expansion exhaust

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jpullen

jpullen

New Member
Sep 18, 2013
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Damascus GA.
I am running a grubee sky hawk gt5 angel fire with CNS carb (tuned at long last) and stock black cat muffler. I'm thinking of getting a stinger high performance expansion chamber tuned pipe with muffler on the end from that'sdax. I have read a lot of mixed reviews on this type product. Most every one says the SBP pipe is the way to go but I don't want to have a three piece muffler held together with silicone hose segments. I ride on rough county maintained paved roads and rough dirt roads and I'm not sure the SBP would stand up to it. I am not looking for more speed just better low to mid range power with out getting to loud. Also would a mm billet intake help my set up?
 
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spanners

New Member
Oct 5, 2011
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east coast Australia
I have tried three expansion chambers and the SBP pipe has been the best by far. You could find someone to weld the header pipe together it wouldn't be costly .
With the MM manifold, I have one on my bike and would never go back to a stock one.
Cheers spanners
 
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maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
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memphis Tn
I build my own from pocket bike pipes I get from scooter store junkpiles, but I have a welder.
You could always do like spanners says and get the sbp pipe welded solid once you have it setup. Most muffler shops can do the welding fairly cheap if you don't know someone with a welder.
Either way, a tuned pipe will really make you happy you took the time!
 
jpullen

jpullen

New Member
Sep 18, 2013
27
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Damascus GA.
Welding is no problem. I have a mig welder at the house and an oxi/acetylene brazing torch. I was initially going to gut the stock muffler replace the 1/2 inch pipe from mounting flange to muffler with 3/4 electrical conduit and weld the cap back on and put a silencer on the tip but didn't know if that would work. Thanks guys for the info.
 
jpullen

jpullen

New Member
Sep 18, 2013
27
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Damascus GA.
Also I have a very slight tilt on my motor. It isn't to bad with the offset manifold but will the mm intake need to be perfectly level?
 
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spanners

New Member
Oct 5, 2011
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east coast Australia
You can do all the mods you like on a stock pipe it will never be as good as an expansion chamber, with the MM manifold it dose not have to be perfectly level, I have never heard of one causing a problem
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
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memphis Tn
Since you can weld, I suggest building your own pipe to fit YOUR bike perfectly.
The store pipes have to be a compromise to fit more than one bike, but a custom pipe can be built easily and will fit better than 99% of the aftermarket bolt on's.
You can tailor the power to fit your needs and equipment without having to settle for whats available.
Good rules of thumb when fabbing a pipe:
Short and fat = torque in low and midrange
Long and slender = high end rpm
Keep the header around 12" to 16" inches from port to chamber when starting for best results
Tune with header length once you get close to the kind of power you want.

Here are a couple different pipes I've built lately...
My current ride, The Pig ver 2

The Pig ver.1

Original Pig ver. 1

Original Pig ver.2
 
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jpullen

jpullen

New Member
Sep 18, 2013
27
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0
Damascus GA.
Custom build it will be then. You guys twisted my arm now im going to be out in the shed playing like a kid for a few days. Once the expansion chamber gets here that is. Header 12-18 inches long short and fat for low to mid range power. Are there any other basic rules of thumb or exhaust pitfalls I should know about before I get started. I will also need to rejet carb when I put the new set up on correct?
 
maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
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memphis Tn
You will probably have to rejet to get full effect from a tuned pipe, but it depends on too many things for any solid rule to cover.
None of my pipes required a jet change, just a needle adjustment for more fuel.
But then again, none of my pipes was built for max performance. I prefer a nice wide torque band rather than max hp.
You decide what you want and build accordingly.
Don't be afraid to experiment with header length and chamber placement to find your personal happy place.
 
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