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Tuner + Cat = Increased heat?

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Old Jul 29, 2011 | 04:01 PM
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pettifogger1's Avatar
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Default Tuner + Cat = Increased heat?

Lots of tuners are advertised for the 10 and up touring bikes and make no mention of the catalytic converter. Cats burn unburned fuel. If you add fuel to cool the engine that means there will be more unburned hydro-carbons reaching the cat. Won't that increase the heat coming from the cat? If so, it seems like engine heat has been traded for cat heat.
 
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Old Jul 29, 2011 | 04:15 PM
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Gut the cat; remove it.
 
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Old Jul 29, 2011 | 04:56 PM
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Originally Posted by kerrycorcoran
Gut the cat; remove it.
The tech at my dealership...yes the dealer...actually recommended I do this to finish off my stage one (actually he recommended getting a new header pipe without the cat, not gutting the stock pipe), and he didn't even say "void the warranty" after it!

If your cat theory is correct, then how is it that you can get decel pop, which is unburned fuel reaching your now bigger, better breathing mufflers and combusting? Shouldn't that fuel burn in the cat if you are correct and never make it all the way back there?

Just a question from a non-techie person.
 
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Old Jul 29, 2011 | 04:56 PM
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Originally Posted by pettifogger1
Lots of tuners are advertised for the 10 and up touring bikes and make no mention of the catalytic converter. Cats burn unburned fuel. If you add fuel to cool the engine that means there will be more unburned hydro-carbons reaching the cat. Won't that increase the heat coming from the cat? If so, it seems like engine heat has been traded for cat heat.
Catalysts run hot when there is an excess of oxygen. Adding fuel cools them down provided the engine doesn't get to the point of misfiring.
 
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Old Jul 29, 2011 | 07:41 PM
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And, the ECM has enough variable to adjust for making this slight change down the flow process - thus no popping.

Less restriction, more fuel to cool and ECM variance to allow this modification without the need to get it dyno tuned.

If you start to modify at the other end, i.e. CAMS, Air Filter, etc - you could easily need a fuel management or dyno tune to compensate for those changes.
 
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