Engine and Transmission

Repairing Second Gear

Note: this fix does require mechanical ability and judgement. If you have never done anything like this before, you may decide to disassemble the transmission yourself (hey, everyone has to start somewhere) but I suggest you seek out the assistance of someone with some mechanical experience once you get inside. Just changing/repairing the gears may not be enough.

Problem: The transmission kicks and jumps out of second gear, under load. This rapidly gets worse and soon the bike won't take second gear at all.

Tags:

Cylinder, Head and Valves

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.

Cylinder head

Middle Gear

MIDDLE GEAR/DAMPER

a. Middle gear lash 0 2 mm (0.008 in)

d. Measure the gap between the driven gear bearing housing flange and the crankcase with a feeler gauge. This is the shim size required.

Pistons, Cylinder and Head

11. Pistons and cylinder

a. Install the pistons on the rods. The arrow on the piston must point to the front of the engine.

NOTE: Before installing the piston pin clips, cover the crankcase with a clean rag so you will not accidentally drop the circlip into the crank-case. Always install new piston pin circlips.

Transmission, Clutch and Middle gear

TRANSMISSION

3. 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 gallery "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.

Upper Crankcase Assembly

CRANKSHAFT/PISTON

. WHEN INSTALLING THE CONNECTING ROD. BE SURE THAT THE SECURING NUTS ARE ON TOP.

Engine assembly

Shifter, Generator, Starter and Pickup coils

7, Shifter assembly a. Install the shift shaft assembly with the stopper lever.

b. Install the shift lever assembly with the positioning spring is properly located on the stopper pin and the teeth should be set properly as shown.

Engine Specifications

1.

a. b.

Cylinder

Head Volume
Warp Limit

 

 

Reinstalling Engine

Remounting engine

1. Assembly is the reverse the applicable removal steps.

CAUTION: Always use new bolts in the drive shaft coupling.

2. Install and tighten the engine mounting bolts-

Engine mounting bolt torque: 8 mm bolt:

20 Nm (2.0 m-kg, 14 ft-lb) 10 mm bolt:

Cylinder, Head and Valves

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.

Cylinder head