[blueboy5000]

Here's the deal with BBKs;

1) You'll have THE SAME top-end, you'll just reach it faster, you WILL NOT climb hills better or faster.

2) The 139 engine is NOT stable with a 100cc BBK, it is TOO THIN in the "jug" and prone to over-heating, GREATLY reducing longevity of engine.

3) It's not an easy job to do a BBK. In fact, I have seen only two people without engine/mechanical backgrounds succeed in installing a BBK.

4) Most BBKs are very low quality. There are good kits, like the Tadia and the Malossi, but most are serious garbage.

5) A BBK is a complete waste of time without all other mods done FIRST. A BBK will not improve your bike's performance without properly tuning the engine, carb, and CVT. Therein lies the rub; as you gain a whole lot of performance with modded ANCILLARIES. I'd do the ancillaries FIRST, then determine if you want a BBK.