Crankshaft

For main bearings and oil seals click here; for alternators and fittings click here.

Do not try to remove the crankcase end doors without the correct tool as this is virtually impossible without it, click here.

Exchange Crankshaft Assemblies.

As well as the obvious wear that takes place in the big end bearing of the Arrow and Leader crankshafts, wear is usually also found to have occurred on the mainshafts where the main bearings and the centre oil seal run. Once the bearing becomes loose on the shaft, wear is accelerated, vibration increases and primary compression is lost as the seals wear. Replacing the seals and bearings does not cure the problem as they just wear out again, in some cases as soon as 2,000 miles.

To check for wear, slide a good, preferably new, bearing onto the shaft to its correct position. It will probably be quite tight to fit initially on the unworn portion of the shaft but slide on easily as it arrives at the portion of the shaft where it usually sits. If it slides by hand or the inner race can be turned on the shaft it has failed the test and should be exchanged for a reconditioned crankshaft. Also check the left half of the right hand crank where the centre seal runs as the oil seal will wear a groove at this point and this should also be repaired. Also do not forget to check the loose collar for the right hand outer seal. 2 stroke engines depend on good primary or crankcase compression provided by the crankcase oil seals.

Wear in the big end bearings is usually easy to detect but it should not be possible to feel any up and down movement. Some rocking from side to side is permissible. If in doubt as to the condition of your crankshaft we will gladly inspect and advise without obligation.

All exchange crankshafts are pressed together and trued with new big end assemblies and good shafts. As very few shafts arrive that are the correct size the exchange shafts have almost always been reclaimed by grinding undersize and plated with hard chrome before being ground to close tolerances. This ensures that the bearings are a perfect fit and the engine will work properly and last for years.

We can overhaul your own crankshafts if wished but this may take some time while we wait for the next batch of shafts to be done. We can also just replace the big ends and true the assemblies without replacing the mainshafts.

Part No

Description

Per

Model

S5-6

Internal shakeproof washer, alternator bolt 1 All

T18/13

Small end bush for Suzuki pistons 2 All

T19/1

Flywheel and engine sprocket 1 All

T22

Engine sprocket 1 All

T29

Crankshaft centre bolt 1 All

T30/1F

Con-rod with new crankpin, rollers and NO small end bush. Please order the small end bush separately. EXCHANGE N.B. These are matched assemblies do not swap parts about. – Knife edge type 2 All

T30/2F

Con-rod with new crankpin, rollers and NO small end bush. Please order the small end bush separately. EXCHANGE N.B. These are matched assemblies do not swap parts about. – H section type 2 All

T31

Small end bush for original or Hepolite pistons 2 All

T44

Washer, crankshaft locking bolt 1 All

T45

Key, centre bolt 1 All

T58

Collar for right hand oil seal in outer cover 1 All

T75

Lockwasher, engine sprocket nut 1 All

T76

Engine sprocket nut 1 All

T79

Key, engine sprocket to crankshaft 1 All

T80

Key, flywheel to engine sprocket 1 All

T89

Bolt for alternator rotor 1 All

T98

Key, alternator rotor to crankshaft 1 All

T103

Right crank, big end only replaced and trued EXCHANGE 1 All

T104

Left crank, big end only replaced and trued EXCHANGE 1 All

T105

Circlip, centre bolt 1 All

TW-33

Plain washer, alternator bolt 1 All
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