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Post by twitch on Jan 20, 2008 17:32:41 GMT -5
I had someone give me a muffler that is 1.5" straight through. Is that too big for a 150cc that has NOT been jetted? I have no problem using a thick walled pipe, or even doubled pipe to make the opening thinner if I need to. Could i just make the exit side of the muffler narrower by using a washer? And if I Do need to use a smaller pipe all the way through, how many holes should I drill in the pipe and what size holes?
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Post by loudest143 on Jan 20, 2008 18:06:01 GMT -5
I can't answer your question directly, as I failed to build a successful exhaust mod. I liked it but the bike didn't. You should check in the tips and tricks forum, as there are a few threads there, both past and present that talk about exhaust mods and proper sizing concepts.
loudest143
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Post by twitch on Jan 21, 2008 18:12:16 GMT -5
Well, If the header tube coming off the engine is still the 1" pipe, isnt the muffler only really going to shange the sound? I mean, the inlet and outlet of the muffler is only 1.5". I repacked the whole muffler tightly with steel wool to try and keep it somewhat on the quiet side.
The whole length is only 12" from inlet to outlet. Any more ideas on this folks? I hope to have it installed tomorrow, but would like to hear from a few of you before I do.
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Post by loudest143 on Jan 21, 2008 20:41:52 GMT -5
Steel wool? You may wanna look over on the tips and tricks forum and see how that worked out for another dawg. Stuff got melted. I'm not sayin', but check out yer local motorbike shop and buy some muffler packing. I bought some for 9 bucks, and it's not on fire. Yet. There are some different opinions on this size of the pipe topic. I'm still trying to find some real numbers on this..... I did find some interesting facts on the Whitebros.com site, regarding their universal e-series exhaust. I've got one on the way, and their pdf was pretty helpful, complete with re-jetting stats. Check it out, it's free.
loudest143
*scootbike or sportbike, I dunno.
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Post by twitch on Jan 21, 2008 21:11:26 GMT -5
Loudest, i am sure you have done more research on exhaust size than I have, no doubt. But i did see on the tips and trick board that someone said the reason the steel wool melted, was in fact because it was "brass wool". He suggested using the stainless steel coiled type of wool. That is what i used. I guess at this point i am sort of commited to finishing the project. I will post on how it goes. Thanks for the replies.
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Post by daddyeby on Jan 21, 2008 21:19:24 GMT -5
I had a dirt bike as a kid it had a racing pipe on it loud as all get out my dad put steel wool in it and too it for a test spin it blew out in a red hot mass of molten steel.
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Post by Jacine on Jan 21, 2008 21:36:51 GMT -5
Is this a slip on to an existing pipe or a straight through exhaust?. Even if it is a slip on, there may be need to adjust the air fuel mix and rejet. Most likely the air fuel mix though. The muffler will change some of the back pressure and some of the wave resonance so the tendency is to run lean.
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Post by loudest143 on Jan 21, 2008 21:43:10 GMT -5
Hey twitch, I just wanted to make sure you saw some of the past results of mods. I guess I didn't read as closely, and bucked the established train of thought, and now I'm waiting for my aftermarket muffler to show up to finish my tuning project. Don't wanna see you fall down that same pit, without speaking up. Post your results we all may learn something!
loudest143
I wish I looked good in thigh highs like jacine.
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Post by twitch on Jan 22, 2008 10:11:47 GMT -5
Dont get me wrong, I do appreciate the replies and advice. I think the hardest part for me is gonna be getting it mounted. If it does infact melt the wool, I will then go buy some packing material. I figured the wool would have to be better than what came out of it. When i pulled the cap a small lone peice of packing material about the size of a crumbled piece of paper fell out.
Jacine, this is replacing my existing can, but I am still using the 1" header pipe up to the flange. I know there are no baffles in this muffler as I can look right through it. If I have to go up in jet size I dont think i would mind that too much. They seem to be cheap enough. I just hope it doesnt sound quite as loud as it did without any muffler on it. Man I tell ya, it sounded like a harley with no muffler at the flange.
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Post by leo on Jan 22, 2008 10:35:38 GMT -5
it's my understanding that the exhaust doesn't play much role in the performance of a 4 stroke engine. the real advantange would be in making it easier for the engine to breath. there is the possibility of the exhaust being too restrictive. in this case it will cause the engine to overheat.
2 stroke engines are an entirely different matter. these types of engines are so picky about exhausts that you practically must tune each engine. by that i mean that a exhaust for one 50cc will not be perfect for another 50cc. the major deal is being able to exhaust the burnt fuel without the next charge having chance to enter the exhaust port.
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Post by Jacine on Jan 22, 2008 11:23:03 GMT -5
Dont get me wrong, I do appreciate the replies and advice. I think the hardest part for me is gonna be getting it mounted. If it does infact melt the wool, I will then go buy some packing material. I figured the wool would have to be better than what came out of it. When i pulled the cap a small lone peice of packing material about the size of a crumbled piece of paper fell out. Jacine, this is replacing my existing can, but I am still using the 1" header pipe up to the flange. I know there are no baffles in this muffler as I can look right through it. If I have to go up in jet size I dont think i would mind that too much. They seem to be cheap enough. I just hope it doesnt sound quite as loud as it did without any muffler on it. Man I tell ya, it sounded like a harley with no muffler at the flange. Actually that's what the Harley aftermarket pipes do, is remove baffles and create flowthough. But with harleys you have to remap the ECM (equivalent of rejeting and adjusting the carb) because they run extremely lean. You might want to use a high flow air filter while your at it. |
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Post by twitch on Jan 22, 2008 13:30:44 GMT -5
Jacine, I already have a K&N cone style air filter coming off my carb, so I think my intake is taken care of. I actually got it mounted and fired up, and I gotta tell ya, I like the sound. With no muffler at all it was loud with alot of popping, but with this it sounds like a properly tuned v-twin. Well, as close as a 150cc can come to that sound. Very deep low tone, and not overpoweringly loud, and its is better once you get to speed. I think now the only concern is wether the steel wool will blow out, or stay put. I really packed it in there tightly so I doubt it will blow to one end, but I guess melting is another story. I will post pics in a while.
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Post by natefromogden on Jan 22, 2008 14:52:41 GMT -5
Once you get the muffler mounted, you can begin experimenting with jet sizes, washers on the outlet and extra holes drilled. Note that I said experiment. There are no guidelines or hard, fast rules for changing your exhaust around. All you can do is hook everything together, run it, examine your spark plug for color and decide where you go from there. The 1.5" diameter is probably not too big or too small but you can expect to tinker with jets and oulet diameters to get the best results.
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Post by earlwb on Jan 22, 2008 14:56:04 GMT -5
You can likely get a slip on adapter from many auto parts stores.
The last time I went in AUTO ZONE they had a whole shelf of assorted different sized tubing for adapting different exhaust systems to different things.
Many muffler shops or welding shops can help you weld up a adapter too, if you need one.
Then if it is too free flowing, you can get them to tack weld in a large washer or something to restrict it some more.
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Post by twitch on Jan 22, 2008 17:03:41 GMT -5
i had one of my connections come loose on me. I dont trust JB weld anymore after this. Anyway, I got it back together and she sounds the same, but I am getting some backfireing now. Does that mean I am too rich? That doesnt sound right to me. Can you backfire if you are running lean?
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Post by tp555 on Jan 22, 2008 19:13:33 GMT -5
Backfiring out the exhaust is caused by lean conditions not rich.
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Post by twitch on Jan 22, 2008 20:11:09 GMT -5
I always thought backfire was from gas getting through the combustion chamber and detonating in the exhaust pipe. Well i learn something new everyday. Anyway, the adjustment screw on the side of my carb (air/fuel?), do I screw it in to lean or richen the mix?
In other words is it out=rich, or in=rich?
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Post by Aerostudent on Jan 22, 2008 21:51:00 GMT -5
In=less_air=rich from what I know, but this would be far from the first time I was wrong.
Aero
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