Exaust change and mixture ratio

[k3new]

I am trying to get a handle on how switching flow via exhaust changes can lean out a bike with either FI or carbs. On intake, the exhaust valve is closed, and vise versa, right?

Can someone succinctly explain this, or point me to a web site?

Thanks,

Joe

[intimid8er]

Originally Posted by k3new

I am trying to get a handle on how switching flow via exhaust changes can lean out a bike with either FI or carbs. On intake, the exhaust valve is closed, and vise versa, right?

Can someone succinctly explain this, or point me to a web site?

Thanks,

Joe

A freer flowing exhaust increases the amount of air flowing through the engine.

Check this article, it may get you going in the right direction.

http://www.motorcyclecruiser.com/tech/jetkit/index.html

[VettePilot]

Originally Posted by intimid8er

A freer flowing exhaust increases the amount of air flowing through the engine.

During the exhaust stroke, a free flowing exhaust allow the engine to push the exhaust out with less effort compared to a restrictive exhaust. During the intake stroke, when the engine draws in the air/fuel mixture, the exhaust valve is closed. Whether there is no exhaust or a 30 foot long exhaust pipe with a banana in it won't matter during intake, where the fuel is mixed with air. Please correct me if I'm way off.

http://auto.howstuffworks.com/engine3.htm

[ssjd]

I am also curious about this as well because most of the things I have read say how pipes will lean it out but I had an experience with a 1100 vstar that after putting on a hard krome 2into1 it got so rich the plugs had to be changed every couple hundred miles.

[cobra marauder]

I just put Cobra slash out slip ons on my 98 Marauder. Didnt realy notice that much change in the bike other than the great sound and it being about 20lbs lighter than stock mufflers. I had the local tech have a look at it just to make sure though. He said it realy wasnt that bad but he did tweek the carbs a little. I asked him about rejetting. He said he isnt a big fan of this, unless you cant get the carbs adjusted enough. He told me that he remove the cab slides and shimmed the needles, removed material from the plastic spacers, drilled low speed fuel screws out and readjusted. WHAT EVER ALL THAT MEENS, MAYBE SOMEONE CAN EXPLAIN TO ME. All I know is it run a lot smoother. I noticed before that when I gased on it hard that I felt a low vibration in the bike, now it is smooth and just takes off hard and quik. So I am very happy.