Is backpressure important?

BigNorm

Boobie Inspector
Joined
Apr 30, 2016
Messages
3,430
Location
Minden, NV, USA
Ride
2014 Rocket 3 Touring
It looks like the backpressure issue is handled with whatever size pipe is used on the header. Is it important to tune the pipe for the pressure coming out? I know on the HDs this was extremely important. You could tell a significant torque difference from running with or without the muffler.
 
My muffler is a turbo. I've got plenty of torque!! Yes, back pressure matters when it comes to torque on any bike.
 
I installed a set of D and D's on my bike and decided to pull the baffles out just to give her a try. She fell flat on her face under hard acceleration running highway speeds.
 

What is back pressure?
 
R-III-R Turbo said:
What is back pressure?
Click to expand...

The stuff you have very little of in your two rides there. Apparantly some is good for low end torque. I had a hard time believing it until I ran without a pipe when I put it all back together to test it then I put the pipe back on and lots of seat of the pants torque emerged. I think a lot has to do with where you want your power.

It's also what I got after riding 7 hours on a stock R3 seat.
 
Ah very good. I always thought the pressure in your tailpipe was caused by the exhaust gas pulsing out
 
It's the restriction of the geometry and sizes of the pipework preventing the gasses flowing freely. This allows the pressure to build up before it gets out and is deemed back pressure.
 
Blackthou said:
This allows the pressure to build up before it gets out.
Click to expand...

Ah right so the pressurised charge of gas that blows out the cylinder increases in pressure in the exhaust pipe due to restrictions?
 
That's about it. On a road bike you need a balance, on a 2 stroke it's essential but on racing bikes they're tuned for less is better.
 
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