part in carby+porting

[V8_mate]

i got a ducar 125 today and i was having a look inside the carby when a part fell out. it looks sort of like a W.
is it important?
second thing is the intake slide valve meant to be difficult to open? it seems like the spring is too hard.
last question, the carby and manifold both look like they have lots of extra metal in them. would slightly porting either give any gains?
here's what the part looks like:

 

[Mack]

That part goes under the spring inside the slide. It holds the needle down. It also sounds like you have the slide inserted 180 degrees back to front which is making it bind.
The manifold should be cleaned up and matched to the head and carb. As for boring the carb, it is a good mod but you would need a little experience to achieve a good result. The shape is important and you will need to properly jet it afterwards.

 

[V8_mate]

cheers.
when i got it the slide was already around the wrong way and wouldn't go down at all. now it goes down the whole way but is really hard to pull. it might be ebcause it isn't hooked up to anything and i'm just doing it by hand though.
i think i'll leave the carb alone then. i tried porting once with a pocket bike carby and after it the bike would hardly idle and the motor died