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expansion chamber seal/gasket?

  • lolipop50
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expansion chamber seal/gasket? was created by lolipop50

I've recently been doing some service/maintenance items on my 1971 DT-1MX, which I have owned since new and rode the heck out of it weekends during the 70s-80s. Lately I've just been keeping fresh fuel in it to start occasionally and take a few laps around the backyard. I am wanting to re-new the seal or gasket where the expansion chamber connects to the cylinder. Pulled the diamond shaped metal retaining donut off and discovered a series of metal bands along with some prehistoric packing of some kind. I can't seem to find a decent diagram of how this is supposed to go together; can anyone shed any light on this? My first post by the way, thanks in advance for any help.
26 Oct 2021 14:58 #1

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Replied by msavitt on topic expansion chamber seal/gasket?

 dWelcome to a great group

i have a 71 dt1e and just checked partzilla and determined that the exhaust connects up to the cylinder with what appears to be the same parts.  The prehistoric stuff is the attached pic, not sure what it is made of but felt like graphite / mica impregnated fiber perhaps fiberglass. 
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26 Oct 2021 18:02 #2

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Replied by MarkT on topic expansion chamber seal/gasket?

I think what you are describing is the "donut" gasket that goes into the recess in the cylinder under the two-bolt flange.

Yours came apart...  just remove the debris and get a new one from Yamaha or a parts place.  The new one will be a one piece ring. 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
26 Oct 2021 19:36 #3

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Replied by RT325 on topic expansion chamber seal/gasket?

This is what you want between flange & cylinder. Second link is what you need to pack in the area the pipe fits into. I just welded my pipe into the flange. It's rubber mounted in a couple or 3 places so never a problem,--except more difficult undoing bolts or allen screws at the flange.
www.partzilla.com/product/yamaha/214-14613-09-00

www.partzilla.com/product/yamaha/248-14623-10-00
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Last edit: 26 Oct 2021 21:08 by RT325.
26 Oct 2021 21:05 #4

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Replied by lolipop50 on topic expansion chamber seal/gasket?

Thanks for all the great info. Now that I see what the gasket looks like new it makes perfect sense. Mine had come apart and I was looking at a series of metal bands not held together, and the rope packing goes into the recess that the exhaust pipe fits into. Just waiting on the parts to put it back together; thanks to all who replied!
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27 Oct 2021 09:04 #5

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Replied by Gr8uncleal on topic expansion chamber seal/gasket?

Though it's not immediately obvious, that "donut" could well be a two piece item (it is on the non MX DT and RTs).

Sit the donut flat side down with a couple of bits of wood or such like supporting it by the two mounting holes. The inner ring should be sitting slightly proud - bang this with a wooden mallet a few times and it should come out - it is only a press fit. You can then give both surfaces a thorough clean and then re-assemble.
27 Oct 2021 10:43 #6

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Replied by MarkT on topic expansion chamber seal/gasket?

Donut I was referring to (gasket, seal, whatever you want to call it) under the flange is one piece.  

Two bolt steel flange is two pieces with an inner sleeve that some of you have figured out how to remove and replace.  

(I've never tried to disassemble a flange...  I'd probably destroy it 

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
27 Oct 2021 12:31 #7

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Replied by Gr8uncleal on topic expansion chamber seal/gasket?

"I've never tried to disassemble a flange...  I'd probably destroy it."

Been there, destroyed that, Mark! 

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 That's why my first hitting implement is now a wooden hammer. 

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27 Oct 2021 13:16 #8

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