Need help KZ550 wont rev over 5k rpm

There is no simple way to verify the igniter is 100% good unless the bike is running good all the time. That's how you know the igniter is good.

If you know the problem is for sure on certain cylinders only, then you can swap some wires and a few other things to determine if the misfire is the igniter, or coils, or pickups, or plugs, or plug wires. But if all cylinders are firing the same, and misfiring the same, then there are no easy tests for the igniter. You would then have to swap igniters with another one. (Making one is simple, by the way, if you check my signature).

Since your symptom sounds more like the advancer, I would start there. Do you have a photos of it? If there's any rust on it at all, it is suspect. They clean up really well if you can get them apart.

Would an igniter from a kz750 work? When i opened the cover for the advancer i was surprised how clean it was compared to my 750. It is still shiny and everything! the advancer wasnt corroded or stuck, but i cleaned it up anyways. I still need to get a video for you guys, someone might just know exactly what the problem is from the video. So hold tight while i try to take one and upload it.

Thanks for the help!

Yes, as long as the box looks the same on the 750 igniter, it's the same igniter as the 550. The wiring connector may be different, so you might have to run jumpers for testing. Just match up the wire colors (and thickness in the case of the black and/or red wires).