2016 RGU. Stock condition. 18K miles.
Lately I have been noticing a short kinda howl sound near the clutch area when engaging first or second gear.
The sound is not there when sitting still with the clutch disengaged (clutch handle pulled in) and in gear.
The sound is not there when sitting still in neutral with clutch handle released.
When sitting in neutral I can shift it into 1st and no howl sound until I release the clutch and begin rolling.
Happens under normal to hard acceleration.
Sound does not occur when in slow traffic and working the clutch in any gear.
Kinda sounds like it might be a dry bearing surface.
No oil leaks at all.
All oil levels are correct.
No slip in the clutch performance.
Belt is adjusted properly with tensioner tool.
I haven't pulled the primary cover off but inspected clutch through derby cover. Nothing obvious.
No metal in primary, tranny or engine oil.
Any idea what it might be?

 

Would a whirling sound be more appropriate for the noise you've heard? Could it be air moving into the throttle body? Have you made any modifications at all to your bike? Even adding an air vent?

 

The sound is definitely coming from the clutch area. Maybe a whirling sound could describe it.
Stock condition.

 

My bike has done the same thing, exactly as you've described. I've pulled my inner primary completely off, disassembled my clutch and my compensator, pulled my inner housing, everything checked out. Check the bearings in the front wheel, rear wheel and sprocket, they're all good.

My bike has over 38,000 miles, 2015 Limited, ventilator A/C. Just changed my inner cam bearings, lifters and both cam chain tensioners, and breathers. I've sent in oil from all three holes to be analyzed, everything came back fine.

I really hate to pull the transmission but since this howling / whirling noise is only happening in 1st and 2nd gears, I'm wondering if the bearings in the transmission door are the culprits. I'll be watching this post to see what else is mentioned.

 

This symptom seems similar to mine, 2016 Ultra Classic. I think it is the drive belt. Mine has done this since the bike was new. Now 24k miles. It isn't getting worse. My belt looks fine to me, and it is carefully tensioned to be at the large end of the deflection range at the tight point of the belt at ambient temp, exactly as the manual specifies.

I think the lowers and the faring reflect the sound back and make it seem louder. I only hear it during gentle take off with little clutch slipping. If I slip clutch a little more and get going a little harder I don't hear it. I run stock pipes. I doubt I would hear this over loud pipes. Yes definitely coming from left side, belt side. Just a short whirr. No vibration. I think this is the drive belt trying to be a guitar string.

 

The sound does not seem to increase in tempo as the bike accelerates as you would expect if it was an issue with the wheel bearings, brake rotor or rear pulley. I'm wondering if the sound is still there in the upper gears but just being covered up by wind and motor noise.
It doesn't happen when slowing down or engine breaking.