noise under load

Hi everyone. Does anyone have an idea about my 04 SW (22k miles) making a pretty loud "knocking" or rattling noise under load at about 3700 rpm. It only makes noise under load (uphill, riding 2 up) and I can make the noise disappear by applying significant throttle. Belt was replaced at about 16 k miles but since the mechanic left the area I cannot confirm whether it was OEM or some other product. Great forum...thanks for listening.

How much load, shock settings and tire pressure?

My guess is that you are just hearing a degree of belt slap on the slack side of the transmission. Winding on more throttle may change the variator position enough to make that resonance disappear. If you remove the belt cover you may be able to see some witness marks on the case.

16k miles is the recommended belt change anyway, so out with the spanners and in you go.
While you're in there check the rollers, pull the clutch assembly and clean that up too. All those bits and pieces are meant to slide about easily but get gummed up from dust from the belt and clutch blocks.
It sounds difficult but it isn't, just allow yourself time and follow the service manual. Otherwise find a competent mechanic but expect 2 to 4 hours labour rate plus the cost of a belt and rollers.
Of course the knocking could be something else but these bikes are tough so start with the basic maintenance stuff first.

I hate to say this, but my 04 Swing does something similar. But I've pretty much determined that it was my lockable left side glove compartment door rattling. I don't keep it locked very often so around 3500 RPM I get a nice little rattle until I get over 4000. Probably not the same problem that you're having.

Thanks for all the input. I already taped down the rattling glove box covers and front windshield garnish. As to how much "load, it seems to happen whenever I climb a hill at around 3700 rpm. I am 160 lbs, and the tire pressures are OK, so.... I will dig into the belt cover and see what I find. If I have the courage, I will go further into the drive innards.

Again, thanks! Great Forum, and I will report back.