Back pressure.
Someone suggested that trick for my straight pipes back in '83ish on my shovelhead.
I thought he was a loon.....
Didn't learn he was smarter than me for some years....
I roll my eyes with the negative Nancy’s that run there mouth saying they tried drag pipes and they suck (like you S&S video… guys a moron) you can’t stick some stupid chopper craze 20” long cut off drag pipes on a bike and make it run.. so then you assume all drag pipes are bad and walk out with the S&S clown and throw them in the dumpster so you can sell your dumb one size only fits one size 2 into 1 pipe.
Generally the right drag pipe on the street for an 80 to 88” motor will be a 1 3/4 diameter 32 to 40 inch long set of equal length pipes. A high compression 96-113 is on the fence with 1 3/4 to 2 inch diameter and over 113 inch motors NEED a 2 inch diameter pipe. I’ve even seen high compression 98 inch shovels benefit from 2 inch diameter pipes before.
Last edited by Rains2much; Feb 18, 2026 at 09:10 AM.
The 305.4 cc (18.64 cu in) overhead cam engine had a redline of 9000 rpm and contrasted sharply from the low-revving European and American bikes of the day. Running straight pipes with small internal baffles, CL77s featured a loud and very distinct sound from the 180 degree firing order of this parallel twin. Many of these motorcycles featured aftermarket snuff-or-nots (commonly misspoken as "snuffer nuts"), which featured a flat washer like piece of metal which pivoted just inside the tips of the exhaust pipes to quiet or increase the sound of the exhaust at any time during operation simply by twisting the external ****.
In later years Honda joined the end of the exhaust pipes with an external factory installed muffler to control exhaust noise. At first it was slipped on and clamped. Later models came with only one of the twin side pipes welded onto the slip-on muffler. The last version came with both pipes welded to the slip-on muffler.
Image and text from Wikipedia.
They really did sound great!
Last edited by Beartooth Rider; Feb 18, 2026 at 09:56 AM.
The 305.4 cc (18.64 cu in) overhead cam engine had a redline of 9000 rpm and contrasted sharply from the low-revving European and American bikes of the day. Running straight pipes with small internal baffles, CL77s featured a loud and very distinct sound from the 180 degree firing order of this parallel twin. Many of these motorcycles featured aftermarket snuff-or-nots (commonly misspoken as "snuffer nuts"), which featured a flat washer like piece of metal which pivoted just inside the tips of the exhaust pipes to quiet or increase the sound of the exhaust at any time during operation simply by twisting the external ****.
In later years Honda joined the end of the exhaust pipes with an external factory installed muffler to control exhaust noise. At first it was slipped on and clamped. Later models came with only one of the twin side pipes welded onto the slip-on muffler. The last version came with both pipes welded to the slip-on muffler.
Image and text from Wikipedia.
They really did sound great!
Back on topic, the reversion problem with open exhaust gets conflated with back pressure.
Back pressure does mitigate reversion, but there will still be a loss of torque at lower RPM.
Regarding the need for a tuner, intuitively we should all want to run the correct Air/Fuel Ratio and Ignition Timing in our builds.
Back on topic, the reversion problem with open exhaust gets conflated with back pressure.
Back pressure does mitigate reversion, but there will still be a loss of torque at lower RPM.
Regarding the need for a tuner, intuitively we should all want to run the correct Air/Fuel Ratio and Ignition Timing in our builds.
No 3 week waiting list, load on a truck, drive an hour, wait.. pay $350-$550.. load, drive home and then be held hostage if you wanna try different pipes or a cam.. just throwing it out there.
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