Discussion in 'Tech' started by track wagon, Apr 10, 2018.
When tuning with mr12 what air fuel ratio do you shoot for?
Why would you tune to a different AFR then you normally would?
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I don't know that is why I am asking!
Depends on what the bike wants and makes better power, there is no "perfect" AFR for all conditions. I've seen bikes that made more power at 12.8 to 1 and others that liked 13.1 to 1
Lol, I was wondering myself.
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Ok that makes sense I just didn't want to be shooting for 13:2 and 14:4 is the sweet spot. It that makes sense.
14:4 sounds a little lean It will be in the ballpark of where it makes best power on pump fuel maybe just a few tenths difference and some will be the same. You won't know unless you experiment.
I probably wouldn't lean it out that much!
I figured, that's why the smiley.
MR12 will give you best power probably around 12.8-13.1. Ignition timing affects it. The power comes from the oxygenates in the mix and if you lean it out, there’s less of those catalysts to burn. Your dyno tuner should move the target around for optimized power output.
Lambda, lambda, lambda. Stop with AFR.
Because not all race fuels uses "pump gas" stoichiometric ratings. From what I have seen, most of the tuning AFR ranges given out on the internet have been based on and assumes pump gas stoich rating (14.7 parts of air to 1 part of fuel).
If your race fuel uses a different stoich rating, you need to run the math to convert to target AFR (because most AFR gauges are calibrated to pump gas stoich rating), or like Odilup suggests, tune using Lambda.
From VP's wesbite:
MR12's Stochi rating = 13.13 to 1
Pump gas = 14.7 to 1
A competent and experienced tuner should know this and will know what ranges to experiment with when tuning your engine setup. Like RM said, there's no set number and that number will also change depending on load/engine RPM as well.
As RM alludes to, ignition timing is probably where you will see your biggest "tuning" gain with MR12. Get the AFR between the goalposts and then start tweaking the timing. If you don't play with timing you could be leaving a nice chunk of power on the table.
Playing with the timing leaves lots of room for dentation does it not? I have seen a motor do that..... and it wasn't good.
How do you change the ignition timing on a 2006 SV650? or can you with electronics? Or does it have to be inside the motor? I am not an engine builder or tuner obviously..... I just know with the newer stuff you can do it via electronics but I don't know how it work on older bikes.
Dynojet ignition module if running a PCIII. PCV, or the like.
(Detonation) Assuming you are giving it too much timing, it's possible. And who says you would be advancing the timing? Dynojet or ECU flash for changing the timing on a SV. You could also install an offset flywheel key, but I like the keyboard method more better.
No one did I just didn't know if the pcv was able to do that on a 2006 model. I found a good tuner I will post some numbers once it is done.
I have done some research and this couldn't be more correct. Lambda is always the same no matter what fuel is in the bike.
I'll echo a few points here. My bike is tuned for MR12 and pump fuel and the MR12 map is about 12% richer which aligns with the stoic difference between the two fuels. This would mean they are tuned to the same lambda.
Also - with MR12 you remove spark, you don't add it. I run 5 degrees less advance with MR12.
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