.png "Powered by vBulletin")
Greetings to the Collective Wisdom. I know this topic has been talked around and about quite a bit, but I don't think I have found the answers to help me yet. So here goes.
This winter, I removed the original, old, rusted out megaphone mufflers from my 1980 GS550L. Along with them, of course, came the exhaust and crossover pipes. The pipes were in very good shape, so I took the setup down to a welder and had him cut off the old mufflers, then weld on an eight-inch extender/stub that is sized to receive new slip on mufflers. I retained all the other original mountings, header fittings (new gaskets, of course) the crossover, etc. His work was marvelous, even down to aligning the new stub so the axis of the piping and slip on mufflers matches the original alignment. Worked like a charm with the new, shiny, turnout mufflers I have put on the bike. Sounds way way better too than the sputtery, whiny, sound of the megaphones.
I knew in the process about the potential that backpressure would be reduced, as the new mufflers have fairly basic baffles, and none of the fiberglass wrapped stuff. Sure enough, after about a 10 mile test ride, the sparkplugs started to just show a bit of gray-white coloring, so I'm guessing I am indeed running a little lean, presumably as a result of the decreased backpressure on the exhaust system. So I think I have several choices and want the opinions of others.
1) I could rejet the carbs, but I would really rather avoid the cost and changes to the motorcycle. I see this as my least preferred choice and would like to reserve it in case all other options fail.
2) I could buy a different pair of mufflers, more like the original megaphones. I see this as preferrable to rejetting, but I sure like the sound of the new turnouts. Maybe a little louder still than I would like, but definitely quieter than the old burnt out megaphones, and they give a much nicer rumble, more "motorcycle like" if you know what I mean. Now, I have never heard the original megaphones in their like-new condition, so if someone told me they would be deep and rumbly, I could definitely go after this option.
3) I could get a packing kit with fiberglass and baffle insert that would fit inside the current set of turnout mufflers. With experimentation, it seems I should be able to use these to reduce backpressure to a close approximation of the original system. The secondary benefit is it should keep the rumble but reduced by a few decibels, which I would actually like. Problem is, I don't know if this will work (is the theory totally wrong), be a waste of time ('cause it will blow out or need replacing every 3 months or something), or will it drive the backpressure too far the other way and leave me running way too rich.
4) Other options? I have seen mention of baffle disks, or some such similar thing, and cones and outlet size reducers that fit over the end of the muffler, but I have no clue what these are or whether they could work. So any ideas I haven't come up with?
Look forward to hearing other thoughts and suggestions on how best to proceed. TIA for any help. Best regards...
...Ross
This winter, I removed the original, old, rusted out megaphone mufflers from my 1980 GS550L. Along with them, of course, came the exhaust and crossover pipes. The pipes were in very good shape, so I took the setup down to a welder and had him cut off the old mufflers, then weld on an eight-inch extender/stub that is sized to receive new slip on mufflers. I retained all the other original mountings, header fittings (new gaskets, of course) the crossover, etc. His work was marvelous, even down to aligning the new stub so the axis of the piping and slip on mufflers matches the original alignment. Worked like a charm with the new, shiny, turnout mufflers I have put on the bike. Sounds way way better too than the sputtery, whiny, sound of the megaphones.
I knew in the process about the potential that backpressure would be reduced, as the new mufflers have fairly basic baffles, and none of the fiberglass wrapped stuff. Sure enough, after about a 10 mile test ride, the sparkplugs started to just show a bit of gray-white coloring, so I'm guessing I am indeed running a little lean, presumably as a result of the decreased backpressure on the exhaust system. So I think I have several choices and want the opinions of others.
1) I could rejet the carbs, but I would really rather avoid the cost and changes to the motorcycle. I see this as my least preferred choice and would like to reserve it in case all other options fail.
2) I could buy a different pair of mufflers, more like the original megaphones. I see this as preferrable to rejetting, but I sure like the sound of the new turnouts. Maybe a little louder still than I would like, but definitely quieter than the old burnt out megaphones, and they give a much nicer rumble, more "motorcycle like" if you know what I mean. Now, I have never heard the original megaphones in their like-new condition, so if someone told me they would be deep and rumbly, I could definitely go after this option.
3) I could get a packing kit with fiberglass and baffle insert that would fit inside the current set of turnout mufflers. With experimentation, it seems I should be able to use these to reduce backpressure to a close approximation of the original system. The secondary benefit is it should keep the rumble but reduced by a few decibels, which I would actually like. Problem is, I don't know if this will work (is the theory totally wrong), be a waste of time ('cause it will blow out or need replacing every 3 months or something), or will it drive the backpressure too far the other way and leave me running way too rich.
4) Other options? I have seen mention of baffle disks, or some such similar thing, and cones and outlet size reducers that fit over the end of the muffler, but I have no clue what these are or whether they could work. So any ideas I haven't come up with?
Look forward to hearing other thoughts and suggestions on how best to proceed. TIA for any help. Best regards...
...Ross
Yes, the sound will go down, but it likely won't sound the same, only quieter. When you pack the canister, it changes the frequency response and the sounds coiming out will not be the same as before. Yes, packing will blow out. It should not happen in 3 months, but you can figure on repacking every couple of years. If the old mufflers were OEM, I can't imagine you would end up with more restriction and rich jetting by repacking these mufflers.
Comment