I am using good, fresh coffee (roasted less than a week ago).
I am NOT using a pressurized portafilter or basket
I am leaving the machine on for at least 15 minutes to make sure it gets nice and hot.
I am dosing about 17 grams, leaving a bit of head room. My machine automatically pre-infuses the shot for 3 seconds before pulling.
I am getting good crema if sometimes a bit blonder than I would like.

My top third of my shots are quite frankly kind of unpleasant, drinkable, but alternating between bitter and sour.
The bottom half of my shots however, are wonderful! I can taste the distinct flavors of the bean, the taste is balanced, and it leaves my mouth feeling quite happy for about 20 minutes after. I just wish I could get that taste from the beginning.

Any suggestions?

Welcome to HB!

Pull shorter.

Stir first.

This is normal.

If the above does not work, replace grinder.

- Mike

+1 on stirring.

You might also experiment with dumping the first and last part of the shot.

Take a look at this /espresso-g ... tions.html especially the section on the rule of thirds.

Good luck!

mivanitsky wrote: Stir first.

By stir first, are you referring to the Weiss Distribution Technique or do you mean before drinking the shot after it is pulled?

Improve your Espresso with Weiss Distribution Technique

Thanks,

-Dom

EDIT: I just decided to try stirring it right before drinking. It made all the difference! Such a simple solution, why didn't I think of that sooner?

After it is pulled. If part of the shot is excellent, chances are, you are already doing your basket prep adequately.

There are threads here from years ago, where the extraction is fractionated by time and differences from beginning to end of shot are well documented. Perhaps those involved could provide a link. The last part of the shot, especially if blonding is present, tends to be unpleasant in isolation, but usually adds to the balance of a well-extracted shot as a whole.

-Mike

I'll browse around the site and see if I can find it somewhere.

The stirring certainly did the trick for me.

Thanks!

dominico wrote:I'll browse around the site and see if I can find it somewhere.

/espresso-g ... tions.html

It is also referenced in some of the newbie videos and some other posts, such as Pressure profiling, flow profiling, and a new rule of thirds