Replacing the Front Sprocket (16 to 17 tooth)

(Please note this article needs pics - if anyone can supply then let us know)

Time required:   About ½ an hour ( a bit longer for the first time)

Tools:

• 6mm Allen key
• 8mm (preferably ¼ inch or 3/8 inch), 14mm, 22mm and 27mm sockets
• 2 x 14mm open enders
• Torque wrench is handy but not essential.
• Rags, light grease and a spray can of brake cleaning fluid for cleaning.
• Tin of Halfrods liquid grease with a ‘straw’.

 
Torques:

• Rear axle bolt - 78 lb/ft (front axle bolt is only 44 lb/ft by the way)
• Sprocket bolt – 40 lb/ft

     
Sequence:

Put bike on the centre stand or rear paddock stand if non ABS model (Paddock stand makes life much easier but it is not essential).

Loosen the axel bolt/nut – 22mm and 27mm sockets.

Undo the locking nuts on each of the chain adjusters - 14mm.  Wind out the adjusting nut about 60 flats or 20 x 180 degree turns.  Adjust each side equally to help retain your wheel alignment when you come to reassemble.  Push in the wheel.

Part remove the gear change linkage. You only need to remove the two lower pivot bolts – 6mm Allen key.  Leave the top gearshift arm and pinch bolt alone, you do not need to remove this.  With the two lower linkages removed the link mechanism can be lifted up and tucked out of the way into the chain guard.

Remove the 3 x 8mm bolts holding on the clutch slave cylinder, leave all the hydraulic pipes attached.  Pull off the slave cylinder, it may be a little stiff as it is held on with two locating pins and a central clutch rod.  Carefully lift the slave cylinder off and tuck to the left out of the way.  Do NOT pull in the clutch lever - no fluid should either be evident or will leak out but you do need to treat gently as twisting of the brake fluid pipes will lead the slave cylinder piston to be pushed out just a little bit – you will notice this on reassembly.  Make sure the two locating pins are left in the block and withdraw the central clutch rod.

Remove the 2 x 8mm bolts holding the chain sprocket cover (one top and one at the bottom of the cover) and wiggle (technical term !) the cover off to expose the front sprocket with chain.  There is a guide plate behind the cover which is located by two locating pins, take it off to clean if you wish otherwise leave in situ.

Remove the 14mm Sprocket retaining bolt and washer.  This bolt should only have been torqued to 40 lb/ft which is not all that much and should reasonably easily come undone.  The simplest way to do this is to lean over the seat with foot on rear brake pedal – keep wife away from Biffer.  Gives easy access to the sprocket nut from above and a decent socket with no extension bar will do the trick – even easier if you have the leverage of a torque wrench.  An open ended spanner on this bolt will be difficult, get the right tool before you start.

The sprocket will now pull off.  If it has rusted on the spines give the centre of the sprocket (metal part) a light tap with a hammer.  If really bad use a release oil like Plus Gas.   Check the condition of the big oil seal behind the sprocket.

Clean any gunge around the area.

HALF WAY THERE.

Offer the new sprocket up to the chain (have the sprocket details facing you) and slip over the splines having first applied a thin coating of grease to the splines.   It will be harder to fit the 17 tooth sprocket over the splines than it was to remove the 16 toother as the chain will be tighter.  If needed loosen the chain adjusters by another 10 or 20 flats (same each side).  The fact that a Renthal or a AFAM sprocket does not have the bonded rubber covering on the sides of the sprocket like the Honda OEM part IMO makes no difference at all - the rubber is supposed to act as a shock obsorber of some sort  and quieten its operation.

Replace sprocket bolt and washer and tighten.  Gut over seat routine with foot on brake pedal.  If you do not have a torque wrench then a standard socket with a 10/12 inch handle is fine, just do it up good and tight but not excessively so.

Tighten the chain adjusters being careful to adjust equally each side remembering that because of the extra tooth the chain will not need tightening as much as it was loosened.   Temporarily adjust chain to c.25mm up/down play in centre of lower chain.

Replace the guide plate and 2 x locating pins (assuming you remover in the first place), clean the worst of the muck from the sprocket cover - a Rolls Royce job is not needed because as soon as you re-grease the chain the cover will rapidly fill with fling anyway -  just make sure any mating/jointing faces are clean and refit with the two 8mm bolts.

Lightly grease the central clutch rod and replace.  Replace the clutch slave cylinder housing – remember the two locating dowels.  You will notice that the piston will have pushed out a little, no worries, offer it up to the back plate and finger tighten each of the three bolts (bottom is the small bolt).  Tighten the bolts a turn each gradually and evenly pushing the piston back in place until the slave cylinder is tight against its back plate, final tighten and you are done.

Before you refit the gear change linkage use the halfrods (or similar) liquid grease, insert the straw under the rubber boots of each of the four links and squirt grease in (you will be amazed just how smooth the gear linkage feels when you ride the bike), grease the two pivot bolts and refit completing the replacement of the gear linkage.

Spin wheel and make sure everything seems OK, nothing clicks or catches within the sprocket cover.   Look at the rear wheel rim whilst spinning the wheel to see if the rim still appears even as the wheel rotates.  It should be fine if you have counted the turns of the chain adjusting nuts but if not then the wheel needs realigning or at the very least the adjusters evening one side to the other.

Bike onto side stand for final adjustment of the chain – c.25mm is good for play and the bottom chain should be nice and clear of its slide on the swing arm when pushed hard up. Tighten the lock nuts and tighten the rear axel bolt.   A torque of 78 lb/ft is akin to using a 1ft bar on the socket and making it very tight.  You will notice with a much longer torque wrench it only seems so so tight.  Do not exceed the torque setting if using a torque wrench or you will have great difficulty in undoing the axel bolt with the supplied tool kit tools.

NB.  When tightening the chain adjuster locking nut it is not sufficient to simply tighten the second nut onto the first as if it was the second knot in a piece of string.  Lock nuts and threads do not work that way.  You need two 14mm spanners, hold the inner nut fast with one spanner, tighten the lock nut into the first nut then (the real deal now) marginally loosten off the first nut whilst tightening the lock nut into the first nut at the same time.  The lock nut works by jamming the two nuts up against the leading and following edges of the threads on the bolt, that's how they stay together and do not come off the bolt.

Spray off all the grease and sh1t (another technical term) from around where you were working with the spray brake cleaner, it does a far better job than an oily rag.

Re-grease the chain and (clean your tools) and

....go for a test ride.. – WRONG ! – ... get a cup of tea and check the whole process in you mind to make sure everything has been done/tightened/adjusted etc then....

... go for a test ride and get a feel for the new characteristics of the bike.

DONE

Andy