YZ250F exhaust on -08 YZ450F


What I have now is a brand new US spec YZ450F -08 with the crappy silencer. I also have a YZ250F -07 that I have put an FMF 4.1 silencer on.

I was thinking was getting another 4.1 for the 450, but then I got a crazy idea. Since the 4.1 part number for the 250 and the 450 is the same, I assume the silencer from the 250 would fit(physically) on the 450 no problem. Now that I think about it the bikes might have different size headers since the silencer came with two different collars.

I'm not assuming anybody to have experience about this, but do you have any clue whether this would be a waste of my time or worthwhile?

Edit: Just to clarify, what I meant is trying the stock 250 exhaust on the 450. The FMF would obviously work but I do not want to switch back and forth since I still intend to ride the 250 as well.

just try to put it on, it will only take a couple min.. but now that i think about it it might not fit with the size of the header, but you never know..

If you mean the OEM muffler from a YZ250F, no, it won't fit. Different header sizes.

The FMF muffler fits over because it is separated from the mid pipe.

The YZ250F and YZ450F had the same diameter header in 06. For 07-08 Yamaha made the header larger on the 450. FMF sells the same pipe for both bikes, but it comes with a spacer sleeve that fits on the 250F header and uses that as the "step" in the pipe instead of building a step in the pipe right behind the midpipe junction as they did in the past. For the 450 the sleeve is not used.

Thanks guys, I just ordered an FMF 4.1 silencer for the 450 as well.

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