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AFR goes down after a few seconds WOT!?

F

FrankTheTank

Member
Lifetime Membership
Im trying to figure out PCV settings on a SBA 800 -2011.
I run a AAEN pipe and PA 12,5 head.
It does the same thing with stock head.

The first 2-4 seconds wot in runs god and sounds good, AFR 12,4-12,6 (sensor 1" from the stock EGT sensor), about 8200rpms and really strong.

But after that, the AFR goes down to 10,9-11,2 and the motor sounds that it has to much load on it. The rpms are still above 7950.
It gets worse the longer the pulls are, and then the AFR goes down faster after a while.
Watertemp under 50 celcius / 122 fahrenheit.

I didnt have the Inovate AFR on it before, but I think in ran better a few days ago and hold rpms better.

Any suggestions?
Heatsoak, fuelpressure, EGT sensor, lean, fat??
 
Put an EGT gauge on it, near the stock one and then report back.... What altitude you at?
 
Try taking some fuel out of it on the 8000-8200rpm.
I think @ full throttle your to rich, slowly pull fuel out on top. Spend a day just tuning afr with ratio and plugs. Just my experence with afr gauge. On my last Cat I tuned for 12.0, but found it ran better @ 11.7-11.9 on long pulls.
 
^^This is good advice. Sounds to me like you're rich at WOT. When tuning carbs, we would usually start out with a 6-8sec run at WOT to see if we were rich, lean, etc on the top end. By the sounds of it your midrange is tuned well, but your topend is rich. It take a few seconds at WOT for the full topend fuel settings to kickin, and in this case, reduce your rpms because you have too much fuel. This is imo.
 
I ride from 400 meters up to 1000 meters.
Premium fuel and premium plug.

I mixed some racegas in it today, just to see what happend.
If it has deto and automaticly gives it more fuel, but nothing happend, no real difference in AFR numbers.

After a long wot pull in deep snow, the AFR goes down to 10,8 and then it dies and I have to back of the throttle.
I just think its strange that the afr goes down the longer the pulls are.

Right now im on small plus numbers on the PC, but if I use the afr to tune it, I need to go to minus numbers at wot.
I think that is strange, from what ive heard, the AAEN needs more fuel then stock.

Can the postition of the sensor be a problem, beacuse of the internal stinger of the AAEN pipe?

Putting an EGT there is a good idea, but I dont have anyone right now
 
Are you running rich because you aren't sucking enough air? Have you done anything to improve airflow into the engine? Is your intake restricted by snow or something else? With the AFR slowly richening up during WOT, I would suspect your intake.
 
Yes air intake might be one thing. Will fix that now!
It hasnt been restricted, but it might not be good enough.

Its already on my to do list, but its hard to find time to fix all the to do when our riding is so good right now!!
 
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