Gas

With the compression on my stock 88 incher, do I really need to run premium gas? I mean the compression is not even 9.0:1?

na you can run mid grade if you want

Cool, cause i am getting shiiity gas mileage. Maybe i will get better switching to migrate

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What kinda mileage you gettin??Maybe you're running a little fat(fuel wise not the rider)

Ambient temperatures and altitude will make a difference. I wrote an article on compression that discusses detonation (pinging):

Last month we discussed horsepower and torque. We want more torque! How can we do that? One of the best ways to increase torque is by increasing the compression ratio of the engine. The compression ratio is the volume of the cylinder at Bottom Dead Center (BDC) compared to the volume at Top Dead Center (TDC). The smaller combustion chamber gives you a higher compression ratio, which results in more bang for your buck, so to speak.

There is more than one way to skin this cat. You can increase compression without removing the entire top end by milling the heads and using a thinner head gasket. A change in pistons can increase compression, and machine work on the combustion chamber can reduce the size of the chamber and increase compression.

If a higher ratio is better, can it be too high? Yes. Compression that is too high will result in detonation. Detonation is bad. It occurs when the air-fuel mixture ignites on its own, causing a collision with the flame fronts of both the intended and unintended sparks. This can simply cause an annoying pinging or produce other ill effects right up to totally trashing your engine.

While the general measurement of the cylinder gives you an idea of your compression ratio, there are many variables that can affect the actual volume at any time. Ambient temperature, the timing of the intake valves, altitude and fuel octane are a few things that can affect compression and detonation in your engine. Your engine can handle higher compression in Denver, but take that same engine to Florida and you’ll be in trouble. Iron heads dissipate heat differently than aluminum heads, so the optimum amount of compression will vary between these engines. Long story short, there’s a lot to consider when making changes.

I am not sure what I am getting exactly but it is around the mid 30's to low 40's. I am so used to getting like 50-52 mpg with the Sporty.

It's not a Sporty...it's a little heavier and bulkier...low 40's is not bad for a bagger...I average around 43MPG with the king...

You can git no where what a sporty gits. You got a bagger. You are pulling more weight. And I would bet you are trying to ride the bagger like the sporty.
Try not takin off so fast, and not twistin the throttle so hard.
I got a factory 103 with a thunder-max and the best I've seen is 39.8 mpg.
But normally 36-38 if I don't run the hell out of it.
And my bike is much heavier than yours.:rant:

Like I said, the gas mileage may be where it should be, just use to the 50+. I am riding two up most of the time now. The Ol Lady likes being on the back that is for sure.

Yer OL likes being on the back. My OL has a 09 Nightster. Its shy of 1500 miles on it.
She stays on back of mine, She can look around and Day Dream
She don't have to pay attention.
As long as I'm having fun , screw the fuel milage.

Good point my friend. I like having her back there too. We are going to go on our first HOG ride together here soon. I am looking forward to that and so is she.