Air Fuel Ratio

Yes, a pipe will change your AFR. Who knows, it may make your AFR better?

Get yourself some sort of tuner that is capable of datalogging. I will not mention names or brands, there are several good ones out there.

Learn how to use it and go from there.

Get it out of your head that 12.5 is best. Your bike will like what it likes and will run best when the AFR is set where the bike wants it. Sorry that is so vague, but it is fact. All bikes and builds are different.

Example:

What "typically" works best for accelleration (WOT) is a lean spike followed by a rich drop in AFR. What afr ratio is that? Your bike will tell you in a datalog.

Sorry this is not what you really wanted to hear. You have a learning curve ahead of you before your bike is running tip top.

Wolv said:

Willy, how about just pointing out what has worked for you. That's all Joe has done.

I do believe, that if you have the tools to measure A/F ratios, you can in fact prove if you are wasting fuel, or pushing meltdown.

I have some of the same hardware as Joe and I bought it for the purpose of KNOWING if I'm tuned safely and as efficient as possible.

I know you tune using pvc pipe on the intake. Do you offer a pvc pipe kit that measures A/F ratios and proves you are in the Safe Zone?

Click to expand...

this has also been covered extensively. A/F Ratios don't prove anything. they might help you guess better. or they may not. all an exhaust sensor tells you is that there is O2 in the exhaust gas. that is not a bad thing. especially with EFI. back in the carb days a Lambda Probe had more meaning. for drag racers it is a valuable tool.

it just blows my mind that some thing BRP/Rotax, one of the largest engine suppiiers on the Planet, can't write a fuel map?? but some hillybilly can make magic with a hundred $ box?

some seem convinced that changing the muffler is a big deal?? its not. it is against the Law because there are Db laws. also there is an EGR effect that lowers some pollutants. if you open the exhaust you get more power and that emmision component is disabled.

the engine sensors are in the intake, not the exhaust, for good reason....that is where it is all happening. if you add too large an exhaust and lose power, you have added too large an exhaust. simple. no fix for stupid.

:beerchug1:

Dont listen to the garbage that mudblogger spews out. He has never tuned anything or monitored anything is out to lunch on 99% of his skewed beliefs. He doesn't understand or has ridden what a tuned engine feels like and runs like. And he doesn't realize that a factory mapping is for a factory engine, along with certain goals of emissions and a 3 year warranty. When one has different goals and different airflow then a completely stock bike, mudblogger just gets overwhelmed and lost.

AFR is a great indication and tuning tool. However, it takes experience to learn and use that info. The best afr for any particular engine range has a lot of variables. The most important thing is just being within an acceptable range for engine safelty.

Currently, your real only concern would be to see what the afr is. Fix the afr at wot as the factory goes too rich for best power. And also look at the range throughout so you don't end up with hot exhaust and melting plastic. As well have an engine that is not unneedingly overheating on you or blowing out your exhaust packing or piston rings early from too much fuel.

Your best bet is to talk to the manufacture of the exhaust or tuner you bought. They actually test things and give you straight answers. They will guide you a lot better than opinions of internet wannabe's.

Willy, as a mechanical engineer, I know what works on paper and "computer models" doesn't always apply to the real world hardware. You, as a long time auto mechanic should know that the stuff in books doesn't always work on the real world hardware.

Case in point, the double rotor Chinhook helicopter - one of the military's work horses DOESN'T FLY ON PAPER. If we only go by what works on paper, then the military would be asking you to develop.. nevermind, no they wouldn't be.

Let me ask you something based on your last post:

"if intake builders for these quads had air flow data it could be more accurate, but it still gives more than just guessing." those are your words, correct?

So what you are saying is that you computer models are close, but could be closer? Why is it so hard for you to undersatnd that BRP gets their maps CLOSE for the OEM hardware .. but when you change something to become NON-OEM it only gets further and further off? Take some of you cam lobe data and change a number or two.. does it throw your entire data out the window? I'm sure the same happens to BRP's model when we change an exhaust and add a different air filter. They can't test everything in advace, can they?

Tell me this, sir, why is it, in the automotive world and now even some motorcycles, they have moved away from the OPEN LOOP system? That means, the throttle body injections are pre determined by a map - given certain input variables, the injections come from a lookup table. The injection happens, and it's just assumed the result is as desired.

They have moved away from that OPEN LOOP system to a CLOSED LOOP system. That means, they pull the injections from a lookup table, and instead of just assuming the result is as desired, they use an O2 sensor to MONITOR the results - and if the results are NOT as desired, things get changed in the system. Closed loop - ya close the loop by MONITORING the results. Ya can NOT monitor the results from the front end, can you?

POINT in case, why do you have to enventually replace the O2 sensors on cars and trucks? If they weren't needed to get keep your vehicle running correctly, then why do they effect the tune when they begin to give false readings? Are you now saying that Rotax knows more about tuning than Ford, GM, Chrysler and EVERY OTHER gas engine manufacturer that has moved to O2 sensor monitoring?

I don't know open loop vs. closed loop from Vtwin as you will likely assume I've been spoon fed. I know it from real world exposure as well as systems control courses in college.

You post on a Open loop system here on Can-Amtalk... you post, and you assume the result you desired happens - and that's that we just believe what you say. Truth is, your open loop system never did any map work for people that can think for themselves and use advanced technology to move forward.