03 sportster running rough when warm

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Apr 22, 2025 | 02:04 PM

Jordy luinge

Thread Starter

Stage I

Joined: Apr 2025

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03 sportster running rough when warm

Hi!

a few weeks ago i did a little run on my ‘03 sportster.
after i was on a little break i started it, drove away and suddenly it started to misfire. And running really rough.

the last few weeks i’ve been trying to get it to run right. But no luck yet.

When the engine is cold it runs very well. Also starts always, cold and warm.

i’ve already replaced all the manifold gaskets (don’t leak when tested)
the coil, rebuilt the carb, adjusted the pushrods and checked for the timing.

the motor is a build 1250 S&S with 200psi of compression, and a dynatek 2000i ignition.

any suggestions will be appriciated😁

Jordy

Apr 23, 2025 | 03:58 AM

Jackie Paper

Seasoned HDF Member

Joined: Mar 2010

Posts: 38,605

Likes: 6,439

From: Honah Lee

Put an clip on timing light on the spark plug wire. See if you can see if it's electrical.

Welcome to the HDFORUM.

Last edited by Jackie Paper; Apr 23, 2025 at 04:00 AM.

Apr 23, 2025 | 06:27 AM

Baird

Road Master

Joined: Jun 2013

Posts: 1,239

Likes: 1,171

From: St. Catharines, Ontario

You may be leaving the enrichener on too long and giving the plugs a fur coat.

Apr 23, 2025 | 12:33 PM

marcodarq

Grand HDF Member

Joined: May 2014

Posts: 3,843

Likes: 1,174

From: florida

what carb, what size jets, what pipe? did it run well for a time and then change or did you do the upgrade and this is what you got when done. Please give some background.
m