I decided to gear the bike up for a lazier ride. So I got a 19 tooth gearbox drive sprocket, one tooth larger than standard, and a 42 tooth driven sprocket.
It is impossible to torque up the gearbox sprocket nut to the required torque of 132NM without being able to stop the sprocket from rotating. I have found the best way to do this is to put the gearbox into first gear and to hold the rear brake on. That way, the gearbox sprocket is held still by a combination of engine compression and brake pressure. So it was time to fit the rear wheel. |
| Mushroom type spacer on right of wheel. The wide end butts up against the rear brake bracket |
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| Rear wheel spindle, spacer, rear brake bracket, bush and wire retaining clips |
The rear wheel, fitted with sprocket carrier and small, left-hand spacer, has the chain looped over its sprocket pushed well forward to maximise chain slack. The eccentric chain adjusters should also be turned so they are aligned to the same marks on the swingarm and pushed slightly outwards from the centre of the bike before being nipped up with an Allen key. This makes the gap for the rear wheel as wide as possible to help you get the axle through. It's easier to see what's happening this way.
The rear wheel spindle needs to be fitted from the left because it is isn't easy to manoeuvre the wheel into place, and the sprocket carrier side is the heavier of the two. I put a wooden block under the wheel to help support the weight. |
| Greasing the large aluminium bush for the centre of the rear brake bracket |
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| Axle right through, bolt being wound home. The gap between eccentric adjuster and brake bracket is visible here. |
The right-hand bolt is wound in with at 12mm Allen key, pulling the swingarm legs together against the spacers. I nipped up the axle bolts at this point before slackening off the eccentrics to adjust the chain tension, and to allow them to move inwards to their correct position.
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| 132NM of torque for the gearbox sprocket |
I refitted and bled up the rear brake and then was ready to torque up the gearbox sprocket.
It worked a charm but needed a steady hand and my largest socket (36mm). That just leaves the flattening of a tab on the gearbox lock washer - that done, job's a good un.
2 comments:
That is looking pretty spectacular that is. Should the hugger have gone in first though! ;-)
Have you geared up your 900 much? I think I'd find anything higher than standard on the 12 quite a pain when trickling in/through traffic.
Thanks - you're right :->
There's no hugger on mine. A previous owner put a Daytona hugger on yours, probably purchased with the wheels and brakes. I might get one later but am happy to work with what's there for now (albeit in highly cleaned up fashion).
I put a 19 tooth front sprocket on the 900 but left the rear as was (can't remember how many teeth it has). I don't see much traffic on my way to work though I think you are right - it would mean a lot of clutch slipping if traffic was going at walking pace or slower. 17 teeth are standard on the front and I found I was always reaching for a 7th gear with it. I thought I'd get better fuel consumption with lower revs in top for cruising along. I get a consistent 54mpg now, probably 10% better than previously. It is overgeared like this really but it suits me OK. I might go for 18 teeth next time. It's nice to have options.
cheers
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