Primary Chain rattle

[kdurfee]

I've read a lot about this already. I have adjusted my valves before, and synced my carbs, and achieved a beautiful quite idle at 800 RPM.

Now - spark plugs are good, carbs are synced, valves are adjusted, stator bolt is tight.

Last fall I was trying to beat a yellow light that once it is red doesn't like to turn green for my bike. I had the engine revved pretty high. The idle was perfectly quiet before that incident, but afterward it was noisy.

Any ideas?

Thanks.

[Rambozo]

I would check carb sync first before taking anything apart. Are you using gauges or carb stix?

[kdurfee]

I just carb synced it two days ago. I use dials, and I made sure that each of the four dials gave the same reading for an individual cylinder, so as to make sure all of the gages were synced. I also checked the spark, and they all look equal in intensity. I have accell coils. The spark is strong.

[Rambozo]

Have you done a power balance test?

[crazzy450z]

Have you done a power balance test?

Please describe this test?

[biguns]

What I think he is saying is to test how much each cylinder contributes by watching the tach or preferably one you hook up and digital indicator is better , unplug each cylinder and check the RPM drop, the one that doesn't drop down RPM`s as much is suspect because it is contributing less.
BTW, when you posted primary chain rattle I first thought of carb sync because these chains are beefy but will knock around when idle is inconstant, usually it is carb sync but a dead or weak cylinder can cause it too.

[Rambozo]

That's it exactly, for all the reasons mentioned.

[crazzy450z]

Got it.. Thank you for the description. I had the feeling this is what he meant, but wanted to be sure.
I get some rattle, especially if I don't slip the clutch correctly taking off.. I have checked both the valve clearances and carb sync.

What I think he is saying is to test how much each cylinder contributes by watching the tach or preferably one you hook up and digital indicator is better , unplug each cylinder and check the RPM drop, the one that doesn't drop down RPM`s as much is suspect because it is contributing less.
BTW, when you posted primary chain rattle I first thought of carb sync because these chains are beefy but will knock around when idle is inconstant, usually it is carb sync but a dead or weak cylinder can cause it too.

[biguns]

If you have a good ear(or a really bad cylinder) you don't even need to watch RPM you can hear/feel it.