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Gas mileage question

SavageShy

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(2000 sportster 1200c) Ok guys, ive done a complete tune up, new plugs, taylor 11mm wires, and a carb clean. Ive got se slipons and a hammer air cleaner and i i finally got a chance to get real mpg numbers (no carb drain and removal) and im sitting at 30 mpg!! Now, ive known the bike is a bit rich with stock jetting, probably due to altitude, and its still ~35-40° here, so i let it warm up for quite a while, and ride with the choke on for a substantial amount of time each ride, and with the accelerator pump im losing a squirt of gas every time i blip to downshift, and im pretty heavy on the throttle when accelerating, but 30 mpg still doesnt seem right. So the question is, is this normal for winter driving conditions like ive described? Or is something seriously off here?
Secondly, i dropped down to a 165 main right after my fill up, and the bike is definitely closer, but it still hesitates in mid rpms when i give it throttle so im wondering if thats just normal for these cv carbs, or if thats thats a sign of it still being too rich at this point? The local Harley guy says its fairly normal, but i i a perfectionist when it comes to these things and want to be sure.

So do I need a driver mod, or just more tuning? Or both?
 
Accurate gas mileage requires either several tanks or sustained highway driving. My '07 Electra Glide always got 40-42 mpg. I put new cams in it and did a lot of around town riding for a while. Two tanks resulted in 28-32 mpg. I was concerned, but had a overnight trip planned, so did nothing. The 600 mile trip resulted in my mileage going back to 40-42 mpg. Wrist action has a LOT to do with it. You should not have to ride with the enrichener/choke out for more than a short time. I think that carb needs to come apart for a proper overhaul and all intake gaskets checked also.
 
So i think what youre saying is i shouldnt freak out over 30 mpg? I know my wrist is working against me at all times. As far as a complete carb overhaul, all gaskets and whatnot look good, but it certainly wouldnt hurt, if nothing else it would probably be good to get a fresh needle in there. Ill try less choke, and *attempt* to temper the wrist action and post back. Should be good riding weather this weekend :)

I kind of just expected to be getting at least 40 in town
 
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Hesitation in "mid rpms" could indicate, to me anyway, a needle adjustment. The needle will have more effect on mileage than anything else except the wrist.

Best way to get an accurate read on mileage is to find a 50 mile stretch of highway with as little change in elevation as possible. Fill the tank and run the 50 miles out and back holding throttle at a steady 60-65rpms. At 100 miles, fill the tank and do the math.

Remember that the MoCo gets mileage ratings under laboratory conditions which we will never replicate so the MoCo mileage ratings are pretty useless.;)
 
Thats kind of what i was wondering. Idle mixture seems ok, part throttle is actually pretty good for not having drilled out and adjusted the screw yet (i know, i know, laziness) and WOT high rpm seems ok. So that leaves a needle issue. Hopefully its just that it has 28k miles on it, and a stock replacement will work. I wont even pretend to know anything about needle taper and diameters
 
UPDATE: I've come to the conclusion that the CV carb is not the best. Compared to all my other bikes this sportys carburetion has been pretty poor despite constant tweaking. Add to that 30k and 20 years worth of wear and tear, I realized that by the time I rebuild, tune, and otherwise "fix" the stock carb. I would only be a little bit ahead of a Mikuni costwise. So I ordered an easy kit, got it for $275 shipped. I will report back once it is installed, if nothing else in case my findings are useful to someone else. Now I do realize i could just have a simple air leak, or any number of easy fixes, but that is exactly why I think it will be easiest to start fresh with everything and eliminate all unknowns. Not to mention the extra riding time ;)
 
Wrong conclusion; the CV is every bit as good as the Mikuni and easier to tune. If interested, I will search my archives to find a test comparing the two and they are so close from a performance standpoint that one could call the test a draw.
The Mikuni is a good carburetor, not dissing the hardware. The main difference between the two is the CV is vacuum operated and the Mik is cable operated. The cable operated Mikuni does not have the milli second lag that the CV does to move the slide so what some perceive is better performance is simply a little quicker throttle response which does not translate to more power.

If you can't be the CV rignt, it's not the carb.;)
 
I have the mikuni on my 2 big twins as the suffered a lot from carb icing with the CV however 883 sportster ran well on the CV with no hint of carb icing
Carb icing has more to do with the amount of moisture in the air and can occur between 3 and 15 degreese centigrade below 3 the airborn moisture is already frozen
Big bikes run much better with a mikuni in my environment

Brian
 
I have the mikuni on my 2 big twins as the suffered a lot from carb icing with the CV however 883 sportster ran well on the CV with no hint of carb icing
Carb icing has more to do with the amount of moisture in the air and can occur between 3 and 15 degreese centigrade below 3 the airborn moisture is already frozen
Big bikes run much better with a mikuni in my environment

Brian


Moisture in the air...surely that isn't a problem for you Brian? :D
 
Not at this time of year as hardly gets warm enough to turn to moisture although just warm enough today and humidity down low at 76%

Brian
 
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