Originally Posted by Chaz
Don't know how you would police that! as the cranks are balanced from the factory to a certain degree, I've not done anything below the barrels on my bikes but if I did I would certainly balance the crank! it would be daft to go to the expense of a rebuild without.
And there in lies the problem
Policing it. A standard factory crank may or may not be distinguishable from a balanced or modified crank, I may have to investigate futher to see just how distinguishable they are
It would be hard to tell a balanced crank from a slightly lightened one without stripping the crank from the engine and removing the rods etc and then weighing to see how it compares to a crank that hasn't been modified in anyway after leaving the factory and allowaning a small tolerance
Now if its easy to tell a unmodified crank from a modified one be it balanced or lightened, possibly by just removing the front cylinder and rotating the crank, policing it becomes easy
Unmodified = legal
modified = illegal
which makes the rule as it exists suitable for the series
If this rule has to be modified to allow for grinding, drilling or welding then it becomes very unclear where balancing a crankshaft then becomes a performance advantage by removing a little extra.
To date DD bikes have proved fairly reliable with very few blow ups and little debris being left on the track for others to hit.
So if the rule can't be policed then it becomes meaningless and may as well be dropped which then leaves the way open to those that want to push the limits of crankshaft reliability vs weight.
Is it a gray area or is no Mods Clear enough
personally I don't see the need to modify the crankshaft on a DD bike as they do come with a certain degree of balancing from the factory and like the rule in its current state, as it should make the series easier to police.
I have owned bikes even back in the 80's such as my CB900F taken out to 1065, Carillo rods, Drysump, lightened, balanced and knife-edged crank so do know why its done and the benifits to be gained against the reliability factor.
But I certainly don't want to see DD heading down this route.