AFR "Safe Zone?"

josmas

.020 Over
Joined
Feb 11, 2012
Messages
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Location
New Hampshire, USA
One more question on tuning…
This is probably directed at Hans, but maybe someone else can chime in or even benefit from the the answer.

Is there an AFR "safe zone"?
Can we lean out all the way to 14.7 and be safe? Lean = heat, right?
And, how rich can we run? Too rich will foul plugs?

Just trying to understand all this…
 
Yea I want to know the same thing. I feel that mine is running too rich.

What about it people?
 
When I was sussing out the PCV I asked several dyno tuners and the general consessis was do not go higher than 14.7 and lower than 12.5 so I have basically stuck in side that range, but I have found the that while 14.7 for cruising at speed limit speeds it was running a tad hotter and have dropped it to 14.5 so as to keep it running cooler I am finding that it is still burning a nice dark grey pipe and responding to a roll on. As I have said I am still experimenting with this a new richer version which only go's to 14.2 I was also told that 13.2 was a good compromise AFR but I found it was neither great for fuel economy or power just a middle non exciting level
 
I'm with you, Hans. I'm not sure I would lean it out much more than 14.5 or 14.7 if she's starting to heat up.

For what it's worth, I found this post by Forchetto on TriumphRat.com (I want to give the guy credit (or blame) as appropriate).


Most of the time we ride with just 10% or little more throttle opening.

Here's a list of Air/fuel ratios:

9.0:1 BLACK SMOKE (NO POWER)

11.5:1 RICH BEST TORQUE @ WOT

12.2:1 SAFE BEST POWER @ WOT

13.3:1 LEAN BEST TORQUE @ WOT

14.6:1 Stoichiometric AFR ( CHEMICALLY CORRECT )

15.5:1 LEAN CRUISE

16.5:1 BEST FUEL ECONOMY

18.0:1 CARBURETED LEAN LIMIT

22.0:1 EFI LEAN LIMIT
 
just to clarify I was told running richer than 12.5 would be basically pumping fuel out of exhaust in other word a very high risk of flooding and when I said my bike was getting a bit hot as you do when a bit lean I was told that 14.7 was about as lean as you would want to run for any sustained time as much leaner over an extended time would risk burning valves etc and that is why in original ma PCV map I had it 14.5 and now the new one I am running 12.2, when I can afford it I will go up to Canberra and run it on the dyno up there to see how it shapes up but I know it definitely feels great
 
Hans when you run her on the dyno have the guy stick a sniffer up the pipe so you can compare the accuracy of the wide band O2 sensor verses the multi spectrum annylyzer on the dyno. I am currious how accurate the Auto tune sensor is.

One should also consider the differences in octane bought at various stations thru a trip for safety I woul dnot go leaner then the 14.57 that is programmed in the ecu. I like the 14.5 for lean at the most. But On the Falcon I will not run it that lean in fact I will not go any leaner the 14.0 and try to stay at 13.8 but then fuel is cheaper the engine parts. In my open throttle areas I do run lower but try to stay above 12.5 unless boost is high and timing is right. Timing pays a big part in all this. Its not just the A/F its everything put together to make a efficient burn.
 
It sounds like 12.5 − 14.5 is pretty safe.

The list I posted lists 15.5 "Lean Cruise." It sounds like that is a bad idea!
 
I am surprised that you even go near 14 with the forced induction
josmas said:
It sounds like 12.5 − 14.5 is pretty safe.

The list I posted lists 15.5 "Lean Cruise." It sounds like that is a bad idea!
Click to expand...
to be honest feeling the extra heat comming of the headers at 14.7 I think 15.5 is like writing a death wish for the motor!!
 
josmas said:
It sounds like 12.5 − 14.5 is pretty safe.

The list I posted lists 15.5 "Lean Cruise." It sounds like that is a bad idea!
Click to expand...
I agree especially with such a small amount of coolant to keep the engine cool. Of course changing the pistons liners is a breeze the valves are pricey. but all this can be done while the engine is in the bike. but changing things like the crank is where you have to take the engine out. working on the tranny sucks for the same reason.

All O2 sensors are not 100% acurate and I would suspect the Triumph one is not either so why gamble. Even the air temp sensor is off by 17 degrees so the ecu leans out the bike as it is with just that temp difference. I bet you would not squeeze to many more mpg at 15.5 especially since its hard to stay out of the throttle
 
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