I know, you are wondering why this is here. I couldn't figure out where else to post it.

I had a problem with my bike being hard to start when warm or hot. So compression releases installed. Starting problem cured.

Prior to the install my low fuel would come on at 147 miles and I'd run to 165 miles or so and tank up with usually about 4.2 gallons. About 39 mpg.

Now with the compression releases I get low fuel indicator at 133 miles, run to 150 and fill up with 4.5 gallons. About 33 mpg.

This happened immediately.

So a 15%+ reduction in gas milage. I thought 39mpg sucked but 33mpg really bites.

2007 Ultra
103 SE stage II kit
Mufflers that came with the kit
V&H true Duals
No aftermarket FM system.

 

Just reading this gets me quite confused. Someone correct me if I am wrong, The 103 flat top piston and a stock head makes something like 10:1 compression. Add the 255 cam, I can only imagine what the cylinder pressure is. So compression releases were needed to start with. Now to the added confusion is how in the he!! could just installing the releases cause a drop in mileage.
What procedure was used in installing the releases?
And if we do find a problem with the releases or install, I think this is a prim candidate for a SERT or Tmax and a set of Woods TW 6-6 or similar grind cam. And $200-$400 worth of head work would have made some real #s JMO

 

Hell, I'm confused. I wouldn't think the compression is that high but what do I know?

Dealership. They used the Screamin' Eagle® Mechanical Compression Release Machining Fixture to drill the heads and install.

 

There is no way the compression releases would have any effect on your MPG.........no way at all.

Steve

 

Ya, I don't see any way that could possibly affect your MPG, no way. There has got to be something else going on. I know you said it happened instantly, I've had things happen like that & it's always something else! Hope you figure it out

 

The only way the CRs could have anything to do with it would be if one or both of them were sticking open.....but I should hope you're not so hard of hearing that you wouldn't notice!

Yep, you've got other problems. I think your MPG kinda sucked even before, FWIW.

 

S/E flat-tops in a stock'ish 103 is not gonna be anywhere clsoe to 10:1 ~ espically on an 07 with less than zero deck height. 9 ~ 9.2 maybe.

As far as the mileage goes.... you need to look into the tune. Running too rich can be as bad as (sometimes worse) running too lean. Excess fuel will wash the lubrication from your cylinder walls and if/when it makes its way past the the rings, it will begin to contaminate your oil. Pull you oil dipstick and see if it smells like fuel.... I have a sneaking suspecion it will.

 

Phil, gotta dissagree with you on the compression, a 103 with SE pistons, assuming 7 thousands down which is what I have seen, cc'd several sets of 06-07 heads at 85cc this will put you at 9.8 to 1 even with the HD gasket, use a cometic 30 and you are basically right at 10 to 1 As for the impossibility of installing comp releases not affecting mileage, I can think of two scenarios, they didn't pull the heads and contaminated the cylinders when drilling causing loss of compression and efficiency, or, they removed the heads and now have a leaking intake gasket after re-assemly. Could also be a leaking exhaust headpipe giving the 02 sensors false readings.

 

Bob, I gave a short thought about someone cutting the holes with the heads on but then I figured who would be that stupid.

 

About 90% of the HD dealer service techs. Got to remember Flat Rate, get'er done quick so I can make some more money, move that iron.