Best bang for your buck!  By  ryaanlx (Read 1,266 times)

Just bought this one and it will be here tomorrow. A couple of others have installed it and liked it.
www.spi-parts.com/gy6-airsal-81cc-big-bore-cylinder-kit-02350150.html

Ok Scrappy is where Fawkes kit came from, not the cheapest, you can probably find this kit on ebay much cheaper...
I should mention I already had the 20mm carb, HP cam, big bore head, 100 mj, and the free flow exhaust. none of that is included in the kit.

Here's the link to the kit, look for the 100cc bbk kit, don't know why they round up like that it's actually only 83cc, I suppose it's all marketing.. The kit cost is $89..
www.scrappydogscooters.com/139QMB_50cc_Performance.html

The valves are in the Head and come with the head, In my case the 50mm Big Bore head came with bigger valves. I'm told you can use the stock head with an 50mm kit, but as I understand it's not recommended, as it will raise your compression ratio to much over the long run, better to use a matched set, 50mm bbk and 50mm head, if 52mm bbk then 52mm head. The cam is optional but for better low end torque it's required.

A 150 carb is bigger, 23mm and up I think, and not really recommended for a 139qmb, however some have made them work, but with lots of effort and understanding....

I have several sources for parts, Scrappydog, Enviormoto, Mainpeace, Tvnacman, Partsforscooters, Jetsrus.. Specifically the NCY Big bore head and HP cam, I got from Enviormoto, my muffler and 50mm kit I got from Scrappydog.. The 20mm carb from Mainpeace, my main jets are from jetsrus..

I should also mention, when you change your 139 to something like this, you throw your drive train out of balance too.. You may need heaver weights in your variator, and better tires to handle the speed and power.. When you hit this level of mods, you can pretty much throw your wallet out the window.. Cheap it is not.

Good Luck

Yes that is correct about the second base gasket . I had a TaoTao that cracked a piston and 6 weeks later it exploded . I was mad and joined the old website and was suggested the AirSal 50mm kit mentioned above . I went to my dealer and said I didnt want another kit and mentioned the Air Sal . Well it was fate as he just had gotten in two kits . It has way more power than the secret 63 . I used 5 gram rollers main jet the rest stock and it would zoom . The kit is designed to use the stock head which has a smaller combustion chamber than a 50mm head does so compression would be higher . I think MillSC tried it with a 50 or 52mm head as it would have better flow than a 40mm head with smaller valves