..K & N air filter

[zombie]

The gy6 is pretty much a dead ringer for the kymco 4t set up! Having those guide lines posted will most certainly help, if people can find the post. The trouble I see most often is in people finding advice  such as yours, and shopping the "clone" sites. Thats where the problems begin for most. The fella I bought my  zx/super fever from is a very talented scooter enthusiast so I had a jump start on which parts to buy. Just had to shop around for price! It sounds to me like you (Dr.Moto) have some talent as well. While I DO NOT want to attempt to speak for anyone, I believe your experience, and parts knowledge can benefit allot of people looking for help here. At the moment my scoot is pretty well set up, but I am looking around for a project super 9 to set up in a more "full race" fashion. Anyone that sets up a "drag" scoot is someone I will be looking to for advice/ opinions. Sorry for the Hi-jack... PLEEEEAAASSE stick around!

[Shaka]

Much agreed, definitely an asset!  We could use more of those around here!  Any advice on final reduction gears and/or reed valves would be appreciated!  Check out my thread under zx50.  Please stick around!

[Dr. Moto]

Not a problem 

[wordslinger]

Most of my experience is with the Chinese GY6 and Im assuming these Kymco setups are a bit different.

Setups I use for the Chinese 50cc GY6

50cc GY6 Free Flow Airfilter 88 main (I think this setup runs just a tad rich)
50cc GY6 Free Flow Airfilter & Exhaust 90 main
72cc GY6 and Free Flow Airfilter 88 main
72cc GY6, Free Flow Airfilter, and Exhaust 95 main

I have never had to tune past a 95 main jet except on my drag race scooter, its running a 102 main. It has 85cc, velocity stack, port & polished performance head, cam, exhaust, 19mm carburetor, lightened rocker arms, lightened valves, ect. Never have had it on the track yet but I can tell you its as fast as a stock 150cc off the line and would hang up to about a 1/8 mile then I run out of gear.

...this is all very interesting to me...as I have a 105 (1.05mm) main jet in my A50..with a free-flow filter..stock exhaust...and find that it seems to be lean in cold weather..less than 40 degrees F...hmmm....

[zombie]

They will ALL run leaner in colder "denser" air. Those bordering on the rich side (in warm conditions) will tend to run better than those on the lean side. All the jet sizes are relative to the manufacturer anyway. Mine gets pretty "snappy" on the colder mornings. More like a cracking whip than a purring tiger!

[Dr. Moto]

These settings are on the Chinese carburetors so it may be different. However I use a 115 main jet on a 150cc scooter with a free flow airfilter and exhaust for reference.