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leaky pipe flange, what brand of sealant?

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I have an '02 KTM300EXC. Is there a particular brand name of high temp sealant to use to seal up the exhaust flange? I had some brand, can't remember what, sealed it, let is set for quite a while and it leaked after 1st ride. Also, which color, if that matters.

Little Jeff

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I think color will be your preference as long as it is in fact "high temp" RTV you use. I used the standard type you get at any auto parts store but there may be something better. Usually the quality of the seal will be how clean the parts are prior to sealing. Of course, if your pipe took a solid hit on the first ride out, that could break the seal no matter what type of sealant you use.

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Use over sized O Rings from McMaster, all the sealant in the world wont seal it.

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There is a slot machined into the flange for an o-ring. I even got a orange o-ring that came in my top end gasket kit that would fit the slot in the flange. I will try that with sealant when i fix it. The bike sat for almost 2 weeks before it was started. New pipe also. Cleaned the flange really well with a scotchbrite pad and carb cleaner, same with pipe.

Little Jeff

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I stand corrected.

I did some checking and my 01,(that has no o ring) should have one as well. Just ordered them.

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I 2nd the McMaster O rings. You won't need sealant then if your flange is not wallered out. LOL

Edited by gmoss

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the 03 and earlier 300's use a completely different interface than the 04+. On the 02 the end of the pipe is kinda bell-shaped and it just slides over, or up against the flange. I never saw or heard of an o-ring on mine. I just got used to it dribbling a little bit. I could use a crapload of high-temp silicone and get it sealed pretty well for a few rides, but then i'd hit some rocks and knock it loose again.

There is a slot machined into the flange for an o-ring. I even got a orange o-ring that came in my top end gasket kit that would fit the slot in the flange.

i'd like to see a pic of the oring from the top end kit, installed on the pipe. I searched a bit for something like that back in 2003-2004 timeframe, with no lu ck.

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