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Exhaust Back Pressure??

856 Views 4 Replies 4 Participants Last post by  doug
Okay tech guru’s I have an interesting question for you…how much back pressure does a motorcycle really need??

I will clarify I have a 1995 ZX6c (Ninja 600R) and for a while I have noticed that my exhaust is far louder than most and that my exhaust can is never very hot, I started thinking that maybe I had a hole in my pipe so I checked it out…sure enough there was a rather large hole in the end can right were the pipe meets the can. I started to think about whether this “performance wise” was a good thing or a bad thing. Obviously bike motors need some back pressure but how much is enough?? Is having a hole in the end can actually beneficial (I am thinking to the old 70’s bike they use to straight pipe for performance and sound). I am about to put in a jet kit and k&n air pods and a 4 degree timing advancer but I am wondering if I am going to have to fix the exhaust pipe first to actually get the better performance out of it…but what do the pros think??

Any and all help is greatly appreciated
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Back pressure helps with the lower end of the RPM scale to make the bike pull harder. But on the top end near redline you want as little resistance to flow as possible.

This is what the Yamaha EXUP valve does for the bikes that use it. It's a control valve in the exhaust system that closes it down a lot at idle and for the first few thousand revs then opens progressively as the revs climb until probably about 5000 to 6000.

So technically your leaking system will be making the engine run leaner and at the same time making your pull aways from stops more boggy.

And yes you really should fix the system before you do all that engine work. If you don't then you'll need to fine tune the idle mix and needle height all over again when you finally get around to fixing the exhaust.
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