PC necessary??? Improved airflow, engine longevity

[RockerGuy]

Yes. This, and getting better range and mileage (and the ability to hook up a quick-shifter) were the motivations for getting a Power Commander for this bike. No real difference in power output - full throttle calibration was okay, it was just the part throttle area that's out to lunch.

A good many tuners don't know how to set part-throttle up properly, and most people who buy a PowerCommander won't pay the true labour cost for doing it. Gotta do it yourself.

Makes u wonder how it passes emissions in California

[dricked]

Where's the cat on an 04 zx10? I thought 06 was the first year for that.

[Brian P]

Makes u wonder how it passes emissions in California

Simple; North American emission standards for motorcycles - even in California - aren't very stringent. And, the stock emission control strategy is to run the engine rich and then let extra air into the exhaust to burn off the HC and CO in the catalyst. Although it "works", it is a crappy strategy that results in high fuel consumption (and oil dilution, and oil washed off the cylinder walls). But it saves the manufacturer a $35 oxygen sensor and it allows the ECU calibration to be simpler so it saved a bunch of engineers a couple weeks of calbration time ...

The later models in Europe, which had to meet Euro 3, got that oxygen sensor, but they still run rich and use air-suction to sort it out by the catalyst, just not as badly.

Secondary air-injection systems went the way of the dodo in cars years ago. Ya don't run the engine rich at part-load cruise. Ya run the engine on the right air/fuel mixture to begin with.

Where's the cat on an 04 zx10? I thought 06 was the first year for that.

It's inside the muffler.

[sixstring]

Ususally a tad lean in my experience.

Which bike? Most manufacturers run their bikes rich because, among other reasons a rich engine is safer than a lean engine. Therefore aftermarket pipe and air filter usually makes a little more ower with no tuning neccessary because it leans out the mixture closer to something that is proper.

My ZX7 for example (which is a rather extreme example) came with 170/180 main jets!!!!!! MADNESS!!! A CBR900 for contrast came with (I believe) 120 main jets. Even with a full ehxuast the 7 still ran rich.

[casacrow]

It's crazy how far bikes can be off. I usually find lean on the bottom and at less than half throttle, then a little rich up top.

My ZX6 was just damn lean everywhere. Even up top. Extremely lean off idle and the lack of power there was very noticeable. Must be an emissions thing, likely why all these pilot screws are sealed up on carbs. It's good now with new needles and mains. Slightly rich up top, but I like it that way, allows for a lil more ignition advance, some cooling effect, and peace of mind.

I've got a 675 that runs a bit rich halfway through the RPM's and open throttle. I'm cool with that. Peace of mind thing again, and I'm running about +10* timing above 10k. It was very lean off idle as well. Caused for a very lurchy bike at very slow speed in street conditions. A lil more fuel solved this. There was also a lean spot around 3500-4000k. I'm not sure if this is an emission thing, or possibly it's what the motor wants at the RPM/Airbox/exhaust/ combo. I've never noticed fuel smelling oil. I have some prepaid oil sample kits that I need to use up. Might fire off a sample this summer to see if I'm getting any wash down.

For both bikes above, even though AF meter is saying slightly rich at higher RPM's, plugs look great.