when i first got my 06 w/o mods was gettin 60 mpg..im at 4500' above the pacific ocean..since first bringin er ome in feb 06 ive done a few mods..the ones for performance /means less mpg..de snorkel,k&n drop in,turbolator,dyno jet/pilot neddle kit,3" hard krome slash cut muff,had the stealership fine tune the carb now these last two tanks am gettin a solid 50 mpg...would be better if my right wrist didnt have that forsaken snap in it...good thing i got a drivers backrest or my arms would be streached id be a...
slope headed knuckle dragen,booger eatin moron...

Well, part of the problem is, your bike is no longer set up to factory specs.

Put the white spacer back in, replace the sportster muff with the stock one and turn your A/F mixture back to factory settings (approx 1 1/2 turns out) and you'll be back close to factory performance.  It will run like crap, but you'll get closer to your goal of 60mpg.

Seriously though. There's no such thing as a free lunch.  Any changes you make to the fuel delivery system (white spacer, A/F mix) or the exhaust (sportster muff) is going to affect your fuel economy.  A richer mixture means more power, but it also means lower fuel economy.

Another culprit is the fuel blends.  Since the oil companies abandoned MTBE and other oxygenators in favor of ethanol (up to 10% by volume) you are going to see lower MPGs than you would have in the past.  The reason is that ethanol just does not pack the same amount of energy that pure gas does (79,000 btu vs. 115,000 btu).  Yes, it burns cleaner, but you're going to burn more of it.

After all, you're getting 50+mpg at a time when fuel is approaching $4.00 a gallon.  You should be celebrating, not worrying over 6 or 7 mpg more.  But if you still want that mystical 60mpg,  try raising the air pressure in your tires (slightly), take off any saddle bags or top cases (create aerodynamic drag), add a small wind screen (more of an aerodynamic benefit than anything else) and slow down.  Set your speedo at 55mph and you'll see those mpgs start climbing...

Jack_650 wrote on 04/23/08 at 23:03:46:
Second the "depends a lot in how you drive" and "mileage varies by smile factor."

I get 45-50 mpg for my normal stop hard go fast grin like an idiot riding.  On short trips that include a considerable number of stops I get 50-55 mpg.  On tour at a fairly steady 65+ I get 55-60 mpg.  Using Arizona gasoline, on California 62 at a lazy 50 mph, from Parker to Palm Springs I got a hair over 70 mpg.  California "gasoline" gives about 10% less miles per gallon than 49-state gasoline.

If you want to improve fuel economy you can lower your cruising speed.  You can also ride using the long picture -- watch the road/traffic a quarter to a half mile ahead.  Position and pace yourself to avoid braking/accelerating.  I am timing my traffic signals at least a quarter mile away -- when the choices to make the green are slow down or speed up I generally choose speed up, hence my pitiful city mileage.

Keith_T wrote on 04/24/08 at 05:54:21:


I'm using the same gas as you, I think I got 45 on mi 1st tank too, but I've been getting 59-60 ever since - the only real change I made was the dyna muff.

If you tank 10% ethanol blend gas you get 10% lower gasmileage. Gas mileage is affected by rolling resistance (keep you tirepressure up), aerodynamic resistance, inertnal resistance, head or tailwind, and especial weight. Weight has to be accelerated, pulled uphill. downhill is free to everyone. The more weight the lower the mileage. Gearing is also a factor. And of course your driving style.  At a perfect mixture of 14:1 (air to full) and i doubt that you can get this with carburation, it take a certain amount of HP and to pull you around and if weight end everything else being the same, 1.2,3,or 4 cylinders would make almost no difference. You can change all or any of these variables, but it could cost a lot and for that difference I'd rather by the extra gallon.

Matt,

Can you tell me what you had to do along with installing the DynaMuffler (rejet, etc.)? Also, how different does it sound, and does it have more power?  I was thinking of getting one of these from eBay.  Was the installation seamless?

Thanks.