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Michael Cahill

Big exhaust leak - end of header

14 posts in this topic

I've developed a rather larger exhaust leak at the end of the header pipe, where it connects to the silencer.

Bike: YZ400f

Bought the bike with white bros silencer slip on, but it looks like previous owner used a non stock header, and some sort of tape to seal the two together.

Well, the tape has now worn out, and there is nearly a half centimeter gap in the space where the two slip together.

Any suggestions on how to properly seal this?

It looks like the header and silencer are two totally difference sizes.

i've looked for some good seal tape, but haven't found anything more that a few hundredths of an inch thick.

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Thats a helluva gap to try and fill. I would suggest getting an adapter machined (turned on a lathe) to join the pipes together. A tube about 40mm long O/D so it just fits into the silencer, I/D so it just slips oner the header. A small shoulder to stop it disappearing up the silencer would be advisable. Assemble with a spot of high temp RTV.

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Yeah an adapter as mentioned would work or some type of gasket maybe like the stock one? Not sure if the gasket would work on the silencer though, pics would help. In a pinch you can get an extra piece of pipe about an inch or so long that fits between the two and then put high temp silicone on both sides to seal it up. You must clamp together though which requires slots in the end of the silencer so it will collapse a little bit. I did that for a temporary fix a while back on my ATC.

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I'll get some pics up in a bit.

how exactly should i go about getting something like that machined?

Or would it be easier just to get another header?

I dont know where the current one came from, but its deff not stock.

anone know what size the white bros E series pipe is?

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i have a few of these adapters... let me know header size to muffler size and i will see what i have... they came with a yosh system and i also got a few with my new megabomb header and once i got my fmf muffler i didnt need them anymore

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i have a few of these adapters... let me know header size to muffler size and i will see what i have... they came with a yosh system and i also got a few with my new megabomb header and once i got my fmf muffler i didnt need them anymore

Awesome :thumbsup:

just need the diameter?

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What does the leak sound like? im having problems with backfire and wondering if its a leak or varnished pilot.

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When I got my FMF slip on it specifically stated that you should use high temp sealant like RTV for the mating joint. There was very little gap and I only needed just a bit, seemed odd that it didn't come with some kind of clamp or something... The stock clamp only works with the stock silencer.

Anyways, RTV works, I've been using it for about 4 ride hours now, looks pretty good too.

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I always try to use a clamp even on the pipes that "you don't need to." If you cut slots in the front of the midpipe on the muffler, you can clamp it after you RTV it. The slots allow for compression.

So Michael after you get your adaptor, cut some slots as wide as the clamp width so you can seal it up as good as possible. Use a TBolt style clamp they work perfect.

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Please continue...

wrap the header end?

yes..just cut a 2 inch wide strip then fold it in haf so it is now 1inch wide and wrap the header until you are just at the diameter of the silencers pipe..tighten your clamp and done.

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I like the aluminum foil idea.

although i'd like to do it the right way with an adaptor.

I just dont know where to get one of these.

Nickm27: Still have thos extra adaptors?

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yes sir i do... i have 2 different sizes... let me know the I.D. of your head and same on you midpipe where they would both connect and i will see if i have the right on for you

send them to my email. nrmorris@live.com

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