Topic: New Starter Motor - weird noise 1974 CB750

[JonathanHValencia]

Can someone tell me what this is?
I installed a new starter motor and a new kill switch. I tested it just now for the first time just to ensure the motor was good and I got this noise. No carbs currently installed, and my timing is way off. I only did this to test the motor would receive power and I’d hear the classic noise.

Help please
Here is a video

[ekpent]

 I looked at parts of your long vid quickly but you really need to give us a minute/second mark in the 9 + minute video where you think you hear something sounds weird..

[JonathanHValencia]

The very end just after I hit the ignition switch

[JonathanHValencia]

Rewatch the video. I posted the wrong one initially. Sorry

[goldarrow]

Is Your new starter motor, brand new brand new? Or is is new to you? 

[JonathanHValencia]

New to me.

[goldarrow]

New to me.

I’d say start off with disassemble and clean everything inside the starter motor and go from there

[JonathanHValencia]

I only tapped the ignition button to elicit a response from the starter motor, not with the intention of turning on the bike. Literally just tapped it for 1/4 of a second

I won’t try turning it over until I have the carbs in and the gas tank hooked up.

[Yamahawk]

I noticed that you have what appears to be latex gloves rubber banded over your intake boots... did you happen to notice them sucking in when you tried your starter? It sounds to me like the gloves are being sucked into the engine by the intake stroke...
Charlie

[JonathanHValencia]

I didn’t pay attention to that. Yeah since I have the carbs off I covered the intake with gloves lol I figured just tapping the button wouldn’t be enough to trigger an intake response, just enough to send a jolt to the starter motor which I wanted to hear. But my theory is probably incorrect

[Yamahawk]

Yep, every time the pistons lower in the bore, it creates suction through the intakes... at least the ones on the intake stroke. Pretty sure I heard latex creaking after the suction was releasing slowly. Also, for a fraction off a video second, I saw the glove looking like it was sucking into #1 cylinder. Not a good thing to do cranking the engine with anything stuffed into the intake boots. A rag, or paper towel could be sucked into the cylinder area or get stuck on a valve easily.
Charlie

[Stev-o]

Rewatch the video. I posted the wrong one initially. Sorry

Thats what I thought

[pjlogue]

Take the Nitrile gloves off the intakes!   You don't want one of them getting sucked into the engine.  You will also find the noise is from the gloves.  LOL.

-P.