Good morning,
Could anyone offer advice or opinion on the which engine sprocket is most suitable for a B40 using a standard (B25) gearbox?
I have a WD B40 which currently has it's original WD gearbox.
Last year I fitted a 28T primary sprocket from a B44. This gave a much more relaxed cruising speed but made the bike struggle on hills.
I am about to strip the gearbox and fit a set of standard B25 gears but I'm wondering should I keep the 28T primary sprocket or revert back to the standard 23T.
Any advice or opinion would be appreciated.
Many thanks
Ian
Whatever gears you fit the top gear will always be the same ratio.
Hi,
When you say primary sprocket do you mean the one on the gearbox rather than the one on the crank? 5 teeth difference on either is a massive difference. If available a gearbox sprocket with two more teeth would make a good difference and not really affect hill climbing. The standard gearing takes in to account carrying a passenger and/or some luggage so solo riding should be fine.
Dave.
Hi,
Out of curiosity it is worth comparing the B40 and the B44 for power.
B40 20hp @ 7000rpm
B44 30hp @ 6500rpm
Expecting the torque to be proportionally higher for the B44 it can be seen why it can pull a higher primary gear.
Dave.
Hi Gents,
Thanks for the replies.
The sprocket I'm referring to is the duplex one on the crankshaft.
The standard for a C15 or B40 is 23T. In Rupert Ratios excellent engine book he advises fitting the larger 28T one to a WD B40 to get less revs at cruising speeds on the road. It makes longer distances more relaxing.
What I'm wondering is will this still be needed if I fit a set of road gears. As idie quite rightly points out the overall top gear ratio is still the same.
The larger 28T crank sprocket and the WD gears are hard work when hill climbing etc. but hopefully this will be better with a set of road gears??
Cheers Ian