Bogging and Squealing Mystery

Now now before everyone starts mentioning that clutch let me describe the situation:

I built three new bikes (2 cruisers and a mountain bike) for some folks down here. I have a specific problem with the cruisers though. They turn on fine, idle great, run smooth, but there is a mystery noise I can't figure out.

This happens when I'm either starting from a slow speed or when I'm at speed while letting go of the throttle close to completely. It does not make noise when accelerating at moderate speeds. I understand unthrottling could explain the bogging but I get this hiccup type squeal from the engine. At first I thought they were defective motors but that would just be too big of a coincidence and they run fine all other areas.

I adjusted the clutch and still nothing.
Then I put some high performance grease on the gears and then again nothing.
I adjusted the carb to a high acceleration and following s nothing.

I'm running out of ideas and unless my recent thread
Title: Carb needle clip settings (can't post links?)
can explain this issue, I'm not too sure what else it could be other than a pooped motor/clutch.

Checked the clutch cover and its clearing,
Checked the wheel bearings and they perfect,

How do I go about checking the engine bearings?

My dad and I were thinking about it and thought possibly it could be because of bike and engine speeds gap. Perhaps since the engine with no throttle isn't reving high enough and the bike is going a bit faster could this be sorta forcing the trans?

Again this has proven to be quite the case

The beach cruisers are still being broken in so around 18 to 1 give or take

And yes, I realized the noise was slightly present on my commuter when letting go the throttle too.

Cabinfever1977 said:

what gas and oil ratio are you using?
and when you let off the gas at higher speeds it will bog down and made a noise like if youre driving a manual car in 1st gear.

Click to expand...

So does it mean the noise is strictly from that effect?

If so, why is it so much louder and profound on the cruisers?
I'm guessing because they're new?

I think if it were the clutch rubbing it's be apparent more often.

Although the whining down you described is a perfect depiction of what my problem entails.

Hope we can find either a solution or if its just these engines that do that.

Pulling the clutch works like a charm takes away the noise and all, so I'm guessing its just the engine rev and bike speed matching that causes this noise.

Well I guess as they get broken in it will dull out like on my commuter bike. Thanks for everything!