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.


Trouble shooting

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

Grinding sound from chain.

Chain wearing too fast.

Chain kicking.

Sprockets wearing on one side.

Worn gearbox output shaft.

Mis-aligned sprockets.