Combustion analyser dyno related - SV650.org

18-01-07, 08:35 PM

I've got this handy combustion analyser from work, measures o2, Co2 and Co. Question is, can I use it to measure how my SV's exhaust products?
I mean I use a very cheap dyno shop, they don't have one and for £10 they're no likely to waste their o2 sensor on you. So I figure I'll go along to their place get the SV up on the roller and then pop the analyser into the zorst.
Will my SV be stoichiometric or not?

18-01-07, 10:12 PM

Will it be stoichiometric? Not even close! (and neither would you want it to be...)

19-01-07, 04:42 PM

What do you know?

20-01-07, 06:42 PM

I'm not sure what your reply meant, but I will assume you are asking for clarification.

As you no doubt know already, stoichiometric is the 14.7:1 air:fuel mixture where there is complete combustion.

When part throttle cruising, the oxygen sensors in cars allow the ECU to constantly adjust the fuelling in order to hover around this ratio, and the result it good economy. When you floor the accelerator in the car, the ECU switches to a richer mixture and ignores the oxygen sensor because oxygen sensors can't react fast enough, and maximum power is not created at stoichiometric anyway, it is created somewhere between 11:1 and 13:7:1 depending on the vehicle/revs/conditions.

Why doesn't this apply to bikes, and your bike specifically on a dyno run?
- There are only one or two bikes on the market with oxygen sensors, and SV certainly isn't one of them.
- On a dyno power run with the throttle wide open, stoichiometric is the last thing you want unless you want to melt your valves. If your oxygen sensor is a wide-band variant then you might see somewhere between 12.5:1 and 13.5:1 if your engine is in good tune.

18-01-07, 08:35 PM	#1
Razor Guest Posts: n/a	Combustion analyser dyno related I've got this handy combustion analyser from work, measures o2, Co2 and Co. Question is, can I use it to measure how my SV's exhaust products? I mean I use a very cheap dyno shop, they don't have one and for £10 they're no likely to waste their o2 sensor on you. So I figure I'll go along to their place get the SV up on the roller and then pop the analyser into the zorst. Will my SV be stoichiometric or not?

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18-01-07, 10:12 PM	#2
sdusk Guest Posts: n/a	Will it be stoichiometric? Not even close! (and neither would you want it to be...)

19-01-07, 04:42 PM	#3
Razor Guest Posts: n/a	What do you know?

20-01-07, 06:42 PM	#4
sdusk Guest Posts: n/a	I'm not sure what your reply meant, but I will assume you are asking for clarification. As you no doubt know already, stoichiometric is the 14.7:1 air:fuel mixture where there is complete combustion. When part throttle cruising, the oxygen sensors in cars allow the ECU to constantly adjust the fuelling in order to hover around this ratio, and the result it good economy. When you floor the accelerator in the car, the ECU switches to a richer mixture and ignores the oxygen sensor because oxygen sensors can't react fast enough, and maximum power is not created at stoichiometric anyway, it is created somewhere between 11:1 and 13:7:1 depending on the vehicle/revs/conditions. Why doesn't this apply to bikes, and your bike specifically on a dyno run? - There are only one or two bikes on the market with oxygen sensors, and SV certainly isn't one of them. - On a dyno power run with the throttle wide open, stoichiometric is the last thing you want unless you want to melt your valves. If your oxygen sensor is a wide-band variant then you might see somewhere between 12.5:1 and 13.5:1 if your engine is in good tune.