. Procedure:

1.    Make sure the valve clearance is correct.

2.    Warm up the engine 2^3 minutes.

3.    Remove all the spark plugs.

4.    Install a compression check gauge.

Crankcase Assembly

Crankcase assembly

a. Apply Yamaha bond # 4 sealant or equivalent to the crankcase mating surface. Be very careful not to allow any sealant to come in contact with the oil gallerly "O-ring" and crankshaft bearings. It is extremely important, however, that sealant be applied around the case stud holes. Apply sealant to within 2~3 mm (0.08 - 0.12 in) of the bearings.

Cylinder head and Camshafts

a. Install the new cylinder head gasket. Install the dowel pins and "o-rings".

b.   Install the cylinder head onto the cylinder. Pull the cam chain through the cylinder head as it is installed. Tie the cam chain so that it does not fall into the crankcase.

Transmission, Starter clutch and Seals

Inspect each shift fork signs of galling on gear contact surfaces. Check for bending. Make sure each fork slides freely on its guide bar.

2.    Roll the guide bar across a surface place. If the bar is bent, replace.

3.    Check the shift cam grooves for signs of wear or damage. If any profile has excessive wear and/or damage, replace cam.

Cylinder head and Cylinder

Cylinder head cover

Place head cover on a surface plate. There should be no warpage. Correct by re-surfacing as follows:

Place #400 or #600 grit wet sandpaper on surface plate and re-surface head cover using a figure-eight sanding pattern. Rotate head cover several times to avoid removing too much material from one side.


1. Brake adjustment

a. Front brake lever free play adjustment

The brake can be adjusted by simply adjusting the free play of the brake lever. The piston in the caliper moves forward as the brake pad wears out, automatically adjusting the clearance betweenthe brake pads and brake disc.

Cam Chain Adjustment

The cam chain becomes stretched with use, resulting in improper valve timing and engine noise. To prevent this, the cam chain ten-sioner must be adjusted regularly.

1.    Remove the timing plate cover.

2.    Slowly rotate the crankshaft counterclockwise until the "C" mark on the timing plate aligns with the stationary pointer.