Author Topic: makita 6421 muffler mod  (Read 626 times)

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Offline mdavlee .

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Re: makita 6421 muffler mod
« Reply #10 on: September 14, 2014, 11:21:56 am »
I didn't touch the original opening. I just made a new one in the front to get the exhaust out faster.

Offline aclarke

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Re: makita 6421 muffler mod
« Reply #11 on: September 14, 2014, 11:29:35 am »
Looks and welds like aluminized steel.   I opened my last 7900 muffler exit to approx 75% larger Area. 

Offline mdavlee .

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Re: makita 6421 muffler mod
« Reply #12 on: September 14, 2014, 11:39:20 am »
It's magnetic. I didn't do any welding on this one. Just crimped it back.

Offline aclarke

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Re: makita 6421 muffler mod
« Reply #13 on: September 14, 2014, 11:54:30 am »
Probably better to unfold/crimp.  One I just did recently was a mess Tig welding even after cleaning off the aluminum coating carefully

Offline mdavlee .

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Re: makita 6421 muffler mod
« Reply #14 on: September 14, 2014, 11:55:38 am »
I figured it would be so I just tried to not damage the crimp.

Offline pigpen60

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Re: makita 6421 muffler mod
« Reply #15 on: September 14, 2014, 12:15:15 pm »
I peeled the crimp. didn't think about aluminized steel. so is there a standard exit hole ratio or such? the cat in mine looked like a kid did it, no offence to kids that can weld. my thought was to make the in and out the same size but my lack of knowledge on 2 strokes and cash is holding me back.

Offline aclarke

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Re: makita 6421 muffler mod
« Reply #16 on: September 14, 2014, 06:39:49 pm »
Gonna be offensively loud at 1 to 1 ratio for a work saw. 

Offline 660magnum

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Re: makita 6421 muffler mod
« Reply #17 on: September 14, 2014, 07:05:19 pm »
I ran a 30cc model airplane engine for a couple hours one day with no muffler. My ears were messed up for a couple days.
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Offline pigpen60

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Re: makita 6421 muffler mod
« Reply #18 on: September 14, 2014, 08:51:44 pm »
ok, well if I leave the in and out the same as stock and just remove the cat I should be breathing better. correct?

Offline 660magnum

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Re: makita 6421 muffler mod
« Reply #19 on: September 14, 2014, 10:38:20 pm »
Removing the catalytic part from the muffler does away with a lot of heat and weight.
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
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