Rod knock?

[mrollings53]

Think I may have some rod knock. I was riding around today and didn't give it enough throttle for the gear I was in, but instead of it bogging down like normal I got a sound kind of like a large ball bearing rattling inside of a thick metal can. Almost like the ball in a can of paint, but with a deeper pitch. It lasted for four or five strikes then went away. Didn't get any indicators, or codes on the instrument display. Operated fine afterward too.

Now, I'm getting close to home, and stopping at a light when as I'm letting off the throttle to idle and I hear another noise. It is at the same speed as the regular exhaust noise, and sounds like when you blow out your mouth but keeping your lips closed, then let them flap open and closed. Like you're giving someone a raspberry. It happens for a half second, then is gone with the regular idle noise. The noise is more prevalent after the bike has been ridden for a while. It's not there at all when the bike is cold. I can also feel it while it's happening. I can't say that I've noticed it before. Hearing what I heard when I bogged it down may have made me more aware.

I took a video of it, but the sound sucks and I can't hear it in the audio. Does this sound like rod knock to you guys? Is there anything I can do to check this out short of tearing the motor apart?

Thanks for the help.

 

[alaskanflyboy]

Rod knock shouldn't disappear. What you describe sounds like detonation or pre-ignition, which I've heard sounds like metal rattling or chains dragging.

Detonation can happen from low octane fuel burning improperly, or from excessive cylinder pressures caused by overheated cylinders. Running a higher octane fuel can alleviate the former problem. The latter is only alleviated by better cooling or running the engine at lower speeds to avoid overheating the cylinders.

Pre-ignition can happen if the spark plug gap is incorrect, the ceramic insulator cracks, the spark plug is the wrong temperature, carbon deposits build up on the plug or cylinder wall, exhaust valves burn, or damage in the cylinder that isn't dissipating heat properly.

 

[mrollings53]

I always run 92 octane gas, and engine temp was between 200-212 degrees. Spark plugs were replaced at 16000 miles; the bike has 20700 miles on it now.

 

[leem00]

Rod knock shouldn't disappear. What you describe sounds like detonation or pre-ignition, which I've heard sounds like metal rattling or chains dragging.

Detonation can happen from low octane fuel burning improperly, or from excessive cylinder pressures caused by overheated cylinders. Running a higher octane fuel can alleviate the former problem. The latter is only alleviated by better cooling or running the engine at lower speeds to avoid overheating the cylinders.

Pre-ignition can happen if the spark plug gap is incorrect, the ceramic insulator cracks, the spark plug is the wrong temperature, carbon deposits build up on the plug or cylinder wall, exhaust valves burn, or damage in the cylinder that isn't dissipating heat properly.

Air injection pump maybe?

 

[alaskanflyboy]

Air injection pump maybe?

To my knowledge, there isn't one on the FZ6R. I dug through the manual to be sure and have found no mention of one.

 

[leem00]

To my knowledge, there isn't one on the FZ6R. I dug through the manual to be sure and have found no mention of one.

For the emissions on our bike...what the block off plates replace?

 

[Scott_Thomas]

AIS- Air Intake System. As leem said it's the part that you remove when putting block off plates on.

To my knowledge, there isn't one on the FZ6R. I dug through the manual to be sure and have found no mention of one.

 

[alaskanflyboy]

AIS- Air Intake System. As leem said it's the part that you remove when putting block off plates on.

There is no associated pump with that system, however. I'm assuming from the diagram that the exhaust flow itself creates a suction that draws air into the system from the air box, with reed valves to prevent back flow.

I'm not as familiar with the symptoms of that system failing as it's not found on aircraft.

 

[Scott_Thomas]

There is no associated pump with that system, however. I'm assuming from the diagram that the exhaust flow itself creates a suction that draws air into the system from the air box, with reed valves to prevent back flow.

I'm not as familiar with the symptoms of that system failing as it's not found on aircraft.

Correct, there's no pump

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[mrollings53]

Thanks for the input guys. I started it up earlier and let it idle for a few minutes. Played with the throttle some and discovered that it is exhaust noise. I put my hand infront of the tailpipe and I could feel the same series of puffs in tune with the noise.


As far as an AIR pump is concerned; wouldn't you only need one of those if the bike had a catalytic converter, and wouldn't it only be on when you first start the bike?

 

[alaskanflyboy]

Thanks for the input guys. I started it up earlier and let it idle for a few minutes. Played with the throttle some and discovered that it is exhaust noise. I put my hand infront of the tailpipe and I could feel the same series of puffs in tune with the noise.


As far as an AIR pump is concerned; wouldn't you only need one of those if the bike had a catalytic converter, and wouldn't it only be on when you first start the bike?

If you have the stock exhaust system, you have a cat. I'm not sure the parameters for the induction system running other than it's ECU controlled and is on more when the bike is still cold.

If you have a modified exhaust system, perhaps it's running a little rich and you're getting back fire.

 

[MistahT]

Thanks for the input guys. I started it up earlier and let it idle for a few minutes. Played with the throttle some and discovered that it is exhaust noise. I put my hand infront of the tailpipe and I could feel the same series of puffs in tune with the noise.


As far as an AIR pump is concerned; wouldn't you only need one of those if the bike had a catalytic converter, and wouldn't it only be on when you first start the bike?

The noise is coming from the exhaust? You could have a small piece of metal rattling around, makes sense. If it's aftermarket check the joint between pipe and muffler, you might be leaking and giving you that air puffing sound

 

[BluePill]

All USA FZ6R models sold since inception in 2009 model year have catalysts in the muffler. A broken reed assembly *could* make a buzzing noise.

From Wikipedia:

Aspirated air injection[edit]
Air injection can also be achieved by taking advantage of the negative pressure pulses in the exhaust system at engine idle. A sensitive reed valve assembly called the aspirator valve is placed in the air injection plumbing, which draws its air directly from the clean side of the air filter. During engine idle, brief but periodic negative pressure pulses in the exhaust system draw air through the aspirator valve and into the exhaust stream at the catalytic converter. This system, marketed as Pulse Air, was used by American Motors, Chrysler, and other manufacturers beginning in the 1970s. The aspirator provided advantages in cost, weight, packaging, and simplicity compared to the pump, but the aspirator functions only at idle and so admits significantly less air within a significantly narrower range of engine speeds compared to a pump. This system is still used on modern motorcycle engines, e.g. the Yamaha AIS (Air Injection System).