I have a 2011 RKC with Vance/Hines mufflers and a SE air filter. I purchased a SEPST and reflashed with a standard map. I then did about 8-10 "Smart Tune" runs and reflashed again. I've put about 1000 miles on it since then, and my plugs are still pretty white...assuming I'm still running pretty lean.

Is there an easy way, or can anyone explain to me how I would richen up the mixture using the SEPST? Can I just change the AFR values to a lower number and reflash? I'm far from an expert at using the tuner, hence why I ask if there's an easy way to do it. I hate to spend the money to get it dynoed.

Thanks.

 

Sorry I got no experience with the SEPST, but plenty of experience tuning by O2 feedback. If I understand correctly the street tuner has limited capability which keeps it within EPA compliance, so you probably wont get rid of the white plug condition. I have seen white plugs with a cruise range of 13.8, just not a good indicator of your tune condition in an EFI. How's the bike running? Do you just want to add more fuel because your plugs are white? I hate to spend money on a dyno too, thats why I got an O2 datalogging system from DTT. You simply must have some type of O2 feedback to tune accurately, your choices are; put it on a dyno with a sniffer, add an O2 datalogger, or settle for a canned map and accept not knowing you actual tune condition. You spend more time in the cruise range than anywhere else, and that has the greatest influence on the apperance of your plugs. If you want brown/tan plugs you need to set your cruise to high 12's to low 13's.

 

If I could have got to you before the SEPST I would have recommended going to a VIED. I was able to clear up a large part of my chalky plugs with it. Im running Jackpots with a stock system & AC (KN inside it). Plugs were a tad chalky before I took the Cat out but increased after. The VIED is variable allowing me to adjust each cylinder individually to achieve the desired coloring.

 

plug reading has no application with modern efi systems.

the data gathered by peering at a plug means nothing unless it is covered with soot or oil which might reveal a physical fault

if you want to know what is occurring and under what conditions tap into the o2 sensors.

mike

 

Why does it have no application? The ecu controls the fueling and other parameters, but the plug doesn't know that. It simply fires when told to by the ecu. Hence if it's running rich the plug will still be black, running lean it will still be white, etc.

I don't understand why you think it has no bearing. Please explain.

 

I'm with you...seems like plug color is a product of fuel/air mixture regardless of whether that's controlled by EFI or a carb.

 

I'm saying...........

 

Mike has the right idea but his response may be a bit misleading...the modern EFI systems control fuel/air mixtures a lot better then the old points and condenser era.

With the more modern fuels, ignition, and injection systems, "reading" plugs has become much more difficult.

By the time the plugs show much of a tendency towards being rich or lean, the EFI is way out of whack.

There are far better and more reliable methods to determine if a particular motor is running outside of its design parameters. I would not rely on the now aged method of reading plugs.

But if you want to quickly richen the mixture of a cylinder without any cost, simply decrease the plug gap...that will keep it from firing as hot as it could and reduce the cylinder's efficiency.

 

My auto mechanic and I were having this discussion today. I guess back in the carb and points days they could read the plugs with just one pass down the track,then adjust the jets,in search of better run times. He stated that due to today's fuels and each stations different additive package it's far more difficult,unless you run only one brand of fuel,establish a baseline,then multiple runs,pulling the plugs after each run,comparing them.
From what he said most every plug he pulls out of cars today are white and ashy. He said it's the additives.
With a grain of salt gents

 

We're not talking about tweaking a carburetor anymore, we are electronically manipulating the map in an EFI system. A carb basically delivers the same amount of fuel, or two amounts of fuel (2 jets) across the entire RPM operating range, but with EFI, fuel delivery is practically infinitely adjustable, the map maximizes efficiency of both power and economy as AF transitions from more to less, and less to more fuel as needed across the RPM range, based on accel/decell, MAP, IAC, RPM range, throttle position. What a lot of folks forget when talking AF ratio, is the fact that it transitions across the map with EFI, you may have a cruise range target AF set at 14.6, 14.3, 13.8 or whatever, but the other areas outside the cruise range of your map have targets also, typically richer than cruise, and progressively richer as throttle position and RPM increase. Generally an engine spends a majority of its running time in the cruise range, or leanest sector, which has the most effect on the color of the plugs. Depending on the values across the entire map, and operating conditions, plugs could look about the same with a cruise AF anywhere from mid 13s to mid 15s, that alone is a 2 point spread, about a 13% variance, then add the error of individual interpretation. EFI gives us the ability to precisely meter fuel at thousands of points across the map, and adjustability to .1 AF values. Barring merely identifying that an extreme condition exists, plug reading in EFI offers no useable feedback to tune by. Ask a dyno tuner to tune your EFI bike without the sniffer hooked up, and just looking at the color of the plugs. True you can look at the plug and see that it is white, tan, or black, but that doesn’t quantify the degree of the condition. Some type of O2 feedback is the only solution to verify tune condition and assess corrections to achieve a desirable condition. That’s just my opinion as someone who has used O2 datalogging, to successfully tune for many different changes over the past few years, and observed the unpredictable relationship between plug color and tune.