Honda GX620 V-twin muffler swap

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  #1  
Old 02-03-11, 08:10 PM
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Honda GX620 V-twin muffler swap

I have this in a Powermate Pro 11000, would like to know if anyone has tried an automotive style muffler with fabrication or used the alternative muffler with any success?

It's not terribly noisy, but I would like to try to cut some db down a little. I will prob build a small enclosure for it with sound-deadening material (2nd question) but looking to see if anyone has tried this.

If I build an enclosure, I will make air accessible to the motor. I plan on having the exhaust side of the enclosure swing out like a barn-door and probably a cutout for the intake on the front of the motor.

Would like to start with the exhaust, neighbors aren't too close but running all night i'm not trying to make enemies either.
 
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Old 02-04-11, 05:42 AM
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I have several quiet Honda EU series generators and it's interesting to look at them and see the lengths they go to to quiet things down. They use a larger than normal muffler so when running the exhaust is a non-annoying low pitch sound. The enclosure is complete and all doors are gasketed. It looks like they did some shaping of the intake, air filter and it's housing to control noise escaping through the carb. Cooling air is channeled around some barriers (baffles) I assume so there is no direct path for sound to get out and the housings are lined with sound deadening foam.

Long ago I had a very noisy generator with a side valve engine. I replaced the stock muffler with a small automotive one which helped with the exhaust noise but it was still quite noisy with a lot of sound coming from the intake and right through the engine case. In the end I considered the muffler mostly a failure so I built a cement block enclosure around the generator. It was just a four sided box about 3ft. tall and totally open on the top which helped reduce the higher pitched sounds somewhat but you had to wear ear plugs to start or shut it down. I think if the walls where higher and not smooth it would have worked better.
 
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Old 02-04-11, 07:21 AM
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Yeah I agree, the sealed-type enclosures are crazy quiet, my cordless drill is louder...ha.

Here's the setup in question, this is the muffler currently installed.



This muffler here is a Honda replacement, may or may not clear the oil filter.



I may need to raise the tank for this one if it even clears the generator but just another option.



Would like opinions if anyone has any of these mufflers and can compare them, mainly the smaller automotive style.
 
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Old 02-14-11, 07:18 PM
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I can remove the muffler, the exhaust headers are 1.25" ID, I would need a reducer that's 1.25" on one end and I can figure out something later.

I looked at a few different sites and could not come up with any reducer that's 1.25" on one end, if anyone that has fabricated exhaust systems let me know what I can use for this size.

1.25" should be the OD.
 
  #5  
Old 02-16-11, 02:31 PM
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What kind of temps should I be looking at for the heads and exhaust at the manifold bolt and near the collector? I want to monitor these temps to be sure whatever I do I can keep the temps the same or lower, in a safe range to be more specific.

I've only run the factory exhaust at no-load at 3600 RPM and had about 220-230 at the head near the exhaust and about 330 ish on the exhaust pipe about 1" from the head.

The Y-collector I was getting around 400-430 deg and the muffler inlet was 320 deg.

Would the collector be that much warmer from a flame kernel or the likes? I can't imagine it would come out that far if any flame at all but just curious.

Granted this was no-load, also looking to know what the range is for a good load.


 
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