Couple of engine questions

[Rago]

So I got to looking at this Maxfine & have determined that it is indeed a Lifan based bike going off of pics on the web. In fact, Katoranger's engine is identical down to the exhaust routing & muffler! Y'all weren't kidding about the three basic groups of Chinese bikes thing.

Anyways, I'm wondering about possible performance mods (exhaust, air filter, etc) & what's available? I noticed that motorcycle carbs are apparently sensitive to jet sizes, correct? How do I go about tuning a carburetor &/or changing jets? Sorry for the newb questions, I'm just learning still.

Here's another question, probably the most important & needs to be checked ASAP. My bike is EXTREMELY cold natured & won't fire up unless it's at least 50+ degrees outside. When I do get it started, I have to keep feathering the throttle for a few minutes in order to keep it running regardless of choke position. When it warms up, it idles at 6,000 rpm! I'm almost positive it shouldn't idle this high or be this hard to start. Does anyone have any suggestions as to what I should do? It isn't fun kick starting my bike 4 or more times every time I want to ride, lol (electric starter isn't working).

[Wild_Alaskan]

there is a little fuel screw on the carb near the intake manifold, try screwing it out 2 turns, you can also raise the needle a notch or two (search this).

for jetting you take off the carb and the carbs float bowl, and swap the jet in the center (flathead) I recommend a 115 for the gy-5 with exhaust and air filter mods. The idle jet could use a couple sizes larger IMO also although i have not tried that

[Q]

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[Rago]

Originally Posted by Q

I don't know about your particular bike but the Lifan GY5s have a defective choke cable clamp design that prevents the choke plate from closing all the way.

Q

So this would cause the hard starting, high idle, or both?

Wild_Alaskan, thanks for the input. I'm going to try messing with the fuel screw to see if that helps. Screwing it out would mean turning it counter-clockwise correct?