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Toby_S

What is the OD on a head pipe for an '02 WR426

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I actually have a WR250F, but I want to put the stock muffler on a powerbomb , and the OD of the powerbomb is bigger than the ID of the stock gasket (header to muffler). I think the Mufflers are the same for 250 and 426, so if the header is the same OD I can get a 426 gasket. OD measurement of gasket would be good if you have it.

Thanks,

Toby

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I actually have a WR250F, but I want to put the stock muffler on a powerbomb , and the OD of the powerbomb is bigger than the ID of the stock gasket (header to muffler). I think the Mufflers are the same for 250 and 426, so if the header is the same OD I can get a 426 gasket. OD measurement of gasket would be good if you have it.

Thanks,

Toby

Hey Toby, your lucky day.

I just happen to have 2 of those gaskets in my box brand new and my calipers out on the bench when I read this.

Yamaha part # 3VD-14613-01 (exhaust port to header gasket) 2002 YZ426F

O.D. 46.76 mm (1.837 in.)

I.D. 36.10 mm (1.421 in.)

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I was actually looking for the ID that sleeve that goes between the header and muffler.

Thanks,

Toby

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I was actually looking for the ID that sleeve that goes between the header and muffler.

Thanks,

Toby

The ID of the sleeve you mention now would be the OD of the header pipe for a 426 which is right around 41 mm. :bonk:

That sleeve is soft so getting a proper measurement is near impossible.

I measured my stock 426 header and it is 41.33 mm at the header/mid pipe junction which is where that soft sleeve is used.

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Thanks a lot! That's the same size as my powerbomb. The mufflers are actually different, though, so I need the OD of the Gasket or the ID of the muffler. I'm hoping that the muffler ID is right around 48mm. Do you have a muffler or gasket you can measure?

Thank,

Toby

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Thanks a lot! That's the same size as my powerbomb. The mufflers are actually different, though, so I need the OD of the Gasket or the ID of the muffler. I'm hoping that the muffler ID is right around 48mm. Do you have a muffler or gasket you can measure?

Thank,

Toby

OK the OD of the gasket (sleeve) is between 48.30 and 48.55 mm, the sleeve as I mentioned is soft and you can bend it around really easily, so when they come new in the package they are not perfectly round, but I measured it in several places and came up with those measurements.

I am following this info closely because if you make this work I may get a powerbomb header to use with my set up, it seems like a good option.

I like the concept behind powerbomb.

So now I will ask you to do ME a favor,

I rarely come into the WR forum, I am mostly over on the SuperMoto forum, so if you make this work PLEASE send me a PM so I know it works and I have an option to use the powerbomb if I want to that way I wont have to come looking for this thread if it gets buried in the ether.

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I'll keep you posted. It looks good. I checked on the parts fische, and the clamp band is the same for each bike, so the OD must be the same. Your measurements are in the ballpark too.

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