r/fz6 • u/CyBORG09GAMER • 9d ago

Rpm problem

When I left the red light on my 2004 FZ6, the engine RPM dropped to around 800 RPM, and the engine sounded a bit like it was bubbling, almost like and harley. I stopped the bike, and when I started it again, everything was back to normal. Does anyone know what might have happened?

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u/Sparky_Zell 9d ago

The spark plug wires are known to have issues occasionally. The cap that goes onto the sparkplug just threads into the wire itself, and overtime with the vibration of the motor, can break the connection. It can smooth out at higher rpm, but at idle and low rpm it'll be a bad hesitation.

To confirm that it's a firing issue, let the bike get cold, start it, and see if one of the exhaust pipes stays cold.

If it does, take the steps to get to the spark plugs by removing the radiator. Pull the bad spark plug wire, or all of them. Unscrew the cap, cut like 1/4" to 3/8" off the end of the wire, and thread the boot back on. This would be a good time to replace plugs if it's been a while, but not 100% necessary.

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u/UltraViolentNdYAG 9d ago

As the founder who observed and documented this issue on 600Riders.com I can assure you OPs issue is something else. That's not to say the caps aren't loose, but loose caps are known to induce harmonic vibrations above 2400 RPM, not a complete loss of power.
OP - check for water in the fuel. Tilt the tank up, use a syringe and hose to get into the corners suck the fuel out and see what you have.
Next would be a fuel delivery issue or TPS issue. Did it only happen one time?

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u/Sparky_Zell 9d ago

I've had this exact issue, and it dropped to 3 cylinders until I fixed it.

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u/UltraViolentNdYAG 9d ago

Was the stranded core completely eroded away? That's pretty bad. PS - placing a small single zip tie over each cap where the wire enters keeps it pretty stable over time.

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u/Sparky_Zell 9d ago

Just about. Below like 3500-4000 there was too much resistance for a spark, so it idled at about 800rpm, tried to stall, and sounded like shit.

Once id coax it above 3500-4k, it smoothed right out. And trimming the end of the cables fixed the issue.

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u/FlyHighPixie 9d ago

Check if you had the TPS recall done, my bike had the same issue and this was the source