A little trick modification in place of those after market baffles!
I have been testing in a no baffles, wide-open exhaust configuration which is great for WOT, (wide open throttle, racing).
Now to add some back pressure back into my "Baron's Nasty Boy Slashers", fatten up the torque curve and make it more street able, I needed a good baffle that added pressure, yet allowed a good flow of exhaust gasses.
I got rid of the 11/4 inch round crimped baffle/pipe that came with the mufflers; because I really hated the way they sounded and was not pleased with the performance.
I looked at after market baffles that cost between $18.00 and $43.00 per baffle and yet none sounded like I wanted it to. Even the for racing only use, straight tube baffles were $21.50 each.
A exhaust tech tip from Scott at J&P Cycles tells us: "Ideal gas velocity is 300 feet per minute and a variety of factors influence this important goal. Remember, too fast is as bad as too slow. Without going into the math involved, the 883'cc, 1200'cc and 1340'cc need a 1 3/4" pipe to stay near this gas speed."
So I made a racing type baffle out of 1 ¾ inch pipe with a total overall length of 9 1/2 inches. I also made a 5 1/2 inch baffle that I like the most around town cruising. This is still a straight open 1 ¾ inch pipe, but the 5 1/2 inches length gives the exhaust gas lots of backpressure as it collects in the muffler body prior to finding the opening of the 1 ¾ inch pipe/baffle and exits out. If you feel like experimenting you can make several sets of baffles at different lengths 9.5", 7.5", 5.5" 2.25" etc. and actually feel the torque curve move up the RPM range as you shorten it.
Click to see larger graphic
The 9 ½ " baffle gave gobs of felt torque off idle to the low 5,000's RPM range, as the 5 ½" baffle moved the power felt curve from 1500 RPM to mid 6000 RPM range. This seems to have worked very well and is a big boost to low-end torque as compared to no baffles.
This has knocked off the "hard edge sound" it had with out the baffles. It is a deeper, mellower sound, until I crank the throttle open and it also got rid of the raping down frapping on deceleration.
I also adjusted the PMS in , (leaner), 1/4 turn. From 3 turns out to 2&3/4 turns out from closed. If you jetted and set your carbs for no baffles, this is needed to avoid spark plug fouling from the the added back pressuer.
**Here is a great web site Night Rider. It has alot of Exhaust Info on "Making Drag Pipes Work". It is a simple Adjustable Baffle that works and has dyno sheet to prove it, but they are still loud!
Have Fun & Ride Safe
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