I have track bike 2009 RR
I installed Bazzaz Z-Fi , Z-AFM , Ten Kate intake (direct air flow) and leovince full exhaust
Bazzaz stock target AFR set to 13.0 i didnt feel performance increase
What AFR i must set for track bike
stoic is 14.7 but it has NOTHING to do with tuning. The person that got people to believe that has something to do with tuning read wikipedia and didn't fully understand it. You can tune around stoic at idle with pretty much zero load on the engine, but the minute you get a load on it you better give it a lot more fuel then stoic.
13.0 or 13.2 is what most people tune a bike to if you want good power and a safe tune that won't damage the engine over time. As you get in the lower rpm's you can lean it a tad if you want, but you will barely gain any mileage for fuel economy and remember you're just guessing on what is actually safe. IMO just tune to 13.0 or 13.2 across the bandwith and you'll have good power and a safe tune.
Even while cruising you have a load on the engine. With anything say over 50% throttle you want to be in the 13.0 and 13.2 area. While cruising you could go to say 13.7 but over that and you're getting into the area that is too lean. Never around 14.0 ever as it's too lean unless you're at idle. knock, detonation, heat, etc.
This entire stoic thing people need to 100% forget as it doesn't apply to engine unless they are at idle. With load on the engine EVERYTHING changes.
So around cruising area you could do up to 13.7 if you wanted, but imo it's just not worht the trouble. I tune to 13.2 across the board and call it a day.
It's not just bad for the bike when you get over a set AFR, but you'll also make less power and more heat when you get too lean.
13 to 1 a\f ratio is usually the best for power, the wide-band a\f sensors that come with the Bazzaz i have heard are no always accurate. You could confirm things with a good dyno tune with exhaust gas analyzer. The reason the manufactures try to keep the a\f ratio close to 14.7 to 1 is emissions. The catalytic converter works best to reduce HC, CO and NOx at that ratio. I don't no at which point, but a steady diet of rich mixtures ( possibly 12.5 to 1 ? or richer ) will soon ruin the cat, even melting it down and plugging it. Of course most of us lose the cat and we can tune to what ever ratio gives us the best power.
Last edited by tuck and roll; 11-13-2012 at 10:07 PM.
Reason: more info
The manufacturers do not try and keep it near 14.7. They would blow the engine in time. Nobody tries to tune to 14.7. The only place you should ever see over 14.0 is around idle and that is about normal. This entire 14.7 thing needs to be forgotten. In fact at high rpm's most manufacturers have it a bit too rich to ensure the engine survives their warranty period.
I agree these engines come a bit rich on the top end to keep them alive, but i don't know how you figure these engines are going to blow at 14.7 to 1 at cruise. The california model with O2 sensor feedback system is designed to do just that, to keep the emissions low, and the cat working at it's best. If they ran at 13 to 1 during cruise, they wouldn't pass the california emissions.
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.
Mummy man, i think we agree on a lot of this topic and the original starter of this tread got his question answerd. We just have a slight differance of opinion on how much a/f ratio these engines can take at different conditions. And i'm ok with that. I'd love to own a dyno and spend 100's of hours experimenting. As for my built engine , i will be sending it my dyno guy, telling him to tune for max power and a smooth transition from off throttle, no guessing here.
I would agree. Make sure whoever tuned it gets you the AFR read out on the dyno sheet. Sounds dumb, but I'm kinda shocked how many people get a dyno tune and just get the hp/tq printouts. If the same guys is building your engine I'm sure you'll get the AFR with the power data though.
what I learned from a tuning class is that the difference in power from running 10-1 vs 12-1 is not that huge of a difference in power. ignition timing plays a huge role, after A/F is sorted. everyone thinks tuning is just messing with fuel ratios, and it's a very narrow view of fuel injection tuning.
to answer the OP's question, there is no perfect "track" or street AFR, you gotta give the engine what it needs. and don't worry about the seat of the pants feel, all that money you spent really doesn't net you much noticeable HP. For a track bike you should want smooth, consistent, and reliable power.