Exhaust question..

[CanyonCarver]

I just bought a full exhaust for my SV, and I have heard a few different things. I figure their are a few of ya who really know bikes.. So here my question..

Will I run lean with my exhaust? I hear at 5,280 ft every engine runs richer. So in theory, if exhaust leans it, I should be fine. But people are telling me I must get a power commander...

Your thoughts??

[Mel]

Put it on the bike and see what you think of how it runs. Technically I don't think exhaust in and of itself will lean out the mixture on the bike (since leaning out would be too much incoming air mixing with fuel). It will change how the bike runs slightly, but if your bike is fuel injected, the stock map can make up for a lot of the changes you will experience. If you did the exhaust and like a K&N or something like that, then you might start to notice a lil issue (say popping and such from the exhaust). I have 2 fuel injected suzuki's, one of which is a V-Twin, with aftermarket (Yosh) exhaust and stock computers and mapping and they run just fine.

[CanyonCarver]

Mine does pop ( backfire) when I get off the gas. So is this a sign I need something?

[Chris]

It's a sign you should sell that junk ass suzuki.

[Mel]

meh, I think there are a couple schools of thought on that. My twin shoots flames out the pipes when I close the throttle over about 6K RPM. Other than the popping, I do not think there is a performance issue with it, and everyone I have known with a suzuki twin has the same thing happen. There are some articles on tlplanet.com which talk about this same thing and their feelings on it.

[Bueller]

Mine does pop ( backfire) when I get off the gas. So is this a sign I need something?

You need to eliminate the pair valve.
http://www.sv-portal.com/forums/index.php

[rforsythe]

Ok, so a better flowing exhaust can lean out a bike - flowing more air out means it has to come from somewhere. The excess flow will actually suck in more through the intake as the valves overlap, so it can lean things out slightly.

Popping can be the PAIR valve as Bueller said, it can also be an indication of running lean. Try the easy stuff first (like removing that valve).

Mel - you get flame out the exhaust when you close the throttle over 6K because your bike is fuel injected; fuel flow is metered against airflow, and the sudden change in intake manifold pressure is faster than the computer can process, so there's a brief extremely rich mixture getting pushed through. Since there is not enough air to burn all of the fuel, some of it goes out the pipe and ignites there.

Oh, moving this to Bike Tech.

[Mel]

hehe, this is why ralph is a mod and I am not. Thanks for the better explaination ;)

[CanyonCarver]

thanks guys and gals for the info

[motorcycleman]

hehe, this is why ralph is a mod and I am not. Thanks for the better explaination ;)

what happened here?