Need Help Power Drop after 8K RPM

[vanness]

FZ6N 2008, It has a weird power loss at around 8K RPM all the way to redline (sometime power does come back for a split second), doesn’t happen if the bike’s cold, only when it’s at operating temperature, It ran fine 2 weeks ago and I didn’t replace any part during that time, no vacuum leak, injectors are working and cleaned (tested on bench with FI tester), it has new fuel pump, spark plugs are not multi grounded (NGK) as the service manual recommended, ignition coils are bench tested and in line with service spec. Currently suspecting spark plugs but because it ran fine just 2 weeks ago I feel like it’s not. Any suggestion before i order new spark plugs just to still have the same issue would be appreciated.

 

[Gary in NJ]

There are a number of reasons an engine can loose power at high rpm’s:

1. Your new fuel pump isn’t supplying the correct fuel pressure or flow rate
2. Clogged fuel screen
3. Pinched fuel line
4. Do the coils show any signs of cracking or swelling? If so it is a failed coil(s)
5. Failed spark plug wires and/or caps
6. Low compression
7. Contaminated fuel
8. Mouse nest in the air box

There are more reasons…you need to start checking obvious items. I suggest with the simple things before you start throwing new parts at the bike. Randomly swapping parts but.could keep you from finding the actual problem.

 

[vanness]

There are a number of reasons an engine can loose power at high rpm’s:

1. Your new fuel pump isn’t supplying the correct fuel pressure or flow rate
2. Clogged fuel screen
3. Pinched fuel line
4. Do the coils show any signs of cracking or swelling? If so it is a failed coil(s)
5. Failed spark plug wires and/or caps
6. Low compression
7. Contaminated fuel
8. Mouse nest in the air box

There are more reasons…you need to start checking obvious items. I suggest with the simple things before you start throwing new parts at the bike. Randomly swapping parts but.could keep you from finding the actual problem.

Update

Turns out it was the rectifier, mine doesn’t charge above 13.1 on rev, but charges to 13.8 on idle, basically the voltage drop as soon as i twist the throttle.