Carbon Buildup inside left pipe
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Joined: May 2013
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From: Roswell
Carbon Buildup inside left pipe
My FLHTK M8 has stage 1 done with a Dyno Tune at the dealer. The left exhaust has a fairly heavy carbon deposit inside the left muffler end cap.
I understand only about 25% of exhaust goes through the left side, so why does all the carbon take the low road? Anyone know?
Also, I noticed that the back of the bike gets dirty after even a short ride.
I understand only about 25% of exhaust goes through the left side, so why does all the carbon take the low road? Anyone know?
Also, I noticed that the back of the bike gets dirty after even a short ride.
Tourer
Joined: Apr 2014
Posts: 499
Likes: 164
From: Houston
There is alot less pressure coming out of the left side. Also the left side has hard 90 degree bend causing it to be cooler than the right side. The increased heat burns up the soot on the right side and the increased pressure coming out clears the rest of it. So the right side will always be cleaner than the left. Only way to solve that issue is a good 2-1. Now the back getting dirty, only way to solve that is not to ride it. The best way to justify it getting dirty is to ride a lot of miles each outing and the miles to dirty ratio will go down. 
But I agree they get dirty after just a few miles. Enjoy the ride man.
But I agree they get dirty after just a few miles. Enjoy the ride man.
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Joined: Nov 2008
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My FLHTK M8 has stage 1 done with a Dyno Tune at the dealer. The left exhaust has a fairly heavy carbon deposit inside the left muffler end cap.
I understand only about 25% of exhaust goes through the left side, so why does all the carbon take the low road? Anyone know?
Also, I noticed that the back of the bike gets dirty after even a short ride.
I understand only about 25% of exhaust goes through the left side, so why does all the carbon take the low road? Anyone know?
Also, I noticed that the back of the bike gets dirty after even a short ride.
Outstanding HDF Member
Joined: Dec 2017
Posts: 2,493
Likes: 1,051
From: Atlanta
There is alot less pressure coming out of the left side. Also the left side has hard 90 degree bend causing it to be cooler than the right side. The increased heat burns up the soot on the right side and the increased pressure coming out clears the rest of it. So the right side will always be cleaner than the left. Only way to solve that issue is a good 2-1. Now the back getting dirty, only way to solve that is not to ride it. The best way to justify it getting dirty is to ride a lot of miles each outing and the miles to dirty ratio will go down. But I agree they get dirty after just a few miles. Enjoy the ride man.
But I agree they get dirty after just a few miles. Enjoy the ride man.
Seasoned HDF Member
Joined: Feb 2008
Posts: 23,001
Likes: 11,441
The HD exhaust is a scavenger. It favors one side to increase torque works some what like a 2-1. But the design balances the best of both worlds. Nothing new. Less flow on the one side makes for a cooler exhaust. The system works well.
Likely your Tuner cranked the fuel ratio up a bit more than needed . May want to have him adjust that.
Likely your Tuner cranked the fuel ratio up a bit more than needed . May want to have him adjust that.
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There is alot less pressure coming out of the left side. Also the left side has hard 90 degree bend causing it to be cooler than the right side. The increased heat burns up the soot on the right side and the increased pressure coming out clears the rest of it. So the right side will always be cleaner than the left. Only way to solve that issue is a good 2-1. Now the back getting dirty, only way to solve that is not to ride it. The best way to justify it getting dirty is to ride a lot of miles each outing and the miles to dirty ratio will go down. But I agree they get dirty after just a few miles. Enjoy the ride man.
But I agree they get dirty after just a few miles. Enjoy the ride man.HD Forum Stories
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