Post by JerryScript on Sept 21, 2013 0:29:54 GMT -5
I've found it difficult to find threads about installing a BBK (big bore kit) on a 50cc. Part of the difficulty is the search feature for this forum will not search for 3 letter terms like BBK. So I wanted to start this thread to document my BBK upgrade step by step. Please feel free to correct my mistakes, add what I've left out, or just tell me I'm full of it! 
Step 1: Research!!!
You cannot read enough or watch enough videos before starting. Every thread you read, and every video you watch will give you a bit more knowledge, and make you feel much more comfortable about the process (hopefully this thread will help as well).
I have asked about the differences between 80cc (usually 63cc in reality) and 100cc (usually 82cc in reality) kits, and have found that either one will give you the extra boost you want on the lower end, allowing you to take off from stop lights without all the cars behind you honking and cussing at you for slow takeoffs. The top end speed limitation is not your bore size, but your engine's RPM redline (and CVT setup), which will not be affected by a BBK alone.
The main difference between the two kits apart from their size difference is the main jet you will want to install. I purchased the 100cc Stage 3 kit from ScrappyDogScooters here in Las Vegas. The kit comes with an
main jet, but I had already read in several scooter forums that you should probably go with an 
or larger. I mentioned this to the folks at ScrappyDog's, and they not only switched the for an , they also threw in a larger pilot jet for free, just in case I needed it (great people at ScrappyDogScooters, I highly recommend them!).
Had I not researched this for a couple of weeks before purchasing, I probably would have made several trips back to ScrappyDog's to get different parts. Not a huge problem for me since I live in a city with a performance scooter parts store, but if you are ordering from the internet, you could be frustrated with re-ordering different parts. So research, research, research, ask questions in forums, use the search feature to find info already posted, and then research a bit more. Videos on YouTube are an excellent source of information, since many people forget to write certain details down, but they almost always mention these sorts of details in the videos.
Here is a pic of the parts I received in the Stage 3 Performance kit from ScrappyDogScooters. It includes the 50mm sleeve and matched piston with piston rings, wrist pin, circlips, and gaskets, a straight shot air intake, a performance fuel filter, and iridium spark plug, and 7g Koso roller weights. Everything you need for a basic BBK installation :
Here's a link to ScrappyDogScooters 50cc performance parts page, the Stage 3 kit is near the bottom:
www.scrappydogscooters.com/139QMB_50cc_Performance.html
Next up, preparing your scooter for installation.
Step 1: Research!!!
You cannot read enough or watch enough videos before starting. Every thread you read, and every video you watch will give you a bit more knowledge, and make you feel much more comfortable about the process (hopefully this thread will help as well).
I have asked about the differences between 80cc (usually 63cc in reality) and 100cc (usually 82cc in reality) kits, and have found that either one will give you the extra boost you want on the lower end, allowing you to take off from stop lights without all the cars behind you honking and cussing at you for slow takeoffs. The top end speed limitation is not your bore size, but your engine's RPM redline (and CVT setup), which will not be affected by a BBK alone.
The main difference between the two kits apart from their size difference is the main jet you will want to install. I purchased the 100cc Stage 3 kit from ScrappyDogScooters here in Las Vegas. The kit comes with an
main jet, but I had already read in several scooter forums that you should probably go with an 
or larger. I mentioned this to the folks at ScrappyDog's, and they not only switched the for an , they also threw in a larger pilot jet for free, just in case I needed it (great people at ScrappyDogScooters, I highly recommend them!).Had I not researched this for a couple of weeks before purchasing, I probably would have made several trips back to ScrappyDog's to get different parts. Not a huge problem for me since I live in a city with a performance scooter parts store, but if you are ordering from the internet, you could be frustrated with re-ordering different parts. So research, research, research, ask questions in forums, use the search feature to find info already posted, and then research a bit more. Videos on YouTube are an excellent source of information, since many people forget to write certain details down, but they almost always mention these sorts of details in the videos.
Here is a pic of the parts I received in the Stage 3 Performance kit from ScrappyDogScooters. It includes the 50mm sleeve and matched piston with piston rings, wrist pin, circlips, and gaskets, a straight shot air intake, a performance fuel filter, and iridium spark plug, and 7g Koso roller weights. Everything you need for a basic BBK installation :
Here's a link to ScrappyDogScooters 50cc performance parts page, the Stage 3 kit is near the bottom:
www.scrappydogscooters.com/139QMB_50cc_Performance.html
Next up, preparing your scooter for installation.
I guess there's no use (*