What exactly is required to use a YZ450F Carb on 426?

Hi Guys,

I am in need of a new carb for my '02 426 and from everything I read it's just best to upgrade to a 450 carb. My question is what exactly I'll need to complete the swap aside from just the carb itself.

I have searched and read a bunch of different threads but none seem to give a good detailed description. When looking at pics of the 450 carb on ebay, it doesn't look like the adapter that goes from the carb air intake to the air box on the 426 will fit it. The one on the 426 has bolts on either side. It looks like this adapter does not exist for the 450's. The 450's look to me like they just go straight into the air box boot.

If anyone could clarify this for me with pictures and/or part numbers I would highly appreciate it.

Here is what I am talking about:

426 inlet side:


450 inlet side:


450 intake boot which appears to mate directly to the carb UNLIKE the 426:


Thanks for your help!

Edited by AlexJohncock

Take the old one off and put the new one on. It's literally almost that simple. The 450 carb does in fact drop right onto the bike, but there are a couple of details. It fits the carb mount and air boot perfectly, to start with. But you will need the throttle cables for a YZ450. These will fit nicely into your throttle tube, however.

Next, you'll need the complete hot start setup from a YZ450. That's the plunger, plunger seal, plunger spring, cable, cable guide, cable nut, cable guide cover, and a suitable handlebar lever. Using a complete stock YZ450 clutch lever/perch assembly or and aftermarket lever like an ASV with the hot start lever incorporated will simplify things.

In most cases, stock 450 jetting works very well to start with.

Thanks for the clarification!

Are there any years that are significantly better than others?

'05 and later.

Great, I bought an 05 450 carb today on Ebay with the throttle cables, hot start assembly and all. Thanks for your help!

it's an 06 actually now that I check it. Does this upgrade actually help with power or just make the bike run smoother?

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