[skidlids]

Yet you can buy a standard 583cc engine from a breakers for £250 stick new belts on it, give it a oil and filter change Put it in a chassis and then stick it on the podium.

So why spend so much money on all these engine rebuilds, new pistons etc.
I've see engine bills from £900 to £1350 for rebuilds without any crankshaft balancing and if you really think the balancing is going to improve your results, I doubt it.
Where as a bit of lightening for quicker acceleration (still the same bhp and weight, bit like fitting a lightweight flywheel) may help with the results as that would be cheating and I along with others would rather not have cheating going on in DD.

Now if the easy way to police it is to ban Cranksharft modifications of any sort then I'm all for it and thats how the rules have been for the last 4 seasons.
Currently modifying the crankshaft in any way is breaking the rules, is that rule not Clear enough.

Saying it is better for the bike to have the crank balanced isn't much different from saying its better for the bike to run Ohlins forks, Mag wheels or Diablo Corsas and just ignore the rules so long as it meets the BHP and weight limits.
Or is it the risk of getting caught out that determines what rules people follow and which they choose to ignore.

Here is a bit from the Sigma Performance website, they are on about the 944cc Monster but I bet the same applies to the 600

" it would be nice to rebalance the crankshaft to make sure the engine is smooth…….experience has taught us however that the 900 twin is quite resilient in terms of crankshaft balance (an alternative explanation is that its not very sophisticated engine as standard and a mere 75gram change in piston weight isn't going to make a big difference!!)."