I was recently given a 1985 Madami Defiant by a friend who was at his wit's end.  (I'm assuming the Madami is a grey-market version of the Lifan LF250 -- can anyone confirm that?)  It's titled and licensed as a Madami but I can't find any information about Madami so I'm using the Lifan LF250 manual and everything seems exactly the same. 

Anyway, the problem was that the bike would idle fine, but would not rev up.  My friend bought it new via the internet and he stated it NEVER ran right, straight out of the box.  He put 300 KM on it, gave up and parked it for 2 years.  I got it and the first thing I did was pull the fuel system apart.  I found a LOT of sediment in the tank, fuel pump, carb and and petcock.  And one of the fuel lines was plugged as well.  I'm not sure if it came from the factory like this, or if the sediment was the result of sitting for so long.  I"m inclined to think it came dirty from the factory since my friend said it NEVER ran right.

Anyway, after the whole fuel system was all cleaned out it still wouldn't run right, and by trial and error, my mechanic friend found it was sucking WAY too much air.  Part of the problem seems to be the design of the air intake -- it's like a 4" opening in the frame which just sucks air like cray.  We tried a bunch of fixes, and ended up buying a large rubber plug (bought it at Ace Hardware!), putting it in the intake hole, and drilling more and more holes until it finally ran perfectly. 

So my question is, how could this come from the factory with this condition???  There is no way it would ever run right without this kind of air restricter.  Or was mine missing one that SHOULD have been in there?  Anyone else have experience with these symptoms?

Catrinus in Portland, Oregon