McCulloch MT305 strimmer muffler cleaning

[Roger Norton]

Hi All,

I'm running through the parts I need to clean or replace to solve a "won't run except at half-choke" problem with my McCulloch MT305 strimmer (2-stroke). The manual suggests cleaning the spark arrestor screen on the exhaust (muffler), but the muffler is a sealed assembly with no access plate to allow the user to remove the spark arrester screen. There is no access plate shown on the parts diagram. There is a tubular wire mesh screen inside exhaust tube, but no obvious non-destructive means of access. There is also some kind of screen inside the entry port that connects the muffler to the cylinder (see photos). Any suggestions (other than "buy a better make")?

Parts diagram attached. Photos of the muffler are below (

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• Roger Norton
• 1 Jul 2015

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• 1 Jul 2015

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). The muffler is surprisingly heavy for an empty metal box, so there may be a catalytic converter or such-like inside.

Roger.

 

[Burnerman]

Hi Roger
As you see, these cant be dismantled so the best way to clean them is to heat them up red hot with a blow torch......this will produce clouds of blue smoke but once this has gone the carbon will start to come away - more successfully if you tap the thing onto a bench.
Hold the unit with mole grips or similar.
Its also important to have a look at the exhaust port now.....make sure all carbon is lightly scraped away (piston up) to see there's no blockage.
Try running the machine with the exhaust off if you like - it will be as noisy as hell but rules out an exhaust problem or otherwise.
John