hey numroe what have you done to yours ?
Lot's of little things. eg:
Re-greased head stem and rear susp, rim locks in both wheels, tensioned spokes, trimmed long spokes to protect inner tubes, loctite everything that needs it, fresh brake fluid, adjust front brake master cyl, correct len SS bolts on swing arm and shock ends, mudflap over rear shock, diff tyres, fork service (flush out old fork oil with 5wt, then 285ml of 7.5wt motorex oil), shock re-oil and gas, 800 lbs/inch rear spring, dialed in rear sag and clickers, oko26 carb (raised float level a bit, main=K102, slow=K38, needle=1richer than mid), intake snorkle with 60mm ID dual layer unifilter (80mm OD), plastic fuel cap, 39T rear sprocket, fuelstar TM-VC in tank, neo-mag oil drain plug, alum slinger, Akunar ignition coil, heads mods: Akunar valves, springs, A1 cam. Dremel piston crown for intake valve, matched inlet ports/manifold, smooth uglies out of head ports.
To-do: Another front tyre (eg, Pirelli scorp or M401), clutch upgrades, better oil cooler maybe, tougher rocker arms, Lifan150 maybe (if cyl head is the same), firmer seat foam.
The bike rips. It can be ridden pretty fast on snotty terrain. The front tyre and the clutch (slipping under power) are the current weak points.
See also:
http://www.miniriders.com.au/forum/tech-talk/15880-most-effective-mods-lifan-140-a.html#post161017
http://www.miniriders.com.au/forum/tech-talk/15882-air-intake-snorkle-2.html#post161225
http://www.miniriders.com.au/forum/tech-talk/15882-air-intake-snorkle.html#post148241