I spent some time digging into the "Big Bore" today. I can tell you that I can provide a complete top end " Big Bore Kit" up to a +3mm for under $500.00 usd. An initial order would take 4 - 6 weeks to get pistons manufactured.
More importantly. . . . . .
I would be more interested in a carburetion of the LC4 rather than merely increasing capacity.
I have heard of, not directly experienced yet, enormous increases in power just from being able to provide the proper mix.
Several of you have heard my little "keep it to the basics" speech before attempting to pass along technical information. Bl d'or has hit the nail on the head. The right mapping, exhaust, timing (read tuning) can make all of the difference. Simple modifications to the stock systems can result in huge increases. It can sometimes be hard to digest that the Brands/Manufacturers we love have to appease so many different concerns. Performance, reliability, governments, retail costs, etc. Many of these manufacturers try to find the perfect balance. Always at the sacrifice of performance. Almost all current new model powersports, automotive, generators, IC engine based machinery, diesels do not operate at the peak mechanical potential. They are limited electronically and mechanically (component wise) to satisfy requirements other than peak performance. The people that understand this and how to circumvent it ALWAYS make the most horsepower. These types of people have names like Jack Roush, Barry Grant, Vic Edelbrock, Petri Mäkinenerry, Paul Gast, Kevin Hunt, Tom Morgan. I have personally watched three of these guys make simplistic modifications that have produced horsepower increases of 8 - 12%. No parts swap-outs, increased (or altered) displacements or re-engineered electrical systems!
The catch is that most of us do not have either the skills, tools, or time to achieve these results so we buy big bore kits, cams, pipes, throttle bodies, tuners. Some of us (the lucky or dumb depending on perspective) even stake our careers on making a living selling, installing, advising these parts!
Sorry for the thesis dissertation! It really struck home when BolDor made the comment because it was pure GOLD.