Here is a link to a LA Times review of the JH600.  Not all bad. 

http://www.latimes.com/classified/automotive/highway1/la-hy-throttle28nov28,0,7440487.story

Can any of you discuss your experiences with making the air filter/rejet modification?

I will be making this change as soon as the parts arrive.

If you intend to do any off road riding I'd be leery of  removing the air box for fear of getting the filter water soaked during stream crossings or  dust clogged during other conditions.  The filter on the LF200gy-5  looks to me just like the filter on an old xr200 and plenty good.   I think it is different than the setup on the gyIII.  The issue addressed by the air filter/bigger main jet mod is to get more fuel going through the carb which requires a commensurate increase in air flow which removing the airbox accomplishes.  I'm thinking that drilling a bunch of 1/2" holes across the top of the air box and letting the carb draw additional air from under the seat may be a better option than completely removing the air box for the enduro model lifan.  In that event, you can save the $$ on the new filter and use the plenty good one already there.  Just an idea.

There are those that think that the Chinese government has allowed their people to travel to far down the road of capitalism that there is no turning back.  Maybe I'm just too old but Tiananemen square doesn't seem so long ago.   The rule law is not deeply enough rooted in that country for me to invest more than a flyspeck of my meager pile of assets there.  On the other hand I sure do like their manufacturer's motorcycles at the price they sell them for.  If I'm wrong, and I usually am, It won't be the first golden investment opportunity I miss. 

I messed up and posted the last message before I was finished.  Countrycruiser seems to have an axe to grind against any Lifan 200 not sold by American Lifan.  The  TMS200 motorcycles sold by T-Motorsports are manufactured by Lifan China at the very same plant as the ones sold by American LIfan.  For the most part they are the same bike but some have a counter balanced cam shaft and some don't.  Stryder's reliance on the Thumpertalk post  is misplaced .  From the Lifan china web here are two links to the common 163fml-2 engines currently placed on most Lifan 200cc motorcycles.

http://www.lifan.com/en//product_list.asp?parentid=8608&id=887

http://www.lifan.com/en//product_list.asp?parentid=8612&id=887

Both are pushrod and not OHC  engines. Lifan does make a 163fml-Z2 OHC version but I am not aware of which motorcycle it is on.  Gray market products are not to be confused with counterfeit products.  Gray market products are genuine products that are distributed outside the normal distribution channels.  It appears that Lifan China, as Almonpoole has correctly stated, hasn't settled on a clear vision of how it wants its products distributed in America.  American Lifan sells products with the words  "Lifan" painted on them.  TMS, Rabbit and others  and other sell nearly identical products, manufactured at the same Lifan factory with different words printed on them such as TMS200.   As such, it appears to me that the TMS200 sold by T-motorsports is not a gray market Lifan motorcycle but motorcycle produced by Lifan for sale in the US without the Lifan brand name on it.  All of the stickers and documents accompanying  my TMS200 show it to be produced by Lifan.  My research has convinced me that it is 98% identical to the American Lifan sold 200gy-5.  If you need to have the services of a dealership to prepare and service your Lifan manufactured motorbike you probably should stick with an American Lifan dealer and pay the commensurate higher price.