1996 with Jardine pipe - no carb mods - stock filter 7K miles - 87Oct. no ethanol - 400lbs rider 50mpg regularly - never over 50mph - no highways etc - just to & from owrk 45-50 zones

surely this is odd, but the 4speed is slightly higher geared.  I don't think it's enough for 8% better gas mileage.  that would be better explained by one less gear shift.  And with the 5speed came leaner jets.  So lean that when I went from a stock 145 to a 150, i got better gas mileage.  So if anything it wasn't zuki's fault, blame the epa.

To answer james may: Quoting Widipedia 'Royal Enfield is now the oldest motorcycle brand in the world still in production with the Bullet model enjoying the longest motorcycle production run of all time'. First in England, of course, and now in India.

The 500cc Bullet thumper has about the same horsepower/torque and weight of the Savage/S40. It's been modernized to fuel-injection (claiming 85MPG), electronic ignition, front disc brake, and a unit construction engine. Two-year unlimited miles warranty. See http://www.enfieldmotorcycles.com/models/classic-g5.html

It's chain driven and much more handsome than the Savage/S40 if you prefer standards to cruisers, as I do. A cafe racer, trials, and continental kit are offered. I'm thinking of getting one. Cheaper than a Savage-based Ryca conversion. See http://www.rycamotors.com/

I get between 35 and 40. jardine pipe with the baffles blown out, cone air filter, 155 main jet, don't recall the pilot, stock white spacer.

no clue why i get such poor gas mileage. i mean, i do get on it and live in a hilly area, but there i haven't figured out why i'm getting this low...

This is the fuelly page for my '06 S40: http://www.fuelly.com/driver/sjaskow/savage-ls650.  It's got mileage back to the first time I put gas in it in August of 2007.  The bike is 100% stock with the exception of a Suzuki wind screen.

If you don't want to read the data, I get between 58-60 mpg on my normal commute loop which is about 85% surface streets and 15% interstate, i.e. 70 mph+.

I can get mid 60's if I keep off the interstate and keep the speeds down to 55 or less.

Whenever I ride a trip with speeds between 45-55 and try to be relaxed on the throttle I can get up to 63mpg, like last weekend when we did the Talimena Scenic Drive at night. Whenever I fix something on the bike and the make a test run, usually on Hwy 69 North for about 15 miles and turn around and go back, which is usually done at full throttle most of the time with keeping it around 85-90+ then it starts drinking and can drop to as low as 40mpg. Usually we have south winds and then it redlines at around 95. On the way back you can feel the head wind and it struggles to go above 85. On a tour on the open Highway with maintaining 70-75 it does around 50-55 mpg. Then I try to give just enough throttle to stay at that speed. Throttle position is a big factor on my bike.

Which prompts my next question, what grade to you fill with? I use the cheap 87, does a higher grade help with the backfiring?