Hmmmm, let me just say that my 4.88's, even with a stock tune make pulling my trailer pretty much effortless. Hills are of no concern for me. My gross weight is 24k.
If all you are doing is 55 mph the rpm is 2000 in OD exactly with 19.5 tires.
60 will give you 2250 rpm and 70 is 2500. You could imagine the stump pulling power if you shifted down. Even getting on the Interstate is no problem, just floor it and you're right up to speed.
If I keep it at 65 I get 9+ mpg hills or flat country. If I load the Tow/Haul tune I get 8 and too high of EGT's so I keep it stock anymore. You might do better with a smaller frontal area.
So I am going to recommend that you get at least the 4.10 and I think for what you use the truck for you would be even happier with a 4.30 or 4.56. 4.88 is a bit low geared and am saving for a US gear OD unit.

 

Dan, I guess I am premature here as I am still trying to fathom your post. I will say that sub 10mpg #s are unacceptable to me no matter what. I would have to relook what I am doing. Not saying that is bad, just saying that ain't for me.

Maybe Earnest's wing and those gears bear some looking. I know I was looking at gears for my truck and I hardly tow much, just for the highway. Fortunately I don't log many miles but a trip to New England may be looming here soon.

 

Cody, have you checked or scanned to see what your ICP is running at peak pressure? Reason I ask, I'm thinking low ICP could lead to pooly atomized fuel, which obviously doesn't burn as well, and can give excessive black smoke?

 

Nope, haven't checked that. It's a great thought. However, with the tunes on my truck, how am I supposed to know what I should be seeing? Are you suspecting a crappy sensor that is incapable of reading the elevated pressure? Or possible a HPOP issue? Thanks! I was always under the impression that low HPOP pressure caused lean(er) issues....like not enough fuel.

 

Maybe I'll pirate the sensor out of my brother's truck for the weekend. But his has 180K on it.....maybe not.

 

Jody's tunes should give you around 2600-2800 psi of HPOP pressure. I'm not thinking a bad sensor, they don't fail often. I'm thinking more along the lines of a weak HPOP. Not weak enough to set a code, but weak enough to not fully atomoze the fuel.

You're right that low HPOP pressures can cause less fuel, but they have to get really low to stop providing fuel. At that point, you would see a code thrown by the computer for low HPOP pressure. These injectors have a 7:1 multiplier ratio. So, if you're running 2800 psi of ICP, your fuel will be injected in at roughly 20,000 psi. But, if the ICP is down around 2200 psi, fuel's only being pressurized to 15,000 psi. At 15,000 psi, there will still be plenty of fuel, just not properly atomized. IIRC it won't throw a code until pressures drop to 1600-1800 psi seen at the ICP.

FWIW, using AE to scan my ICP, I see a peak of about 3000 psi before it quickly levels off to about 2850 psi. That's with Jody's tunes. Of course, I also have dual HPOP's too.

 

Well, looks like I'm going to work tomorrow before I drive to the mother in law's house to load a few tons of hay and I'm grabbing the scanner. The whole "working at a dealership" thing DOES have its upsides".

Thank you so much for the info Jeremy.

BTW, I have been riding the snot out of my ZX-12 lately. Got a free PC III USB and LCD display and free dyno tuning (friends in high places). Been a little warm lately to ride...High 90's and 106 today. UGH. You riding much lately? I had plans to go to the Keith Code school.....one of these years.

EDIT:
Rep given.

 

Nice score on the PCIII. You simply can't beat some custom tuning. It's amazing the difference in rideablility and power with a custom map versus an off the shelf map. I had my old '03 R6 race bike custom tuned, and it made a big difference in how smooth the power came on in addition to a 5 HP increase over the previous map. The map I had loaded before tuning was even for that bike with the Ti-Force full system I had on it!

Riding lately...not in the past couple of weeks. Michelin just recalled a bunch of Pilot Power's and Pilot Power 2CT fronts. Only the 120/70 fronts and a couple DOT numbers were affected, they also have to have been made in France. Well, the new 2CT front I just put on the Gix ('07 GSX-R 1000, BTW) is one of the recalled ones. Michelin said there is the possibility of a high speed tread seperation. Since I have to hit highway to even leave the house, I wasn't taking the chance. That really sucks, expecially since I took off new stock rubber to put the Michelins on, and already sold the stock buns.

Michelin doesn't have a ETA on when the new tires will be ready, so the bike has been parked for the last couple of weeks. But, I did have one of my racing friends give me a Michelin PRC (Michelin's DOT race tire) front that she - yes, she - is done with. I moutned and balanced it earlier this evening, so I can at least ride again until the replacement 2CT gets here. The PRC has some good life left in it, but I'm not big on running race take-offs on the street. I know they can get harder after a few heat cycles, and lose some of their grip. I've experienced that plenty during pre-race practice when I was running the previous weekend's tires that had been raced on. It's controllable on the track, but not exactly safe on the street.

I just realized this thread has gone in about 4 different directions. We really have a way of getting off track around here. Oh well.

 

Jeremy you beat me to it. . . something about getting home at midnight But I definitely agree that low pump pressures could cause smoke and not a lot of power. High pressures and still smoke all turboed up means you have more fuel then your turbo can mix with, which I don't think is your case. So its gotta be a pressure issue. I think if anybody knows about low ICP. . . its ME at 1300 PSI as WOT!!!! I'm getting passes by shopping carts!
Tim

 

I agree fully. I thought that my bike ran really well and there wasn't any improving it. Boy was I wrong. Running that thing on the dyno revealed that Kawasaki couldn't write a fuel map to save their lives. I now have a map for 13.5:1 across the board and the response and power delivery is AWESOME. It's hard to believe that a map for one bike (my friend's that this came off of) and my bike can require such drastically different tunes to run right. I have the stock exhaust headers with a Two Brothers can and he has a full Akro titanium/carbon fiber system. Our maps were completely different. I rode mine with his map loaded.....HA HA. Talk about dead spots!! I took fuel where he subtracted and vice versa. I still think mine runs a lot better!!

I can't wait until Dynojet comes out with a LCD display-programmable timing box and the firmware to run it. Right now I'm stuck at 8,5, and 3 degrees advance (what my friend loaded at Dynojet) and I'd like to play with it some more. Oh, and 158.7 HP at 10,200. YEE HAW!!

 

Considering the size, weight, 4x4, 4.88 gears, rather large frontal area, etc, I'm not surprised at the mileage figures. I could do a lot better but it would require staying below 60 mph. It takes a LOT less effort to roll the rig through the atmosphere at 55-60 than to maintain 10 mph faster.
Next aquisition is a US Gear OD box, saving for it right now. It's 3x faster to save up for it beforehand than to pay it off via a credit card afterward and I don't have to pay all that interest to the bank.

 

Tires are too darn expensive. I run my race scrubs ('04 GSXR6) on my street bike ('04 CBR1) and they last a good long time. Gotz ta love Pirelli!!!

blame the EPA for that.

Not really. You have a different header on another bike. Many Many variables go into the way a bike runs that most people never realize.