I received my rebuild kit for my 40 IDF today. The kit included a new needle and seat.
Thing is, is that my old needle and seat and the new one are totally different designs. The new on is an actual needle and seat, and my old one just has a large ball bearing that stops/ allows fuel flow. The new one has only 2 holes that allow fuel to pas through, and my old on has 5 or 6. The new one threads in and works, but Im curious, maybe somebody used the old one, cause it was better for my application. there's nothing wrong with the old one.

The new one is a 175, but my old one has nothing on it.

Also, is my float properly set if - I blow into the fuel inlet, air passes through, untill I lift the float up and it closes the need and seat when it is lifted all the way cutting off the air flow.

 

leave your current needle valve in, as its an upgraded unit called a grose jet.. the 175 that came in the rebuild kit is waaayyyy too small... i dont work on idf carbs much, but i can tell you that there are alot of crap rebuild kits for these carbs, unlike the dco carbs so make sure yours is a spain or italian kit.. i just rebuilt a idf carb for a fellow forum member, lets just say i had to buy 2 kits before i was satisfied with the quality of the carb rebuild parts

 

The rebuild kit I bought is from REDLINE WEBER.

Thanks for the info, looks like Ill be putting the "grose jet" back in.

 

Here's a comparison between the two.

 

I agree with Rob. Keep the grose jet or else that 175 needle/seat will make your engine starve for gas.