The Finished Chip Beck Spec CB1100-PHOTOS

[Jteakus_imp]

Nice ride. Curious if you gutted the head pipe before the jet coat or left the catalyst intact?

[feralchimp_imp]

Thanks for the reply on the shocks (and previous asker's question on the tail light...looks super clean!)

[ChipBeck_imp]

Nice ride. Curious if you gutted the head pipe before the jet coat or left the catalyst intact?

Although I have a perfect stock header with the cat removed I chose to coat my original header with the cat. My bike ran really well with the Power Commander 5 and I didn't want to risk screwing it up by lowering the back pressure with no cat. The header had rubber stoppers in all openings when it was coated and polished so the cat was not compromised. The inside of my header is not coated. Cheers bro.

Chip

[PowerDubs_imp]

There is no such thing as good back pressure. That is a never dying fallacy. An engine is an air pump. Anything that makes it less efficient is bad.

The important tuning part is exhaust pulses, and there are many variables to that- pipe diameter, length, transitions, bends, collectors, cats, etc.

Once the cat is removed, you may need to tweak the tune a bit, but the end result would be more power and better gas mileage. Along with a little less weight, a little less heat, a little more sound. Possibly not the sound you want. On cars pulling cats can make it 'raspy' if no resonators are in the system.

[cooldrum_imp]

Very nice mods and touches to your bike! The CB in stock form is an artful design. You took it to even a higher level! I found my CB in Scottsdale and drove it home to Pdx. I should have stopped by for a visit! Russ

[ChipBeck_imp]

There is no such thing as good back pressure. That is a never dying fallacy. An engine is an air pump. Anything that makes it less efficient is bad.

The important tuning part is exhaust pulses, and there are many variables to that- pipe diameter, length, transitions, bends, collectors, cats, etc.

Once the cat is removed, you may need to tweak the tune a bit, but the end result would be more power and better gas mileage. Along with a little less weight, a little less heat, a little more sound. Possibly not the sound you want. On cars pulling cats can make it 'raspy' if no resonators are in the system.

Power,

In a 4-stroke engine I agree IF.....as you say, I were to "tweak the tune a bit" to increase fuel to compensate for the increase in air flow to keep the air/fuel ratio near 14.7 to 1. And as I said in my post my bike ran great from idle to red line as it was. Without the cat it would have been a bit lean which would have required a tune adjustment and I don't have the tools or expertise to accomplish that. If I did then my CB11 would have made a bit more power assuming I got it right. Without changing my tune if cat removal improved airflow enough to take my air/fuel ratio from 14.7 to 1 to 16 to 1 then the result would be less power and rougher operation.

So I decided to stay with the cat and my existing tune which my spark plugs indicate is pretty much spot on for my current setup. Cheers.

Chip