139QMB GY6 Big Block

ScooterDan · 05-19-2016, 09:18 PM

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!

bull · 05-24-2016, 08:12 AM

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

05-24-2016, 08:12 AM	#2
bull Join Date: Feb 2015 Posts: 257	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
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