Jetting Sugestions

I have a freind who owns a 2003 Electraglide Classic. Stage one was done at the dealer. Problem is since carb was jetted his fuel mileage has dropped to the low 30's. Is there a rule of thumb to start with when jetting the carb.
2003 electraglide classic
Stage one breather
Kerker Mufflers
Rest is stock

HDR1, how much was the carb jetted out ? The stock jet size on a Keihin is a 190 main (it is on my ride anyway) If your friend richened the carb by having a larger jet installed, he's running way too rich ( gas mileage shows he is ) Having pipes installed will have a tendency to make your bike run rich too. Your friend, like me, will have to lean the carb out some by changing the main jet size. I dropped down to a 185 main and still experience bad gas mileage when running around 65+. It's all trial and error. Always check a new set of plugs when you're looking at how rich/lean you're running, but you have to check your main jet performance alone. And that's by warming up the bike, going somewhere where you can change a fresh set of plugs, start the bike up, ride at a good rate of speed for a couple of miles, shut the bike down and check the new plugs and see what they tell you. You have to avoid idling/low speeds as much as possible when doing this because your slow jet will affect your plug read. I'm not recommending that anyone rides like a bat outta hell down Main Street, going full out, so you can check your plugs. Being close to an Interstate is the only place to do this .... Sunday morning when the roads are not as busy. Another thing is the manufacturer of the gas you put in. Word here in Michigan is ..... do not run Mobil gas in your scoot. Your plugs will foul up before you ride 300 miles. Don't know why. Good luck.

Whaaaatt.???

WHAT ??? And all this time I've been bass-ackwards

back asswards

LMAO thanx for making my day......

Stoich...Sttroke...Air Fuel ratio

Well, heck we better throw away the theory of stoichiometric efficiency.

Let's think about this for a moment.

Let's say we have a theoretical engine that can be regulated to pumping X lbs of air per minute. We have a fuel source capable of providing an adequate amount of fuel to feed the engine as needed.

Using stoichiometric theory, we need between 13.5lbs to 14.7lbs of air for every lb of fuel this is normally expressed as the Air Fuel (AF) ratio.

This ratio provides the most complete combustion of gasoline. If you decrease the air, you have increased the fuel by default causing a rich condition. If you increase the air flow, you have decreased the fuel flow and have become lean.

Altering either the fuel volume or the air volume alters the stoichiometric efficiency correct? So, if we relate this to a normal engine you can see that by increasing the air flow (i.e. increasing lb of air per minute) will require a corresponding increase in fuel flow in order to keep within the desired AF ratio.

The simplest way to look at is that if you make your engine breathe better, you will need to add fuel to keep the mixture correct.

I have a headache now

huh

is this what you are talking about?http://www.sparknotes.com/chemistry/stoichiometry/stoichiometriccalculations/section2.rhtml

So what you are saying is if we do stuff to increase power we will lose gas milage. hmmmmmmm. I will mull that over.

Sometimes I wish I had never met Shoic...whoever.

Nope. What I am saying is that an internal combustion engine will provide the most efficiency when the AF ratio is in balance. This would hold true regardless of the volume of the air pumped through.

The difference comes in the efficiency of the capacity to pump air at a given RPM. If you produce 10hp at 500 RPM and can maintain 25 MPH using 10% throttle you will use X-lbs of air and fuel per mile right? If you increase the ability to pump air (volume) at the same RPM and you balance the AF ratio properly you increase power correct? Now, since we flow more air at any given RPM it takes less throttle to maintain that RPM.
Or, you could say it takes less throttle to do the same amount of work, reducing fuel consumption.

This all goes out the window when wristwistitis comes into play when you find all that new power.

Of course, stoichiometric is a theory and is not considered to be an absolute due to variables.

Going into a dark room now...

After many different jet trials on my 05FLHTC I learned through experience the pilot jet & needle have a much greater impact on fuel economy then the main jet. I have a stock 88 with SE A/C and hooker adjustable slip ons. Here is were I ended up after trying with the Dynojet kit and without.

Currently running stock emulsion tube with stock needle shimmed up with 2 washers from the dyno kit. One size larger on the pilot 46 and one size larger on the main 195 air bleed set at 2.5 turns out and getting about 45MPG.

With the dynojet kit installed it ran good but was fat getting about 38MPG.

My 2 cents...
Greg

I've heard of similar results for stage I rejetting. With pipes and aircleaner, I've read of many people just bumping the pilot jet up one to the 46 then shimming the needle...no need to go fatter on the main jet usually.

Definitely running lean

My 04 Wide Glide has Cycle Shack pipes and Ness Big Sucker, slow jet is a 48. Pipes are gold. I am not liking that last part.
I'm not sure what to do, should I shim the needle or put in a Sportster needle? Something else I haven't thought of?
Reading this thread pretty much confirms my suspicion that the slow jet is big enough.

BTW, for whatever reason the 48 slow jet was already in the carb, bike bought new from military sales.

Any and all input is appreciated.

Joe

Cracker, I agree for the most part. I own the exception though, my 1991 FLHS. I spend most of my riding time nearer to 65-70 (sometimes above). Granted, speed limit is 55 where I'm riding, but not many cages come up from behind that way. Thing is, with my gear ratio on final, I'm taching 3k at around 66 mph. So I'm into the main at cruising speed. If I keep the bike down to 60-62, the milage is near 40 (S&S Super E, Andrews cam, Python pipes). Up at 70, milage drops to 35. Run a tank at 80, well, at 32ish (3,900 RPM is not dead dinosaur frendly) you'd better be finding a fuel stop by 150 miles or plan on pushing soon.

Doesn't matter about the milage, the plugs look good and the bike runs great. If I want better milage, I'll take the 2004 Road Glide. The 1991 still does better than any cage I own, and the only downside to it is picking the bugs out of my teeth from smiling so much......

Air/fuel mixture

Yo Cd... I completely understood everything you said. I enjoy teaching Stoichiometry to my students. Best part of Chemistry. Peace

Man! You guys are starting to make my head hurt.

Stoichiometric theory ?

X-lbs x throttle % / rpms / mph balanced by AF ratio ( now i realize why i'am just a dumb old farm boy) this might as well by another language. (come to think of it,it is)

And all these different needle's: stock,pilot,main (I do know where the carburetor is) so i quess there is some hope.

Not good when i read a dozen posts and the one thing i understand in it is Bass-Ackwards


Now all kidding a side,(mostly) I have a stage 1 in my 95 wide glide. On Saturday, i got 54.05 MPG on a 150 mile trip. If i go to a Stage 2 How much can i expect that to drop? or as CD pointed out, if everything is tuned just right afterwards will it remain the same?

fuel mileage

Theoretically, if everything is tuned properly, it will remain the same. But typically, it will not happen. Roads, driving habits, tuning, tire inflation, mechanics all play a part in your mileage. Just like in a chemical reaction, you will never get 100% of the products produced from the reactants. This is a fact, therefore, the same should apply with gas mileage. Just read an article about How the EPA is forcing the automobile industry to change the methods in which they calculate fuel mileages. They do not give accurate mileage because their method uses a dyno and smooth starts and stops. Mileages will drop in 2007 or 2008 because of the new methods used to calculate it. Read in car and driver the other day while waiting for my wifes' doctor to show up.

Rose Guy

Dude thanks for the site. Always looking for a site to help the kids understand new material. I have a Homework page on my school's homepage that allows me to add cool Chemistry web sites. Thanks. You may have just helped a student by turning me on to this site. Peace...

Do not assume because the pipes are gold that you are running lean. Pipes will change color for various reasons. Too rich, too lean or an intake or exhaust leak...

If the bike is stock with free flowing A/C and exhaust I would start out with the stock jets (TC 88 CV 40 pilot 45 main 190) and the sporster needle followed by 2.5 turns out on the A/F mix screw and go from there. Also you need to check the rubber boot that seals the slide in the carb for tiny tears or holes and replace it if needed.

Make sure the emulsion tube is stock and be sure to check for intake leaks by spraying some carb cleaner water or WD40 at the intake when the motor is hot at idle (from the carb side of the bike). If you do it from the primary side of the bike you can get fooled because there is a chance it could get sucked in by the air cleaner into the throat of the carb.

Exhaust leaks can be found by listening with a hose around the potential leak areas, at the heads & where the pipe has joints.

Hope this helps

I like working and trouble shooting them as much as I like riding em.

Ride SAFE & keep the rubber side down...!