I am gathering information to prepare for some upgrades to my bike. I think I have decided to do the S&S 107 Big Bore Kit for my 2008 Street Glide with a 96" stock engine with a Stage 1 done. I plan to use moderate cams and aim for lower rpm torque more than crazy upper rpm horsepower.

My question is for those who have put in big bore kits: How much of a hit am I going to take to my gas mileage. Right now I am getting around 36-38 mpg running down the interstate at 75.

 

if I keep my cruise on and my hand off the throttle I can get 36-40 with my S&S 124.....I can't see how you would lose MPG

 

when i had my 2010 96'', i took it to fuelmoto and had their 107 kit done. before, my mpg was right around 40mpg combined city/hwy. afterwards, i got 42mpg combined. mostly. there were times that i would get less, if i rode a little more 'spirited'. but in normal, average riding, i actually got better.

 

Should stay in the 34 to 38 range if it's tuned right, I average 35 on my stock 107" M8 but I do a load of in town riding.

 

Gas mileage? Whats that??

 

Your tune is probably a larger contributor to your fuel economy than the big bore would be at a 107".

I run a 126" FM Outlaw engine - If I behave, my MPGs are pretty close to stock. I'm still able to get 210-225 miles from a tank of fuel.

However, if I get a little over-zealous with the throttle, they will of course dip. Nothing drastic though. I think you will be just fine.

 

ive a 107 with a stage 4....... havent noticed much of a mpg difference.... im taking it out on tour next week so ill see if it has been affected doubt it....... increased HP usually translates to less energy to get going

 

wow, ok...I recently bought a 2009 ultra classic that was originally a 96ci. Was upgraded to a 103ci, 510g cams, SE slip ons, SE pro tuner. Now IDK what mileage it used to get but I barely get 30-32mpg. It has power all day long but the most Ive gotten out of a tank is 187 miles

 

 

had the S&S 106 kit on my old bike. Mileage stayed the same....whatever it was. I was too busy mashing the throttle to care.