World Superbike Racer
Join Date: Jul 2005
Location: Austin, TX y'all
Thanked 182 Times in 149 Posts
Feedback Score: 12 reviews
Do you have the data sheet on how sportbikes are tested for california emissions? I've never seen that they are tested at cruise for stoic,but I would like to read the data that you found? Also most sportbikes stock run narrowband o2's which are very different then widebands that tune to an afr. Narrowband o2's suck and are not very precise at all.
I've heard of cars tuning leaner at cruise, but they have knock sensors, egt's, wideband o2's, ecu's that will adjust the timing based on these sensors, etc. We have none of that on our bikes. You're tuning for a lean condition hoping things are okay by the seat of your pants. It's not a good idea and you'll save very little gas so why bother and risk it? It doesn't make sense when you don't have any safeguards for a lean condition like cars do. You can't compare apples to oranges. Also our bikes cruise at a much higher rpm then most all cars/trucks/etc.
Stoic isn't something that is super important in tuning other then idle for sportbikes. It's nothing more then a chemical reaction where everything burns. However, that doesn't take all the other variables into account. Such as the fact that in an engine things happen in milliseconds and you don't always have enough time to wait around let things burn and reach stoic. Without that extra time things are too lean, too hot, will knock and cause damage. At idle there is very little load on the engine and you can tune to higher/leaner AFR's like 14.7 (but why even bother if your bike idles fine you're fine), but at cruise you have a load on the engine and it's a very bad idea. You need a richer environment so it will burn cooler, can react in the given time, won't pre-detonate, etc.
Even while cruising stoic can lead to a very hot engine and a lean condition and you have no safeguards on a bike, like you do on a car, to watch out for it. You're guessing with your engine and pretty much for no reason.
Last edited by motomummy; 11-14-2012 at 03:00 AM.