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.

How to check sprockets for wear.(Look at the picture)

Check the front sprocket shaft for wear periodically also.

Check that all the O-rings on the chain are intact, if not
replace the chain.

Check the chain for tight spots, if it has one: replace the chain.

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.

Honda recommend the use of 90W gear oil to lube the
chain, however, I use general purpose grease to lube
the chain and I apply it with a toothbrush shaped
plastic brush. I find it produces very little "fling
off" and it's a lot cheaper than buying those aerosol
chain lubes from the bike shop. Don't use a wire brush
or anything that might damage the rubber O-rings.
Remember that your number one priority is to get
plenty of grease on those rubber O-rings.

Resources: Tsubaki Complete Chain Guide

How to check the chain for a tight spot.

• Switch off engine, put into neutral, put bike on cetera stand.
• Using some type of gauge, measure the slack of the chain under the
  swing arm, then move the chain a small bit and measure again, you are
  looking for a difference in the chain slack.
• Use red tape to mark the points that have a tight spot and black
  tape to mark the points with a lose spot.
• Rotate the chain thru several revolutions and check that the tight/lose
  spots occur on the same part of the chain each time.
• If the tight/lose spots occurs on different locations on the chain
  each time you rotate it, then the problem may be caused by the sprockets
  or something else, although the chain may still have a tight spot.

Sometimes one link on the chain become badly worn and the other links have not

• Switch off engine, put into neutral, put bike on cetera stand.
• Tighten chain fairly hard, danger, if you take the bike off the center stand
  while the chain is this tight you will break several things.
  
• Rotate the rear wheel as if the bike was moving forward,
  watch the top of the rear sprocket, if the chain clicks or slips
  on the sprocket then that link has failed and the chain/sprockets
  need to be replaced.

Check for stiff links by spinning the chain and watching for a link that
doesn't straingten when if comes off the sprocket.

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.