my drivetrain works perfectly. i've had 2 different engines so i should know how the spec. power feels, and its good
(real top speed of 172km/107mile per hour where the normal indicator says almost 200km/h)
1st engine had 8.000 miles before one of the big-end bearings decided to stop working and my 2nd engine has about 31.000 miles
i did raise the rear end (45mm) so that would make wheelies from pure power harder. but before i did that it, it also never made power wheelies when driving alone.
guess i'm to heavy
75kg/165lbs
a fresh chain will have less friction, so it will have more power at the back wheel, however the difference depends on the state of the old chain and in most cases you wont notice any difference in power
a good chain will transfer 92-98% of the power, but it is possible for an old chain to only transfer 80%
but thats offtopic
i own my b4 since nov 2003