a/f ratio wont read on dyno

[Tbax]

Hello all. Been to two different shops to get the af checked and both read off the chart rich (below 10). First some bike background. Shimmed oil pump, dial a boost set at 15psi, 0-5k pot set at 2k for roughly 10 percent increase in fuel, afpr set at 40 psi, tps set accordingly, stock internals. Engine is in great shape with 12000 miles. Correct compression, no smoking etc. As mentioned, the bike reads way rich all the way through the pull but the plugs read a beautiful light tan. I was wondering if it could be my exhaust since it is just a dump pipe? Maybe the sniffer doesn't read correctly with that setup? Bike pulled 107 hp on one dyno and 103 hp on the other. Wasn't looking for my zx14 numbers but was at least hoping to achieve 120hp. Any answers, thoughts, suggestions would be greatly appreciated!!

[dazbo]

if the exhaust sniffer was picking up outside air i think i would expect it to read leaner than actual rather than richer ???
you could try a temporary extension to the dump pipe to be certain.
kawasaki did a good job of mapping the bike so maybe race mode plus extra fuel pressure is a bit too rich.
you could try weakening it off a bit by lowering pressure to standard or race mode pot to minimum (1.2kohm) and see if you get an increase in afr and power.
or maybe even try a pull with standard boost and no race mode to see what afr readings it gets you.
its hard to read plug colour without doing a plug chop(accelerate hard against a load,say uphill and killing the engine) as idle mixture will colour the plugs but not give you a read from high load, but you dont want to try that with a turbo as a fast spinning turbo and no oil pressure is not a great idea!!!!

[georgew4714]

I also have a short dump pipe and was able to get readings . Surprised the shops equipment doesn't record under 10 . Did you ask the operators if there equipment is capable of reading below 10 or is the bike causing this ?

On this run i had my pot adjusted to full rich (5k) and my readings were low 9s .

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[Tbax]

Thanks for the responses. Correction in my post. If you measure the pot itself out of circuit it is at 4k. Anything less than 3.2k it did not like,lost power and you could tell it was running lean but did not cut off. Both dyno machines would not read lower than 10 afr. Even on the seemingly lean run it never registered. I did play it safe and ran 110 octane mixed with 91 roughly 50/50. Wondering if that could have thrown the sniffer off. The bike has great manners around town and never fouls plugs. At 107 I'm not to far off your mark, maybe in the real world that's just where it lands. My graph looks way different than yours however. I will try and post one but roughly 5000 to 7500 is violent going from little boost to 15psi in that range and then flattens out to 10000 rpms. The graph has quite the slope and me wishing for a BOV during the inevitable wheelie that follows the curve. I would call it fun but with the increasing rareness of these bikes it makes me generally play in second where wheelies are less likely and my overall well being stays in check.

[Tbax]

The above dyno I inserted was the second one we tried at 3.4k which lost power. Thanks again for all the input. At 30 bucks a session, I try not to burn to much of their time up.

[georgew4714]

Im definitely no dyno expert , other people here have much more experience.

Was the 110 you used ...leaded ? Im pretty sure the sniffers dont work right with leaded fuel . Maybe best to run just straight 93 and just moniter boost levels . I run 15 psi on straight 93 and havent had a problem . Just be careful and moniter boost levels . At 15 your almost on the edge of safe and not safe .

Also , it would give you more room to analyze and compare data if they logged HP from RPM not MPH . MPH is kindof a useless statistic . You reference a power spike between 5 and 7k and a flattening out at 10 but your graph you posted shows .

[Lorcan]

You won't need the resistor AND increased fuel pressure at stock cc, in fact you probably won't need either of them. The bike is mapped pretty well to 15psi as it is, even with an open exhaust and an air filter. You will need race mode though, which in itself will richen up the fuelling. Remove the resistor, and try a run at stock fuel pressure. Use ordinary pump gas. Race fuels have variable specific gravities (density) so will throw readings off, and dyno places usually won't accept leaded fuels as it kills the sensor after a while. They will sometimes let you bring your own sensor, but you don't need race fuel at 15psi.