Probably just needed a downshift to get the rpms up. They'll rattle like that if you lug the engine.

Your top or bottom motor mounts are possibly loose, the top's location is obvious, but be sure to tighten the 3 holes in the bracket mounts on both ends at the top (3 bolts).   Hold on one end while tightening the other end at each of the 3 places up under the gas tank.

The bottom two mounting points are more devious, the front is a LOOOONNNG bolt that goes through both of the peg mounts on either side.    Hold on one end while tightening the other end.  Bottom back mount is closer to the pivot point for the swing arm (while you are back there clean then tighten the - negative -  electrical ground point since you are in the neighborhood).

You can't go further looking for your sound without making sure the engine mounts are nice and firm.

After that, start laying your hand on the speedo when you go to "tinny ricky" noising and see if it stops.

After that, start laying your hand on the headlight when you go to "tinny ricky" noising and see if it stops.

Good luck, there are just so so many places that can make a noise that you have to actively remove the known "easy causes" before you get into your serious hunting.

I'll crawl around it tomorrow and check into that. But it seem inherent to the rpms under a ton of demand...ie from highway speeds to wot, it just sounds like slapping metal... Almost like pre ignition...but it runs fine other wise no noise until wot on demand...you can work up slowly to wot no issues...can the throttle be so wide open that it would go lean and pre ignites?

I had an Oxygen sensor on my bike when I jetted my carb.  And yes, when you first "crack" the throttle open the engine can go lean when you have a roundslide carb - but the CV carb is not supposed to do that.  On the roundslide carb when you crack the throttle open fast.....the velocity of the air in the venturi suddenly drops, and it does not pull from the jets as well as it did before you cracked the throttle.  In a second or two the velocity stabilizes and the mixture goes back to normal if the bike is jetted correctly.  When you crack the throttle open fast on a CV carb you are opening a butterfly, and the slide that is vacuum controlled is supposed to react by dropping and keeping the vacuum constant....and it will then raise and allow more air flow as the engine speed increases.

If you open the throttle fast and the rattling is heard.....but not heard if you roll on the throttle a bit slower but still are going to full throttle....then maybe it is a lean condition caused by opening the throttle too quickly.  

It might be pre-ignition.  Try a better grade of gas on your next fill up.

Jsud04 wrote on 06/01/14 at 18:37:09:


Woo Hoo!  My lucky day.

When I had the O2 sensor and meter on my bike to help with the jetting, I really learned a lot about how the mixture moves around with throttle settings.

You might try going up one main jet size and see it that helps.

Dave

What kind of air cleaner and muffler do you have?  Have you ever had the carb apart, changed jets, or done a white spacer mod?