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I could not find anything in the archieves.
How do I tell rich versus lean?

I added a RoadRacing Exhaust to my 01 M900 with PowerCommanderII. I plan to open the airbox and add BMC filter. SInce there is no map for RR exhaust, I will need to play with it myself. If I fail, I will take it to a shop.
After adding the PCII, I notice hesitiation on accelleration and occational hip-up while cruising. Before I added the PCII, RR exhaust only, it "cracked" & "pop"ed on decel. Did I go from lean to rich?

What is my next best step?

THANKS!
 

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Normal spark plugs should be dry and light brown. Rich will be black and usualy powdery, but maybe black and wet. Lean will be white and very burned looking.

If you're using the plugs to re-map, you'll have to check at a variety of engine speeds and throttle clockings. Might be too many set points required to do it properly. But you could do engine chops (hit the kill switch at planned rpms/throttle openings, then pull the plugs) to verify some selected points and assume if they're right, the rest of the map will be.

-Don
 

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The easiest way to find out if you're rich or lean is to compare how it behaves when it's first started to how it behaves when it is fully warmed up. If it's better when the engine is cold, it's rich. If it's better when the engine is hot, it's lean.

Make sure you're testing at a particular engine speed and throttle opening for both cases, and preferably on the same section of road as well.

Much easier than reading plugs.
 

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the empirical way of finding rich/lean is great, but if i was going to do any serious tuning or tweaking id spring for an air-fuel-ratio gauge. the most consistent way to figure out where you're running.

my .02
 

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"Air Fuel Ratio Guage"

Is there something available that doesen't cost Big Bucks & look like it should live in a sound proof room attached to a Mega Bucks Dyno??

I would love to buy on to?
 
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The easiest way to tell rich from lean is indeed by spark plug readings, ie. the whiter the plug the leaner the mixture. One thing is for sure, if you open up the breathing of the engine by using a more free-flowing exhaust and do nothing else the bike will be leaner. The symptoms you list also indicate a lean running condition. You may have gone from way lean to only slightly lean, but I suspect you are still on the lean side of things with your setup. Definitely does not sound rich.
 

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in addition to the gauge, you may need an 02 sensor.

i foudn this rather quickly, LED version lights up depending where you are burning:
You're right, they're all just glorified voltmeters, and all require an external O2 sensor. The monster has a port for fitting an exhaust probe, but I don't know if it's a standard connection. Anyone ever use that nub on the horizontal cylinder header?
Rene Carlos
 

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This answers all my question about rich/lean you guys rock. I'm running lean cold runs like crap/hot she runs better. I checked my spark plugs and i see white stuff on both.
 

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Since you're moving more air, you're making your bike run leaner than it was before by default. After you open up the airbox, you'll be moving that much more air, making yourself run even leaner. (This is not to say that you are definitely on the lean side of the spectrum.) The popping on deceleration is a pretty good indicator of running too lean, along with your description of the hesitation. A good indicator if you're running too rich is to put your hand so you catch the exhaust and smell your hand. If your hand smells like gas, you're running too rich.

All that aside, checking your sparkplugs is the next step. Like others have said, they should be a nice light tan color. If they're black, you're running too rich. If they're white and pitted, you're running too lean.

Good luck!
 
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