Busa runs WAYYY stronger some days than others....

[The Big Red One]

Ever since new I've noticed my first gen busa runs WAYYY better some days than others. I ride around 4500-8000 ft in elevation. Its always been soft in the acceleration department from the elevation. But some days it'll run like a raped ape and others it just seems to sit there when I twist the throttle. Last night I went for a ride up to an 8000 ft peak than came back down to 4500 feet. After I came back down with an empty tank at night it wouldn't lift the front in first under power. After I shut it off and filled it up at a 7-11, then started it back up, with a full tank I couldn't keep the front end down under power in 1st or 2nd. It was such a change I had to re-adjust my throttle control, it literally felt like it gained 30hp....huge huge huge diff

Its low miles and runs perfect...never had any probs with it. I've always just figured the elevation was killing alot of power. But last night it ran stronger by FAR than its ever ran. Shutting it off and turning it back on must of reset the sensors after coming down so much in elevation. What could change the performance so much? It runs perfect so its not any fuel/spark probs. And I've never had any codes or warning lights of any kind. I wonder if the ecu is retarding the timing something ridiculous? A sensor malfunctioning somewhere? Or if I even have a prob at all? After last night I know it has the potential to run strong at my elevation....I just need to figure out why sometimes it does and sometimes it doesn't?

 

[bstamper]

Going from 4500 to 8000 ft then back down...maybe the bike was being forced to change the a/f ratio or something and had not fully learned the right settings when you got back down. When you shut the bike off and turned it back on it re-learned things? Just a complete guess and I have no proof or fact to back it up.

 

[Blazing-Saddle]

Mine will run stronger in the cool morning air than in the midday heat here in FL. I'm guessing the cool air is denser and packs a better charge. My mistress is stock except for Yosh slip-ons and a TRE..

 

[The Big Red One]

Mine will run stronger in the cool morning air than in the midday heat here in FL. I'm guessing the cool air is denser and packs a better charge. My mistress is stock except for Yosh slip-ons and a TRE..

My busa's always seemed to be down on power from new, and the power's seemed to be inconsistent. Some days stronger...some days weaker. It's always ran like a top tho...not a single hiccup ever and no codes. And the power does fluctuate some with the weather. But last night when I shut it off for gas, then started it back up it wasn't a little change...it was like it went from running on 3 cylinders to 4. Or like I just got off an old 600 onto a busa. Or prolly like going from mode C on an 08 to mode A. The diff was HUGE. Thats the way the bike SHOULD run...and that what I expected when I first got it.  Its never ran like that before. The only thing I did diff on yesterdays ride was I kept the r's up and ran her hard most of the ride (almost a full tank of hotrodding  

 )....where normally there's more cruising and less r's. I really think I've had a bad sensor somewhere from new.
I just hope it keeps running this good, cause I've been seriously considering selling it. Maybe it decided to do right so it could stay  

 Its the only busa I've ever rode, and honestly I thought it was kinda a dog up until last night. My 14 would normally destroy it in anything that remotely resembled a test of acceleration...but last night it would have given the old 14 ALL it could have handled and then some  

 

 

 maybe there's hope for the old girl yet  

 

[TheAtomicAss]

Even if it runs reliably, it might still need tuning for the altitude. But for the more immediate problem, did you get a loud WOOSH when you opened the tank? If so, you may want to check the tank vent line.

And what octane of gas are you putting in? You really want to run as low an octane as you can get at those elevations.

 

[busajack2]

Shutting it off and turning it back on must of reset the sensors after coming down so much in elevation. ----You answered your own question. The barametric pressure sensor takes a reading at start up and tells the ECU what alt.(,barametric pressure) the bike is at.The ECU then adjusts for that pressure. Something the old carbs can't do.

 

[Revvv]

These bikes don't have a closed loop system. They have no way of knowing what the air/fuel ratio is. When you tune your bike it is done with a particular program that builds an air / fuel map. This map does not change, it gives the same amount of fuel every time you twist the throttle.

Here's the tricky part; when the air changes temp, or altitude, air either increases or decreases in density. A more dense air mixture will burn hotter producing more power. In extreme situations you can run lean.

When you first fuel your tank, normally you are putting cold fuel into your tank. Guess what; cold fuel leads to a cooler air / fuel temp which in turn provides a dense air situation that burns hotter and makes power.

Oxygenated fuels are great for a mild boost in power. Because the fuel is already impregnated with oxygen molecules, the fuel mist / distribution is refined and can burn better. Guess what; more power.

If you can make a larger explosion within the cylinder you will gain horsepower.

 

[tegbusa]

I always feel the difference after I fill up the tank.

 

[Revolution]

and i always feel stupid after reading these edumicated post

good read fellas, thanks

 

[Wag]

Whenever I wash and wax my bike, it runs better.

Of course, that's because the fast color shines through more and makes it faster.

--Wag--

 

[JR'S BUSA]

and i always feel stupid after reading these edumicated post  

good read fellas, thanks

 

[BusaCruise]

one other consideration is that as more and more stations begin to use ethanol...that too will affect the power/mileage issue.
there may be significant changes between different gas stations as well.

 

[SHADiGUY1]

wag must have the Red 07 busa!

 

[The Big Red One]

These bikes don't have a closed loop system. They have no way of knowing what the air/fuel ratio is. When you tune your bike it is done with a particular program that builds an air / fuel map. This map does not change, it gives the same amount of fuel every time you twist the throttle.

Here's the tricky part; when the air changes temp, or altitude,  air either increases or decreases in density. A more dense air mixture will burn hotter producing more power. In extreme situations you can run lean.

When you first fuel your tank, normally you are putting cold fuel into your tank. Guess what; cold fuel leads to a cooler air / fuel temp which in turn provides a dense air situation that burns hotter and makes power.

Oxygenated fuels are great for a mild boost in power. Because the fuel is already impregnated with oxygen molecules, the fuel mist / distribution is refined and can burn better. Guess what; more power.

If you can make a larger explosion within the cylinder you will gain horsepower.

Thanks Revv and everybody else

I guess you're never too old to learn something new

I think between the elevation changes in my area, the unpredictable weather/temps, and california oxygenated fuels, that prolly explains most of the diff in behavior of my bike. I'm gonna check the tank for proper breathing...and maybe a few other things, but I think you guys prolly covered most of the reasons already. It does seem like the grade of gas and where I buy it makes a diff in performance as well

 

[dbf82]

Our weather sux here in South Dakota, so I haven't been able to tell how the biker responds to different weather

 

[mikev7]

I just want to say that my busa is so fast in summer or winter, high or low altitude.. When i open it up and run through the gears it wants to come off the wheels. I have consistently beaten my homeys 06 zx14 on it. 07 bus..