It might take 46 years but eventually our beloved 1970s two-stroke trials bikes reach the point where they have part-burned enough fuel to clog up the exhaust system with carbon and gunk.
Recently our own tat ty's

TY reached that point and the exhaust gunk was cleaned out using a time-honoured method.
I'm told that the cooking was managed by waiting until the fire was down to a dull roar before putting the exhaust in and a chain was attached to enable retrieval when it was considered to be cooked to perfection.
Preparing the oven:

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The cooking phase:

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Some of the cooked internal detritus:

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Close-up of detritus:

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Afterwards the exhaust was a lot lighter and enjoyed much better breathing