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- Jul 24, 2002
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A buddy in our club was running a gas mono at our new site and his little stinger muffler wasn't quite gettin' it, so I offered to "internalize" his pipe:
I use a length of brass tubing with a short piece of the next larger size soldered to the end, tube should extend to about the middle of the widest part of the pipe. For 3.5cc I use 11/32" (0.312" I/D), 7.5's 13/32" (0.375" I/D), 11cc and up including 27cc gas motors 15/32" (0.437" I/D). You may need to stretch the stinger slightly, on aluminum pipes you can heat it with a torch and use increasingly bigger drill bits to work it out, or if there's enough material you can just drill it out. You can use the next smaller size tube but watch for excess motor heat in hot conditions.
I drill a small (1/16") drain hole near where the tube meets the stinger, this way you can drain the pipe if you take a dunk or flood the engine. I like to use Locktite to hold it in and it works well if it's a close fit, others have said JB weld works if the fit is looser. This simple mod brought my 11cc rigger from around 102 dB to about 91. If I use a small stinger muffler (Muck, Prather, T-Mod etc) the result is a very quiet running boat of around 88 dB. I haven't seen any power loss or excess heat doing this since the '03 season.
I use a length of brass tubing with a short piece of the next larger size soldered to the end, tube should extend to about the middle of the widest part of the pipe. For 3.5cc I use 11/32" (0.312" I/D), 7.5's 13/32" (0.375" I/D), 11cc and up including 27cc gas motors 15/32" (0.437" I/D). You may need to stretch the stinger slightly, on aluminum pipes you can heat it with a torch and use increasingly bigger drill bits to work it out, or if there's enough material you can just drill it out. You can use the next smaller size tube but watch for excess motor heat in hot conditions.
I drill a small (1/16") drain hole near where the tube meets the stinger, this way you can drain the pipe if you take a dunk or flood the engine. I like to use Locktite to hold it in and it works well if it's a close fit, others have said JB weld works if the fit is looser. This simple mod brought my 11cc rigger from around 102 dB to about 91. If I use a small stinger muffler (Muck, Prather, T-Mod etc) the result is a very quiet running boat of around 88 dB. I haven't seen any power loss or excess heat doing this since the '03 season.
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