Being that the Black Widow header is smaller pipe diameter that the Delk or the Area P, it naturally has better low rpm power. Still, it can be better and surprisingly, adding the exhaust reducer actually made more peak power on the test bike I worked on. Again, easily done with parts you can find at any auto parts store.
You will need an exhaust reducer from the local parts store, measuring 2" ID on the entrance side and 1.75" OD (yields 1.625" ID) or 1.5" ID on the exit side.
Some examples: Nickson #17516, AP# 8936 or 8923 ; this is 2"ID to 1.75" OD (1.625" ID)
Nickson 17506, AP# 8922; this is 2" ID to 1.5" ID
Either size will work, if you have a fear of losing top end with the 1.5" reducer use the 1.625" ID reducer. If you want the most low end, use the 1.5" reducer.
You will need to shorten the adapter by cutting and removing most of the large diameter portion of the adapter. Your cut should be just above where the reducer starts necking down. After you cut, clean the cut and do an internal bevel on the leading edge, to ease the flow transition.
Now remove the midpipe and slide the reducer down until it bottoms on the midpipe's flare, where the midpipe reduces to 2". The reducer will be held in place by the header collector when you slide the midpipe back onto the header section. If you need to slide the colleector in a little more to make a little room for the header, shorten the large diameter again, but remember the flared area of the adapter mated to the flared area of the midpipe is what's holding the adapter from sliding down the midpipe. If you feel the adapter is to lose, you can use a hammer and punch. Punch 2-3 small divots from the inside of the largest portion of the adapter outward to tighten it against the midpipe.
Reassemble the midpipe and muffler onto your bike and go try it out. Post up and let folks know what you think!
I will attach the dyno charts from before and after with the 1.625" reducer. This particular bike is low miles, tight, and doesn't give up good top end, but you can see the adapter helped everywhere in the power curve.
Steve
You will need an exhaust reducer from the local parts store, measuring 2" ID on the entrance side and 1.75" OD (yields 1.625" ID) or 1.5" ID on the exit side.
Some examples: Nickson #17516, AP# 8936 or 8923 ; this is 2"ID to 1.75" OD (1.625" ID)
Nickson 17506, AP# 8922; this is 2" ID to 1.5" ID
Either size will work, if you have a fear of losing top end with the 1.5" reducer use the 1.625" ID reducer. If you want the most low end, use the 1.5" reducer.
You will need to shorten the adapter by cutting and removing most of the large diameter portion of the adapter. Your cut should be just above where the reducer starts necking down. After you cut, clean the cut and do an internal bevel on the leading edge, to ease the flow transition.
Now remove the midpipe and slide the reducer down until it bottoms on the midpipe's flare, where the midpipe reduces to 2". The reducer will be held in place by the header collector when you slide the midpipe back onto the header section. If you need to slide the colleector in a little more to make a little room for the header, shorten the large diameter again, but remember the flared area of the adapter mated to the flared area of the midpipe is what's holding the adapter from sliding down the midpipe. If you feel the adapter is to lose, you can use a hammer and punch. Punch 2-3 small divots from the inside of the largest portion of the adapter outward to tighten it against the midpipe.
Reassemble the midpipe and muffler onto your bike and go try it out. Post up and let folks know what you think!
I will attach the dyno charts from before and after with the 1.625" reducer. This particular bike is low miles, tight, and doesn't give up good top end, but you can see the adapter helped everywhere in the power curve.
Steve
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