Carburetor intake hose and adapter

I’m currently adapting a carb that has a larger OD than the ID of the cold air intake boot and there’s a slight gap between the boot and the carb. I’ve been trying to find intake hose and a stepped aluminum fitting to custom make something, but I just can’t find anything online. I’ve found premade stuff but it’s the wrong size. I’m fairly certain I’m looking up the wrong things.

This is what I’m trying to make:

I’ve found that the hose is called “intake hose” online. I just need the smooth type in 63mm.

I haven’t been able to find that aluminum piece. I need it in 56mm.

If anyone can point me in the right direction for finding these materials, let me know.

Consider PVC from a plumbing shop. Various thicknesses, various inside and outside diameters, can be painted to match your projects.
For my one curiosity, what is the vehicle and engine you are working on that uses a carburetor?

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This is an easy part to make is you have a small lathe. Maybe you know someone who owns one?

That’s true. I’ll look into that.

As for what this is, it’s actually a dirt bike. It’s a Honda XR400R. I thought this would be a safe bet for intel for this even though it isn’t a car lol


The metal adapter I would fabricate or find a 2 1/2" step down to 2" and use a pipe spreader on it to get to final dimension. A muffler shop might be convinced to use their spreader on it…

Should have continued looking, same place has reducers as well:

You can get a “Fernco” 2 1/2" to 2" adapter at a plumbing supply house.

56 mm is just a smidge larger but that’s something you could start with and spread to the final dimension or opt for the flexible reducer option above…

How about hose reducers from…where else…Amazon

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I home-brewed my truck’s air intake path using some clothes dryer vent piping. Inelegant, but functional.

You can go to rocker hardware and look at all the vacuum hose adapters. There are quite a variety. It’s also fairly easy to heat up a pvc fitting to expand it to fit. I’ve got a variety to fit various shop vacs and equipment.

Where does this adapter go? Between the carb and the head? It’ll need to be pretty strong.

From the carb to the air box

2004 was the last year for the XR400 so there might not be many after market parts for it . It was a very good trail machine . What are you trying to accomplish? Would different jets and a good air cleaner be a better choice ?