Optimum Air-Fuel ?

TurboSN95

Registered
Whats up everyone,

I'm thinking about taking my Busa to the dyno, just to see what its making for power and air-fuel. I am wondering what the optimum air-fuel should be, I tried searching but didn't really see anything specific. My bike is stock, except for:

BMC Street filter
Yoshi RS3 slip on's.
GI-Pro with TRE.

My friends were riding behind me and said that my bike stinks, like its really rich, and the ends of the pipes are black.... So, I want to see where its at, and if its way off, I'll throw a Power Commander on it and get it tuned. So if someone could tell me where the air-fueld "should" be, I would really appreciate it.

Also, I read on here that most people do 4th gear pulls, and that its ok to do an "all-gear" pull. Is that correct as well? I was thinking of doing the following runs, since I think I will get about 4 pulls.

BMC filter/RS3's/GI Pro turned on
Stock filter/RS3's/GI Pro turned on
Filter that makes more power/RS3's/GI Pro turned off

Whichever combo gets me the best power, then i'll do an all-gear run. Sound ok??? Or is it safe to assume the BMC street filter will get me the better runs?
 
12.5-13.1 is where I like on NA bikes,and depends on rider style.Some guys are hiway guys,some street/strip and some all street or all strip.4th gear then do all gear after done,hp/torque should step on each gear change.
 
Best off to retune to where the bike makes Best Power - For the cruise operation, I'd tune to the amount of fuel that makes the engine run smoothest under about a 10HP load. (neh AFR for many different reasons)

There is no "magic" AFR number - each bike is potentially different in what it wants - so - it's best to start knowing that "optimal AFR" number is variable and go right to tuning for Best Power.

If the place that you are thinking about using can't or won't tune to Best Power, then, find a more experienced dyno guy -

That help much?

Marc
 
I like to be around the range of 4.5% CO, 100ppm HC, 1000ppm NOx. Works well for me... It may not be Max power for you though... Every bike is a lil different.

It sounds like you have a nice tame street setup (nothing razy with N2O, cams, etc) so you can keep things on the leaner side (say 13.2 a/f ratio) for good mileage and still have good power. just a thought
 
Yep generally, you'll get Best Power at 4% to about 5% on a stock pistoned Busa.

Should be tuned to Best Power and then look at CO2%, HC ppm, CO2% and residual O2% - and based on the exhaust gas multigas compositions, you can diagnose additional avenues of things that you might change to improve power (after you've got the fuel correct for best power) - That's the neat advanced beyond "AFR tuning" multigas EGA dyno trick -
<wink!>
Marc
 
Yep generally, you'll get Best Power at 4% to about 5% on a stock pistoned Busa.

Should be tuned to Best Power and then look at CO2%, HC ppm, CO2% and residual O2% - and based on the exhaust gas multigas compositions, you can diagnose additional avenues of things that you might change to improve power (after you've got the fuel correct for best power) - That's the neat advanced beyond "AFR tuning" multigas EGA dyno trick -
<wink!>  
Marc
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 helps with the ignition tuning as well... I just luv having a little more than just a/f to play with! I have to admit that I still have a bit to learn about when it comes to 02% and what it's food for...
 
I think I understanding car tuning pretty good (not a tuner just understand what the tuner is doing) but not Bikes. I'm assuming that they are similar in nature, not sure? I know setting the timing is critical in making power and determining how lean you can get your air/fuel ratios. I know octane is crtical in determining how agressive you can be with timing advance before detonation occurs. So i don't think it is a correct statement that you tune to max power because you can lean it out even more and make more power but you could be on the verge of detonation once the temp changes or you change fuel. Does the power commander 3 allow the tuner to change the timing maps? If not the question becomes what is the proper air/fuel ratios for an NA bike with the stock timing map and 91 octane gas. Mods help with increasing power but does not dictate proper air/fuel ratios, timing and fuel (octane) dictate what the air/fuels should be before detonation.
 
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