Lean or Rich on PCIII - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 4 (permalink) Old 08-25-2002, 07:32 PM Thread Starter
Join Date: Jan 2002
Posts: 174
Lean or Rich on PCIII

I've had my PCIII for my F4i for about a month now. While I have noticed some significant crispness in the throttle after installing it, I have just a couple of questions I thought maybe you guys could gimme a had with.

First off, I have an M4 hi-mount sport slip on. I haven't found any maps ANYWHERE on the net or around at any shops for it. So I just naturally picked another pipe that had a 'similar' bend in the pipe. That being the Devil hi-mount. Seems to work just fine and I know the only thing I could be lacking in is just a smidge of performance, but I'm not currently running her at the track so I'm not much worried about it. Anybody have or know of a map for the M4 hi-mount sport???

Second question is about the settings. I asked the mechanic at the place where I bought the bike (whom, btw, I trust very much with my bike and questions about it) whether I should be running lean or rich on the settings. He told me that I should be running a bit on the lean side. Just HOW lean he didn't say. So I set it up so that it was sounded like it was just about to die in idle on the LOW rpm setting then went one setting UP. Then set the mid range for just about the same. My question is this: Doesn't this more or less contradict having a jet kit on a carb bike? Isn't the purpose of getting a jet kit to richen the amount of fuel that gets combusted? When I did richen the amount of fuel, it seemed almost as if it was flooding out when I twisted the throttle about 3/4 open. Any suggestions for the settings??

Last one: It says LOW, MED, HIGH on the face of the PCIII. Just what exactly is considered low, med, and high rpms? I generally never run higher than about 10 grand (cause, let's face it, you really don't need to on the streets), but is that considered HIGH or MED??? That would help a ton in setting things up.

Anyway, sorry it's so long, but this has been buggin me like mad lately. Unfortunately, it's either been too wet or too hot for me to do any real experimenting with the settings on it. Any comments and thoughts are appreciated ppl. THANKS!
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post #2 of 4 (permalink) Old 08-27-2002, 06:48 PM
Join Date: Apr 2000
Posts: 1,429
"Lean is mean... until it blows up"

The "low, medium, high" refers to throttle opening, NOT rpm. In carb-speak, you can be "on the main jet" while still at a fairly low rpm.

I doubt any of this helps. Personally, I'd stick with the "Devil" map until you get the bike on a dyno with an EGA and an experienced operator.
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post #3 of 4 (permalink) Old 09-01-2002, 06:58 PM
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Location: Memphis
Posts: 458
Tristan you are wrong the "low, med, high" is indicative of the rpm range not the throttle position & Rooster your tuner is right & wrong, it is much better to be a little bit on the rich side than the lean side especially with your F4i. If I told you how rich the A/F ratio was that Miguel Duhamel used for the Daytona 200 on his F4i you would come unglued & so would some people at American Honda LOL. The stoichiometric ratio for a gas burning engine is 14.7:1, while best economy will come around 15.4 & best power (which is what we want) will be around 12.6:1. Being too rich or too lean will both yield the same result in that they both lose power, but the richer a bike runs the cooler it runs as well so given the choice of the two go rich. BTW Under extreme circumstances way too rich could foul your plugs, leave deposits on your valves & even dilute your engine oil with fuel, but way too lean will burn a hole in your piston. Which sounds better to you?

Powercommander: Never adjust the settings with the buttons on the Powercommander. The adjustments made with those buttons are across a huge range of adjustment & usually hinder horsepower as they do not allow the fine tuning that the Powercommanders were designed for, basically defeating the purpose of even installing one. Those button settings cannot be retrieved from the Powercommander so you never have a real record of what changes you have made. Plus when you make a change it never sets back to zero for instance if you go up 2 lights then back down 2 lights later the PC doesn't automatically set back to where it started, it will be close but not exact so every time you make an adjustment it gets even further off. Make your adjustments within the map table itself & upload new ones each time & you can always track your progress & backtrack if needed. On the PCII each light is roughly a 4% step while on the PCIII's it is a 2% step (not exactly scientific when

My time is short & since you are not exactly a tuner that would comprehend all the details (no offense intended at all in that) I'm going to give you some quick advice. Try lots of different maps! It only takes a couple seconds to load a new map & just about any map you try will be better than stock, so experiment with it. If you find a couple maps that you like & maybe you like the low end power of one map & the top end or mid-range of another then you can copy the values from one map into another creating a new map that is the best of both of them etc...

edited for spelling

Last edited by Lord Duckhunter; 09-02-2002 at 05:27 PM.
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post #4 of 4 (permalink) Old 09-02-2002, 03:22 PM Thread Starter
Join Date: Jan 2002
Posts: 174

Thanks for all the info. I was gonna play around with it this weekend, but being that it rained damn near all weekend, I didn't get to. I guess that's the downfall livin in somewhat sunny florida.

Thanks again, bro.
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