dyna 2000 stutter at 4000ish rpm

[addertooth]

I installed a dyna 2000 ignition on a 2003 sportster. It has been driven about 5000 miles since the change with no problems. Recently the bike has shown a brief stutter, and always at the same rpm. It happens at 40mph in second gear which is about 4000 rpms with my gearing. Otherwise no stutter occurs. Has anyone eles experienced this? I am trying to decide if it is cam position sensor or the ignition unit. Perhaps something else I didn't think of. It doesn't happen all the time, perhaps once every 4 or 5 times I cross the 4000ish rpm boundry. Once I get past 4000 rpms it runs smooth. Addertooth

[WinXP]

Have you tried another set of plugs ? You may have one that is starting to break down. Also check the ends of plug wires at coil an plug.

[rottenralph]

What carb are you using?

[addertooth]

Plugs and wires look good, the carb is a CV40 with thunderslider kit. I may have already figured out the problem, but I will wait for a few more runs before I post what the cure was. Nobody would have guessed the fault in a million years. A "jingle" gave it away. It was that bizzare. Addertooth

[rottenralph]

I am guessing a cracked ignition pickup that was getting ready to let loose.

[addertooth]

The screw that holds the ignition switch was loose allowing it to wiggle back and forth. The sportster key was on a key ring with one other key. At 4000 rpms the jiggling keyswitch and keys would "resonate" and start slapping around. This would cause the keyswitch to briefly cut in and out. When the keys and switch were in resonance, jiggling around violently the engine would miss, due to the intermittant connection caused. The fix? tighten the @#$# screw that holds the ignition switch in place. I noticed the keys "jingled" exactly as the engine was cutting out. I took it for a morning drive, ran it past the 4000 rpm boundry several times with no missing, now that the screw was tightened. Mystery solved. Addertooth