I replaced my voltage regulator. The bike starts hard and runs poorly, like it's missing. The check engine light comes on after a couple of seconds.

 

Couple of questions.
What bike are you talking about and what kind of mods does it have?
Why did you replace the regulator? Was it diagnosed as no good?
If the CE light comes on there's a fault code. Pull up the code.

 

It's a 2003 Dyna fxd. Voltage regulator was shot.

Bike has no mods except for the coil. Ran great until the V.R. went. How do I pull up the codes?

 

Here try this;
http://lmgtfy.com/?q=pulling+codes+on+2003+dyna
YOU get to do YOUR research, it's fun and informative.

And you usually only need to post a question once,, then try to wait a little while,,

 

All Right. So I went to Youtube and saw the video, followed the instructions.
On my odometer it comes up: do1clr. After I push the reset it comes up: do2clr. This happens through to the # 10. The it comes up PPU. Then back to 1 again.

 

Videos and pictures are cool and they do help, but sometimes is good to
"read" some of the other links.
(if you can)
Did they have something like the "No Child Left Behind Act" in Canada too?

 

There's usually a reason that the voltage regulator goes out... and it's usually not the voltage regulator... it's either upstream (alternator) or downstream (battery/connections).
Regulator going out to me means you have not found the root cause yet.

My alternator went out, took out my voltage regulator and my battery.. course, battery was 7hrs old and needed replacing anyway... but, non the less... it finished it.