139QMB GY6 Big Block
 

I live in Dominica ( not Dominican Republic) for the next year and a half. Anyways, it's all mountains and steep hills here. For this reason i'm considering upgrading to a big block. The kid part of me is saying go for the 100cc big block kit because it will provide a bit more speed and fun. However the adult side is thinking whether a 100cc BBK would prove to be reliable enough. Help me out here and let me know what the reliability issues are with going with a 100cc big block vs a 80cc big block. With either kit, i'm going to get the head along with it.

Thanks guys!

fix known problems first, pull all normal maintenance, perform all your tuning, then install a BBK if needed.

BBKs come in 4 sizes:

63cc - many of these are found from factory installations when they are supposed to be 49cc

72cc, termed a BBK 80 -- from my research that is what these scooters were originally designed to be by Honda- I installed only a few of these, the best one was from valley scooters-

82cc, termed a BBK 100 - these require no crankcase boring- they are generally reliable - but there are differences between China and Taiwan made

the last does require crankcase boring, as well as a crank swap. I have not personally done one of these, but my attitude here is IF you need this amount of power, just get a bigger scooter which would prove more reliable.

49cc, 63cc,and 72cc typically do not require carb rejetting- the 82cc does require carb tuning