CHAIN & SPROCKETS

How to inspect chain tension:
Warning: Never inspect drive chain while engine is running

1. Switch off engine and put into neutral.
2. Position the bike on it's centre stand.
3. Place the chain slack gauge against the reference
   arrow on lower edge of the swingarm as shown.
4. The top of the chain pin should align with the B line.
   If it's above A then the chain needs to be loosened.
   If it's below C then the chain needs to be tightened.
   

Note: If the lower chain slider rubber block is missing
it might affect the accuracy of the chain slack gauge (The
bolts that hold the rubber block in place also hold the
side stand in place on the NT400J)

Alternative method.

1. Sit on the bike facing backwards. Compress the rear
   suspension as much as you can (or get someone to sit on
   the bike).
2. If the chain feels loose then it needs to be
   tightened. Tighten the chain until it starts to get
   a little firm (while someone is sitting on the bike).
   












3. DID recommend 3/4" (20mm TO 25mm) of slack while the
   rear suspension is compressed enough to cause the chain
   to be at it's tightest, the chain will be at it's
   tightest when the rear wheel axle, swing arm pivot and
   the front sprocket axle are all in line, like in the
   picture above.
4. The slack is measured by pushing the chain up
   fairly hard with your fingers and then pulling it
   down fairing hard, the distance between these points
   should be 20mm.

How to tighten the chain.

1. Switch off engine, put into neutral, position bike
   on centre stand.
2. Loosen rear eccentric bearing carrier pinch bolt.
3. Turn rear eccentric bearing carrier clockwise with
   an eleven centimeter C-spanner (Hook spanner) until
   desired tension is achieved.
4. Tighten rear eccentric bearing carrier pinch bolt to 75Nm.

faults.

• Worn or defective chain.
  

  When an O Ring chain reaches the natural end of it life
  it starts to wear much quicker, Sometimes they develop
  a tight spot or some other defect. Sometimes one link
  on the chain wears much faster that the other links which
  can cause a click sound when accelerating. Sometimes
  even a new high quality chain can develope stiff links,
  Strictly speaking the chain should then be replaced.

• Worn or defective sprockets

  Some low quality sprockets can be defective when new or
  develop a defect as they wear. You should only use
  sprockets from a reputable manufacturer. Look at the
  picture -> to see examples of sprocket wear or damage. If the sprocket teeth show any sign of "hooking" then they
  should be replaced when replacing the chain.

• Incorrect chain tension.

  Too tight a chain can damage the splines on the
  countershaft and bearings. Too loose a chain can
  cause kicking which can damage the chain.

• Chain has a tight spot.

  Check the chain tension, then rotate the chain and
  check the tension again, repeat this until you have
  checked the entire chain. If there is a difference
  in slack then the chain has a tight spot and needs
  to be replaced. I'd guess that a difference in slack
  of more than 10-15 mm is a problem.

• Bad bearings.

  Check rear wheel bearings, rear sprocket carrier bearings
  and swing arm bearings.

• Worn final drive dampers

  Check to see if the rear sprocket can be turned a little
  without turning the wheel, If there is free play then
  the rubbers need to be replaced.

• Worn splines on countershaft.

  Usually caused by improper chain tension or severely
  misaligned sprockets.

• Damaged or missing teeth on the bearing carrier.

  Usually caused by adjusting the chain tension with a
  hammer and screwdriver. It might be possible to weld
  new teeth to the carrier or make a special tool that
  can reach around to good teeth.

  
• Chain lube.

  Honda recommend the use of 90W gear oil to lube the
  chain, however it's very messy. Drier chain lubes are
  available, however the drier lubes don't lubricate as
  well as the oily ones resulting in shorter chain life.

• Special tool.

  I made my own 115 mm C-spanner by using one of those
  large octagonal spanners for removing the heating
  element from one of those large copper water heaters.

Trouble shooting

A click or knock sound comes from the chain during acceleration.

• Defective sprocket.
• One link on the chain is badly worn while the other links are not worn.
• Missing or worn O-Ring
• Chain has a tight spot.

Grinding sound from chain.

• Chain has a tight spot(s).
• Rubber O-Rings may be missing from the chain.
• Severely mis-aligned sprockets.
• Badly worn sprocket(s).
• Loose sprocket(s).
• Chain too tight.

Chain wearing too fast.

• Mis-aligned sprockets.
• Chain too tight or too loose.
• Insufficient or improper lubrication.

Chain kicking.

• Chain is too loose.
• Chain has a tight spot.

Sprockets wearing on one side.

• Mis-aligned sprockets.

Worn gearbox output shaft.

• Mis-aligned sprockets.
• Chain too tight or too loose.

Mis-aligned sprockets.

• Improperly fitted sprockets.
• Worn swing arm bearings.
• Worn wheel bearings.
• Worn sprocket carrying bearings.
• Bent swing arm.