fast by ferracci has this kit for around $800 if you send them your cylinders 10.8 or 12.0 compression. They could also install larger valves. Has anyone done this ? I also have a 180 55 17 on the stock rim I have no problem with it.
It does seem like an attractive option. I think they advertise a 20% increase over stock for something like 72 rear wheel hp. I wonder how much my local shop would charge to install the larger cylinders & pistons. The roads I ride on don't require boatloads of power, so any deficit my 620 has doesn't really show up. With 20% more I might be able to enjoy this bike for a long time without having to trade-up. Only problem is that I also need to upgrade the suspension & brakes. So how much money do I really want to put into a 620 instead of just buying a 1000DS or a massaged 900.